0001193125-26-104547 | 10-K | XBRL Viewer

Adjustments to reconcile net loss to net cash used in operating activities:

$ (164,076)

$ (118,961)

Non-cash royalty revenue related to the sales of future royalties

(54,932)

(64,267)

$ (591,365)

Non-cash interest expense on liabilities related to sales of future royalties

26,184

28,112

^[1]

352,814

Loss from equity method investment

8,727

^[1]

Depreciation and amortization

12,649

21,612

1,026

4,391

Impairment of right-of-use assets and property, plant and equipment

4,441

8,329

Gain on sale of the Huntsville manufacturing facility

(40,390)

^[1]

Provision for net realizable value of inventory

949

Amortization of premiums (discounts), net

(5,514)

(9,245)

Changes in operating assets and liabilities:

Accounts receivable

(3,045)

Inventory

497

Operating leases, net

(15,157)

(12,905)

Other assets

(15,449)

(4,187)

Accounts payable

(625)

2,668

Accrued expenses

(5,785)

10,733

Net cash used in operating activities

(208,511)

(175,709)

Cash flows from investing activities:

Purchases of investments

(285,012)

(261,709)

Maturities of investments

284,683

340,361

Proceeds (payments) relating to the sale of the Huntsville manufacturing facility, net

(697)

65,386

Purchases of property, plant and equipment

(171)

(1,468)

Net cash provided by (used in) investing activities

(1,197)

142,570

Cash flows from financing activities:

Payments of offering costs associated with issuance of common stock

(1,150)

Proceeds from issuance of TCG pre-funded warrant

30,000

Proceeds from sale of future royalties

15,000

Repurchase of common stock from Bristol-Myers Squibb

(3,000)

Proceeds from shares issued under equity compensation plans and TCG pre-funded warrant

866

118

Net cash provided by financing activities

180,566

42,118

Effect of foreign exchange rates on cash and cash equivalents

(4)

Net increase (decrease) in cash and cash equivalents

(29,136)

8,975

Cash and cash equivalents at beginning of year

44,252

35,277

Cash and cash equivalents at end of year

15,116

44,252

$ 15,116

Non-cash investing and financing activities:

Fair value of equity method investment in Gannet BioChem received in exchange for sale of Huntsville manufacturing facility

12,218

Transaction costs and net working capital adjustment for sale of Huntsville manufacturing facility included in accounts payable and accrued expenses

697

Supplemental disclosure of cash flow information:

Cash paid (refund) for income taxes, net

(195)

2025 Secondary Public Offering

Cash flows from financing activities:

Proceeds from offering, net

108,100

At-the-Market Offering

Cash flows from financing activities:

Proceeds from offering, net

$ 72,750

$ 0

[1]	All share and per share amounts have been retrospectively adjusted to reflect a one-for-fifteen reverse stock split (see Note 8).

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2025 USD ($)
Underwriting discounts, commissions and offering costs	$ 1,150
Secondary Offering
Underwriting discounts, commissions and offering costs	7,840
At-the-Market Offering
Underwriting discounts, commissions and offering costs	$ 2,460

Restructuring and Impairment - Sublease Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Restructuring Cost and Reserve [Line Items]
Book value in excess of fair value	$ 4,441
Total impairment of right-of-use assets and property, plant and equipment	4,441	$ 8,329
Reported Value Measurement
Restructuring Cost and Reserve [Line Items]
Property, plant and equipment and operating lease right-of-use assets	4,441	14,403
Property, Plant and Equipment
Restructuring Cost and Reserve [Line Items]
Total impairment of right-of-use assets and property, plant and equipment	624	1,042
Property, Plant and Equipment \| Reported Value Measurement
Restructuring Cost and Reserve [Line Items]
Property, plant and equipment and operating lease right-of-use assets	624	1,897
Operating Lease Right-of-Use Assets
Restructuring Cost and Reserve [Line Items]
Total impairment of right-of-use assets and property, plant and equipment	3,817	7,287
Operating Lease Right-of-Use Assets \| Reported Value Measurement
Restructuring Cost and Reserve [Line Items]
Property, plant and equipment and operating lease right-of-use assets	3,817	12,506
Fair Value, Level 3 \| Estimate of Fair Value Measurement
Restructuring Cost and Reserve [Line Items]
Property, plant and equipment and operating lease right-of-use assets	0	(6,074)
Fair Value, Level 3 \| Property, Plant and Equipment \| Estimate of Fair Value Measurement
Restructuring Cost and Reserve [Line Items]
Property, plant and equipment and operating lease right-of-use assets	0	(855)
Fair Value, Level 3 \| Operating Lease Right-of-Use Assets \| Estimate of Fair Value Measurement
Restructuring Cost and Reserve [Line Items]
Property, plant and equipment and operating lease right-of-use assets	$ 0	$ (5,219)

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Stock-Based Compensation - Schedule of Stock Option Activity Under Equity Incentive Plans (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2025 USD ($) $ / shares shares
Number of Shares
Outstanding, beginning balance (in shares) \| shares	2,203,927
Options granted (in shares) \| shares	529,888
Options exercised (in shares) \| shares	(76,013)
Options forfeited and canceled (in shares) \| shares	(196,083)
Outstanding, ending balance (in shares) \| shares	2,461,719
Weighted- Average Exercise Price per Share
Outstanding, beginning balance (in dollars per share) \| $ / shares	$ 83.73
Options granted (in dollars per share) \| $ / shares	43.6
Options exercised (in dollars per share) \| $ / shares	10.5
Options forfeited and canceled (in dollars per share) \| $ / shares	309.89
Outstanding, ending balance (in dollars per share) \| $ / shares	$ 59.34
Weighted- Average Remaining Contractual Life (in Years)
Weighted-Average Remaining Contractual Life, Outstanding	5 years 1 month 2 days
Aggregate Intrinsic Value, Outstanding \| $	$ 42,513
Number of Shares, Exercisable (in shares) \| shares	1,164,061
Weighted-Average Exercise Price Per Share, Exercisable (in dollars per share) \| $ / shares	$ 93.36
Weighted-Average Remaining Contractual Life, Exercisable	4 years 8 months 26 days
Aggregate Intrinsic Value, Exercisable \| $	$ 19,583

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Income Taxes Disclosure [Line Items]
Increase in valuation allowance	$ 33,300,000	$ 4,600,000
Operating loss carryforwards, subject to expiration	1,100,000,000
Unrecognized tax benefits, interest recognized	0	0
Unrecognized tax benefits, penalties recognized	0	$ 0
Federal
Income Taxes Disclosure [Line Items]
Operating loss carryforwards	$ 2,900,000,000
Operating loss carryforwards, expiration beginning date	Jan. 01, 2026
Tax credit carryforward, expiration beginning date	Jan. 01, 2026
Income tax research credits	$ 127,600,000
State
Income Taxes Disclosure [Line Items]
Operating loss carryforwards	$ 1,000,000,000
Operating loss carryforwards, expiration beginning date	Jan. 01, 2027
Income tax research credits	$ 61,400,000

Consolidated Financial Statement Details - Schedule of Other Current Assets (Details) - USD ($)
$ in Thousands

Dec. 31, 2025

Dec. 31, 2024

Prepaid research and development expenses

$ 20,514

$ 6,066

^[1]

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Interest and other non-trade receivables

16,540

1,947

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

1,779

1,609

Other prepaid expenses

Discontinued Operations and Disposal Groups [Abstract]

$ 2,195

$ 2,510

[1]	All share and per share amounts have been retrospectively adjusted to reflect a one-for-fifteen reverse stock split (see Note 8).

Insider Trading Policies and Procedures	12 Months Ended
Insider Trading Policies and Procedures	Dec. 31, 2025
Insider Trading Policies and Procedures [Line Items]
Insider Trading Policies and Procedures Adopted	true

Gain on Sale of the Huntsville Manufacturing Facility

12 Months Ended

Dec. 31, 2025

Gain on Sale of the Huntsville Manufacturing Facility

Note 11 — Gain on Sale of the Huntsville Manufacturing Facility

As discussed in Note 1, on December 2, 2024, we sold the Facility to Gannet BioChem. We recorded a gain on the sale based on the net cash proceeds received and our estimated fair value of our investment in Gannet BioChem, as compared to the carrying value of the Facility at closing. The gain was computed as follows (in thousands):


Cash proceeds at closing	$	71,167
Net working capital adjustment		(322	)
Fair value of equity method investment in Gannet BioChem - Level 3 of Fair Value Hierarchy		12,218
Gross cash and non-cash proceeds		83,063
Transaction costs		(6,155	)
Net proceeds	$	76,908


Accounts receivable	$	4,250
Inventory		14,655
Other current assets		864
Current liabilities		(1,354	)
Net working capital		18,415
Property, plant and equipment, net		11,569
Contract asset, net		6,534
Net assets sold	$	36,518


Net proceeds	$	76,908
Net assets sold		(36,518	)
Gain on asset sale	$	40,390

We estimated the fair value of the equity method investment using an option pricing method (OPM) based on the consideration paid for the preferred units. The OPM allows for the allocation of a company’s equity value among the various equity capital owners (preferred and common unitholders) and estimates the implied equity value of Gannet BioChem. The OPM uses the unitholders’ liquidation preferences to determine how proceeds from a liquidity event shall be distributed among the various ownership classes with an expected term to a liquidity event commensurate with a private equity investment. The following table lists the other Black-Scholes option-pricing model assumptions used to calculate the fair value of the equity method investment.


Risk-free interest rate	4.1	%
Dividend yield	0.0	%
Volatility factor	50.0	%

Organization and Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2025

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Organization

Nektar Therapeutics (Nektar, we) is a clinical stage, research-based drug discovery biopharmaceutical company headquartered in San Francisco, California and incorporated in Delaware, focused on discovering and developing innovative medicines in the field of immunotherapy. Within this growing field, we direct our efforts toward creating new immunomodulatory agents that selectively induce, amplify, attenuate or prevent immune responses in order to achieve desired therapeutic outcomes. Our pipeline of clinical-stage and preclinical-stage immunomodulatory agents targets the treatment of autoimmune diseases (e.g. rezpegaldesleukin and NKTR-0165 and-0166, respectively) and cancer (e.g. NKTR-255). We are conducting Phase 2b trials of rezpegaldesleukin in patients with moderate-to-severe atopic dermatitis which we initiated in October 2023 (the Phase 2b REZOLVE-AD trial) and in patients with severe-to-very severe alopecia areata which we initiated in March 2024 (the Phase 2b REZOLVE-AA trial). On February 24, 2025, we announced that we had entered into a collaboration agreement with TrialNet to evaluate rezpegaldesleukin in patients with new onset stage 3 type 1 diabetes mellitus in a Phase 2 study. TrialNet will conduct the study with funding from the National Institutes of Health, primarily through the Special Statutory Funding Program for Type 1 Diabetes through the National Institute of Diabetes and Digestive and Kidney Diseases. Nektar will supply rezpegaldesleukin for the study and will retain all rights to the rezpegaldesleukin program under the collaboration.

On June 24, 2025 and February 10, 2026, we announced data from the 16-week induction period and 36-week maintenance period, respectively, of the ongoing Phase 2b REZOLVE-AD trial being conducted in 393 patients.

On December 16, 2025, we announced data from the 36-week induction period of the ongoing Phase 2b REZOLVE-AA trial being conducted in 92 patients.

Our research and development activities have required significant ongoing investment to date and are expected to continue to require significant investment. As a result, we expect to continue to incur substantial losses and negative cash flows from operations in the future. We have financed our operations primarily through cash generated from licensing, collaboration and manufacturing agreements and financing transactions. At December 31, 2025, we had approximately $245.8 million in cash and investments in marketable securities.

As we continue our research and development activities, we will need additional cash to fund our operations. Accordingly, we may enter into new collaboration agreements or other similar transactions, and we may also seek financing transactions, which may include dilutive equity-based financings, such as an offering of our common stock. There can be no assurance that any additional collaboration agreements or financings will be available to us on commercially reasonable terms. We believe we have sufficient cash and investments in marketable securities to fund operations through at least the next twelve months from the date of the filing of these financial statements.

We filed a shelf registration statement on Form S-3 and a related prospectus (the April 2025 Shelf Registration Statement) that was declared effective by the Securities and Exchange Commission (the SEC) on April 1, 2025. Pursuant to the April 2025 Shelf Registration Statement, we may offer and sell common stock, preferred stock, debt securities, warrants and or units having an aggregate public offering price of up to $300.0 million. In connection with the filing of the Shelf Registration Statement, we also entered into an equity distribution agreement (the April 2025 ATM Sales Agreement) with Piper Sandler & Co. and BTIG, LLC, relating to the sale of our common stock having an aggregate offering price of up to $75.0 million (the April 2025 ATM Shares). The sales of the ATM shares could be made by any method permitted that is deemed to be an “at-the-market” equity offering as defined in Rule 415(a)(4) promulgated under the Securities Act, including sales made directly on or through Nasdaq or on any other existing trading market for our common stock. We have agreed to pay Piper Sandler & Co. and BTIG, LLC a commission equal to 3.0% of the gross sales price of all common stock sold through them as sales agents.

On July 2, 2025, pursuant to the April 2025 Shelf Registration Statement, we completed the sale and issuance of 4,893,618 shares of our common stock in an underwritten public offering (the 2025 Offering) at a price of $23.50 per share. The net proceeds to the Company from the 2025 Offering totaled approximately $107.2 million, after deducting underwriting discounts and commissions and offering costs. See Note 8 for additional information.

In September and October 2025, we issued 1,273,923 shares of our common stock under the April 2025 ATM Sales Agreement at a weighted average price of $58.87 per share for net proceeds of $72.5 million after deducting related commissions and offering costs. No shares remain available for issuance under the April 2025 ATM Sales Agreement.

On November 12, 2025, we filed a new registration statement on Form S-3ASR and a related prospectus (the November 2025 Shelf Registration), as a “well-known seasoned issuer,” as defined in Rule 405 under the Securities Act. The November 2025 Shelf Registration became automatically effective upon filing, and permits us to offer, from time to time, an unspecified amount of common stock, preferred stock, debt securities and warrants.

On February 13, 2026, we completed the sale and issuance of 7,637,931 shares of common stock at a price of $58.00 per share and 293,103 pre-funded warrants at price of $57.9999 per pre-funded warrant in an underwritten public offering (the 2026 Offering). The estimated net proceeds from the 2026 Offering totaled approximately $432.0 million, after deducting underwriting discounts and commissions and estimated offering expenses. See Note 8 for additional information.

On November 12, 2025, we also entered into a new equity distribution agreement (the November 2025 ATM Sales Agreement) with Piper Sandler & Co. and BTIG, LLC, relating to the sale of our common stock having an aggregate offering price of up to $110.0 million in an “at-the-market” offering (the November 2025 ATM Shares). As of December 31, 2025, no shares were issued under the November 2025 ATM Sales Agreement. From February 20, 2026 through March 11, 2026, we issued 639,131 shares of our common stock under the November 2025 ATM Sales Agreement at a weighted average price of $71.15 per share for net proceeds of $44.1 million after deducting related commissions of approximately $1.4 million.

Sale of Manufacturing Facility

On December 2, 2024, we completed the sale of our manufacturing facility located in Huntsville, Alabama (the Facility) and certain other manufacturing assets related thereto, including the assignment of our existing manufacturing and supply obligations, to Gannet BioChem, an affiliate of Ampersand Management LLC d/b/a Ampersand Capital Partners (Ampersand), via an Asset Purchase Agreement (the APA), for consideration of $64.7 million in cash, net of transaction costs, and an approximate 20% equity ownership at the time of close in Gannet BioChem. See Note 11 for additional information. As a result of the sale of the Facility, we no longer recognize product sales or cost of goods sold.

Basis of Presentation and Principles of Consolidation

We have prepared our Consolidated Financial Statements pursuant to U.S. generally accepted accounting principles (U.S. GAAP) and the rules and regulations of the Securities and Exchange Commissions.

Our Consolidated Financial Statements include the financial position, results of operations and cash flows of our wholly-owned subsidiaries. In determining whether we are the primary beneficiary of a variable interest entity, we consider whether we have both the power to direct activities of the entity that most significantly impact the entity’s economic performance and the obligation to absorb losses of, or the right to receive benefits from, the entity that could potentially be significant to that entity. We do not have any interests in any variable interest entities of which we are the primary beneficiary. We have eliminated all intercompany accounts and transactions in consolidation.

Our Consolidated Financial Statements are denominated in U.S. dollars. Accordingly, changes in exchange rates between the applicable foreign currency and the U.S. dollar will affect the translation of each foreign subsidiary’s financial results into U.S. dollars for purposes of reporting our consolidated financial results.

Our comprehensive loss consists of our net loss plus our foreign currency translation gains and losses (to the extent recognized in other comprehensive income (loss)) and unrealized holding gains and losses on available-for-sale securities. There were no significant reclassifications out of accumulated other comprehensive income (loss) to the statements of operations during the periods presented. We include translation gains and losses in accumulated other comprehensive income (loss) in the stockholders’ equity section of our Consolidated Balance Sheets. However, if we have concluded that we have substantially liquidated the entity, such as for our subsidiary in India, we recognize subsequent translation gains and losses in other income (expense) in our Consolidated Statements of Operations.

Use of Estimates

The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Accounting estimates and assumptions are inherently uncertain.

Actual results could differ materially from those estimates and assumptions. Our estimates include those related to the selling prices of performance obligations and amounts of variable consideration in collaboration agreements, royalty revenue, and other assumptions required for revenue recognition as described further below; the determination of our ability to exercise control or significant influence over our equity method investee; the fair value and impairment of investments in marketable securities, equity method investment, and long-lived assets; contingencies, accrued clinical trial, contract manufacturing and other expenses; income taxes; non-cash royalty revenue and non-cash interest expense from our liabilities related to our sales of future royalties; our assumptions used in stock-based compensation; and ongoing litigation, among other estimates. We base our estimates on historical experience and on other assumptions, including assumptions as to future events, that management believes are reasonable under the circumstances. These estimates form the basis for making judgments about the carrying values of assets and liabilities when these values are not readily apparent from other sources. As appropriate, we assess estimates each period, update them to reflect current information, and generally reflect any changes in estimates in the period first identified.

Fair Value Measurements

The recorded amounts of certain financial instruments, including cash and cash equivalents, accounts receivable, accounts payable and accrued liabilities approximate their fair values due to their relatively short maturities. We record available-for-sale investments and cash equivalents at their estimated fair values, which are based on market prices from a variety of industry standard data providers and generally represent quoted prices for similar assets in active markets or have been derived from observable market data.

Certain assets and liabilities are reported on a recurring basis at fair value, and certain assets and liabilities are subsequently adjusted to their fair values, in accordance with the fair value hierarchy established in ASC 820-10, Fair Value Measurements and Disclosures (ASC 820). ASC 820 defines fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The fair value hierarchy of ASC Topic 820 requires an entity to maximize the use of observable inputs when measuring fair value and classifies those inputs into three levels:

Level 1 — Quoted prices in active markets for identical assets or liabilities.

Level 2 — Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices for identical or similar assets or liabilities in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. For the years ended December 31, 2025 and 2024, there were no transfers between Level 1 and Level 2 of the fair value hierarchy.

Level 3 — Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

Related Parties

Transactions between related parties are considered to be related party transactions even though they may not be given accounting recognition. ASC 850, Related Party Disclosures (ASC 850) requires that transactions with related parties that would make a difference in decision making shall be disclosed so that users of the financial statements can evaluate their significance. Please see Note 4 regarding our related party transactions with Gannet BioChem.

Cash, Cash Equivalents, and Investments in Marketable Securities

We consider all investments in marketable securities with an original maturity of 90 days or less when purchased to be cash equivalents. We classify investments in securities with remaining maturities of less than one year, or where our intent is to use the investments to fund current operations or to make them available for current operations, as short-term investments. We classify investments in securities with remaining maturities of over one year as long-term investments.

Our cash and investments are held or issued by financial institutions that management believes are of high credit quality. However, we are exposed to credit risk in the event of default by the third parties that hold or issue such assets. Our investment policy limits investments to fixed income securities denominated and payable in U.S. dollars such as corporate bonds, corporate commercial paper, U.S. government obligations, and money market funds and places restrictions on maturities and concentrations by type and issuer.

For our available-for-sale securities, we have significant concentrations of issuers in the banking and financial services industry. While our investment policy requires that we only invest in highly-rated securities and limit our exposure

to any single issuer, a variety of factors may materially affect the financial condition of issuers. Additionally, pursuant to our investment policy, we may sell securities before maturity if the issuer’s credit rating has been downgraded below our minimum credit rating requirements, which may result in a loss on the sale. Accordingly, if factors result in downgrades below our minimum credit rating requirements and if we decide to sell these securities, we may experience losses on such sales.

Investments are designated as available-for-sale and are carried at fair value with unrealized gains and losses reported in stockholders’ equity as accumulated other comprehensive income (loss). We review our portfolio of available-for-sale debt securities, using both quantitative and qualitative factors, to determine if declines in fair value below amortized cost have resulted from a credit-related loss or other factors. If the decline in fair value is due to credit-related factors, we recognize a loss in our Consolidated Statements of Operations, whereas if the decline in fair value is not due to credit-related factors, we recognize the loss in other comprehensive income (loss).

We include coupon interest on securities classified as available-for-sale, as well as amortization of premiums and accretion of discounts to maturity, in interest income. The cost of securities sold is based on the specific identification method.

Accounts Receivable and Significant Customer Concentrations

Our customers are primarily pharmaceutical and biotechnology companies with whom we have multi-year arrangements. Before the sale of the Facility, our accounts receivable balance primarily contained trade receivables from product sales. We have not recorded provisions for credit losses for any of the periods presented. Accounts receivable at December 31, 2025 and December 31, 2024 are immaterial due to the sale of the Facility.

Inventory and Significant Supplier Concentrations

Before the sale of Facility, we manufactured inventory upon receipt of firm purchase orders from our partners, and we manufactured certain intermediate work-in-process materials and purchased raw materials based on purchase forecasts from our partners. Inventory included direct materials, direct labor, and manufacturing overhead, and we determined cost on a first-in, first-out basis for raw materials and on a specific identification basis for work-in-process and finished goods. We valued inventory at the lower of cost or net realizable value, and we wrote down defective or excess inventory to net realizable value based on historical experience or projected usage. We expensed inventory related to our research and development activities when we purchased or manufactured it. We have no inventory balance at December 31, 2025 and December 31, 2024 due to the sale of the Facility.

We are dependent on our suppliers and contract manufacturers to provide raw materials and drugs of appropriate quality and reliability and to meet applicable contract and regulatory requirements. In certain cases, we rely on single sources of supply of one or more critical materials. As a result of the sale of the Facility, we are dependent on Gannet BioChem for the supply of the polyethylene glycol reagents (PEG reagents) used in the manufacture of rezpegaldesleukin and NKTR-255. Consequently, in the event that supplies are delayed or interrupted for any reason, our ability to develop and produce our drug candidates could be significantly impaired, which could have a material adverse effect on our business, financial condition and results of operations.

Reverse Stock Split

On June 6, 2025, we filed a Certificate of Amendment to the Certificate of Incorporation, or the Reverse Stock Split Amendment, to effect a reverse stock split of Nektar’s Common Stock at a ratio of one-for-fifteen, effective June 8, 2025. No fractional shares of common stock were issued as a result of the Reverse Stock Split. All share and per share figures in these financial statements have been adjusted to give retrospective effect to the Reverse Stock Split. See Note 8 for additional information.

Treasury Stock

We record treasury stock activities under the cost method. Treasury stock is included in authorized and issued shares but excluded from outstanding shares. The re-issuance of treasury stock is accounted for on a first-in, first-out basis and any differences between the cost of treasury stock and the re-issuance proceeds are charged or credited to additional paid-in capital. In connection with the 2025 Offering, we re-issued all shares held in treasury stock. See Note 8 for additional information.

Long-Lived Assets

We report property and equipment at cost, net of accumulated depreciation. We capitalize major improvements and expense maintenance and repairs as incurred. We generally recognize depreciation on a straight-line basis. We depreciate manufacturing, laboratory and other equipment over their estimated useful lives of generally three to ten years, depreciate buildings over the estimated useful life of generally twenty years and amortize leasehold improvements over the shorter of the estimated useful lives or the remaining term of the related lease.

We assess the impairment of long-lived assets whenever events or changes in business circumstances indicate that the carrying amounts of the assets may not be fully recoverable. In the case of property and equipment and right-of-use assets for our leases, we determine whether there has been an impairment by comparing the carrying value of the asset to the anticipated undiscounted net cash flows associated with the asset. If such cash flows are less than the carrying value, we write down the asset to its fair value, which may be measured as anticipated net cash flows associated with the asset, discounted at a rate that we believe a market participant would utilize to reflect the risks associated with the cash flows, such as credit risk.

See Note 10 for additional information regarding the impairment charges we recorded for our leased facilities and certain property and equipment.

Leases

We determine if an arrangement contains a lease at the inception of the arrangement. Right-of-use assets represent our right to use an underlying asset for the lease term, and lease liabilities represent our obligation to make lease payments arising from the lease. We recognize operating lease right-of-use assets and liabilities at the lease commencement date based on the present value of lease payments over the expected lease term. In determining the present value of lease payments, we use our incremental borrowing rate based on the information available at the lease commencement date. Our expected lease terms may include options to extend or terminate the lease when it is reasonably certain that we will exercise any such options. We have elected to recognize lease incentives, such as tenant improvement allowances, at the lease commencement date as a reduction of the right-of-use asset and lease liability until paid to us by the lessor to the extent that the lease provides a specified fixed or maximum level of reimbursement and we are reasonably certain to incur reimbursable costs at least equaling such amounts.

We have elected the practical expedient to account for the lease and non-lease components, such as common area maintenance charges, as a single lease component for our facilities leases, and elected the short-term lease recognition exemption for our short-term leases, under which we do not recognize lease liabilities and right-of-use assets for leases with an original term of twelve months or less.

We recognize lease expense for our operating leases on a straight-line basis over the expected lease term. However, if we recognize an impairment of our right-of-use assets, the subsequent lease expense of such lease is recognized on an accelerated basis as lease expense includes the recognition of accretion expense on our lease liability, which is higher in earlier periods due to the higher lease liability, and straight-line amortization of the remaining post-impairment right-of-use asset.

Please see Note 5 for additional information regarding our leases.

Collaborative Arrangements

We enter into collaboration arrangements with pharmaceutical and biotechnology collaboration partners, under which we may grant licenses to our collaboration partners to further develop and commercialize one of our drug candidates, either alone or in combination with the collaboration partners’ compounds. We may also perform research, development, manufacturing and supply activities under our collaboration agreements. Consideration under these contracts may include an upfront payment, development and regulatory milestones and other contingent payments, expense reimbursements, royalties based on net sales of approved drugs, and commercial sales milestone payments. Additionally, these contracts may provide options for the customer to purchase additional contract research and development services under separate contracts.

When we enter into collaboration agreements, we assess whether the arrangements fall within the scope of ASC 808, Collaborative Arrangements (ASC 808) based on whether the arrangements involve joint operating activities and whether both parties have active participation in the arrangement and are exposed to significant risks and rewards of the arrangement. To the extent that the arrangement falls within the scope of ASC 808, we assess whether the payments between us and our collaboration partner fall within the scope of other accounting literature. If we conclude that payments from the collaboration partner to us represent consideration from a customer, such as license fees and contract research and development activities, we account for those payments within the scope of ASC 606, Revenue from Contracts with Customers (ASC 606). However, if we conclude that our collaboration partner is not a customer for certain activities and associated payments, such as for certain collaborative research, development, manufacturing and commercial activities, we present such payments as a reduction of research and development expense or general and administrative expense, based on where we present the underlying expense.

Revenue Recognition

For elements of those arrangements that we determine should be accounted for under ASC 606, we assess which activities in our collaboration agreements are performance obligations that should be accounted for separately and determine the transaction price of the arrangement, which includes the assessment of the probability of achievement of future milestones and other potential consideration. For arrangements that include multiple performance obligations, such as granting a license or performing contract research and development activities or participation on joint steering or other committees, we allocate upfront and milestone payments under a relative standalone selling price method. Accordingly, we develop assumptions that require judgment to determine the standalone selling price for each performance obligation identified in the contract. These key assumptions may include revenue forecasts, clinical development timelines and costs, discount rates and probabilities of clinical and regulatory success.

Product sales

As a result of the sale of the Facility, we no longer recognize product sales of PEG reagents.

Before the sale of the Facility, product sales were primarily derived from manufacturing and supply agreements we entered into with our customers. We have assessed our manufacturing and supply arrangements and have generally determined that they provided the customer an option to purchase our proprietary PEG reagents. Accordingly, we treated each purchase order as a discrete exercise of the customer’s option (i.e. a separate contract) rather than as a component of the overall arrangement. The pricing for the manufacturing and supply was generally at a fixed price. The “take or pay” arrangement signed with UCB during 2024 resulted in recognition based on a single sales price over multiple years. See Note 9 for additional details.

We invoiced and recognized product sales when title and risk of loss passed to the customer, which generally occurred upon shipment. Customer payments were generally due 30 days from receipt of an invoice. We tested our products for adherence to technical specifications before shipment; accordingly, we have not experienced any significant returns from our customers. We recognized costs related to shipping and handling of product to customers in cost of goods sold.

Non-cash royalty revenue

Generally, for our collaboration arrangements that include sales-based royalties, we have granted our collaboration partner a license to our intellectual property. Pursuant to these arrangements, our collaboration partners are typically obligated to pay a royalty that is based on the net sales of their approved drugs that are sold in the countries where we have intellectual property rights covering their drugs. We have sold our rights to receive sales-based royalties for CIMZIA®, MIRCERA®, MOVANTIK®, ADYNOVATE® and REBINYN® as further described in Note 6. For collaboration arrangements that include sales-based royalties, we have concluded that the license is the predominant item to which the royalties relate, which include commercial milestone payments based on the level of sales. Accordingly, we recognize royalty revenue when the underlying sales occur based on our best estimates of sales of the drugs. Our aggregate non-cash

royalty revenue of $54.9 million and $64.3 million for the years ended December 31, 2025 and 2024, respectively, represents revenue for granting licenses for which we had satisfied in prior periods.

License, collaboration and other revenue

License Grants: For collaboration arrangements that include a grant of a license to our intellectual property, we consider whether the license grant is distinct from the other performance obligations included in the arrangement. Generally, we would conclude that the license is distinct if the customer is able to benefit from the license with the resources available to it. For licenses that are distinct, we recognize revenues from non-refundable, upfront payments and other consideration allocated to the license when the license term has begun and we have provided all necessary information regarding the underlying intellectual property to the customer, which generally occurs at or near the inception of the arrangement.

Milestone Payments: At the inception of the arrangement and at each reporting date thereafter, we assess whether we should include any milestone payments or other forms of variable consideration in the transaction price, based on whether a significant reversal of revenue previously recognized is not probable upon resolution of the uncertainty. Since milestone payments may become payable to us upon the initiation of a clinical study, filing for or receipt of regulatory approval or the first commercial sale of a product, we review the relevant facts and circumstances to determine when we should update the transaction price, which may occur before the triggering event. When we do update the transaction price for milestone payments, we allocate it on a relative standalone selling price basis and record revenue on a cumulative catch-up basis, which results in recognizing revenue for previously satisfied performance obligations in such period. If we update the transaction price before the triggering event, we recognize the increase in the transaction price as a contract asset. Our partners generally pay development milestones after achievement of the triggering event.

Research and Development Services: For amounts allocated to our research and development obligations in a collaboration arrangement, we recognize revenue over time using a proportional performance model, representing the transfer of goods or services as we perform activities over the term of the agreement.

Research and Development Expense

Research and development costs are expensed as incurred and include salaries, benefits and other operating costs such as outside services, supplies and allocated overhead costs.

We record an accrued expense for the estimated unbilled costs of our clinical study activities performed by third parties. The financial terms of these agreements are subject to negotiation, vary from contract to contract and may result in uneven payment flows to our vendors. Payments under the contracts depend on factors such as the achievement of certain events, successful enrollment of patients and completion of certain clinical trial activities. We generally recognize costs associated with the start-up and reporting phases of the clinical trials as incurred. We generally accrue costs associated with the treatment phase of clinical trials based on the estimated activities performed by our third-party vendors, including our contract research organizations. In specific circumstances, such as for certain time-based costs, we recognize clinical trial expenses ratably over the service period, as we believe that this methodology may be more reflective of the timing of costs incurred.

We capitalize advance payments for goods or services that will be used or rendered for future research and development activities and recognize expense as the related goods are delivered or services performed.

Restructuring

In April 2022 and April 2023, we announced certain restructuring plans (the 2022 Restructuring Plan and the 2023 Restructuring Plan, respectively), pursuant to which we terminated significant portions of our workforce and decided to sublease all of our leased premises in San Francisco, California, including our office space on Third St. (Third St. Facility) and our office and laboratory space on Mission Bay Blvd. South (Mission Bay Facility).

We recognize restructuring charges related to reorganization plans that have been committed to by management when liabilities have been incurred. In connection with these activities, we record restructuring charges at fair value for contract termination costs incurred when we cancel the contract in accordance with its terms, or for costs to be incurred over the remaining contract term without economic benefit to us at the cease-use date. See Note 10 for additional information.

Non-cash Interest Expense on Liabilities Related to the Sales of Future Royalties

Interest expense on liabilities related to the sales of future royalties is imputed on the unamortized portion using the effective interest method. We periodically assess the estimated royalty payments under our licensees, and, as the amount or timing of such payments of these estimates change, we prospectively adjust the imputed interest rate and the related amortization of the respective liability. The actual interest rate will be affected by the timing of the royalty payments and changes in the forecasted revenue.

Equity Method Investment

Our investment in Gannet BioChem is considered a variable interest entity for which we are not the primary beneficiary. We use the equity method of accounting to account for our investment in Gannet BioChem, which is an entity that we do not control, but have the ability to exert significant influence. Judgments regarding the level of influence over the equity method investment include consideration of key factors such as our ownership interest, representation on the board of directors or participation in policy-making decisions.

Under the equity method of accounting, our investment in Gannet BioChem was initially recorded at fair value on our Consolidated Balance Sheets. The carrying value of the investment is subsequently adjusted based on our share of the net income or loss of the entity which we present as gain or loss from equity method investment in our Consolidated Statements of Operations. We record our share of the equity method investment’s results of operations on a three-month lag basis, as further disclosed in Note 4.

Due to Ampersand’s right to receive a cumulative preferred dividend at a certain annual rate of return and return of capital before any distributions are made to us as further disclosed in Note 4, we record our gain or loss on our investment in Gannet BioChem under the hypothetical liquidation at book value (HLBV) method.

The HLBV method is a balance sheet approach that calculates the change in the hypothetical amount Ampersand and we would be entitled to receive if Gannet BioChem were liquidated at book value at the end of each period, adjusted for any contributions made and distributions received during the period, as well as basis differences between the initial fair value of our investment in Gannet BioChem and our claim on the net assets of Gannet BioChem. Our maximum exposure to loss in Gannet BioChem is limited to the carrying value of our investment. Loss from our investment in Gannet BioChem of $8.7 million has been recorded for the year ended December 31, 2025.

We evaluate our equity method investment at the end of each reporting period to determine whether events or changes in business circumstances indicate that the carrying value of the investment may not be recoverable. This evaluation consists of several qualitative and quantitative factors that may include recent financial results, projected financial results and operating trends of the investees and other publicly available information that may affect the value of our investment.

Stock-Based Compensation

Stock-based compensation arrangements include grants of stock options and restricted stock units (RSUs) under our equity incentive plans, as well as shares issued under our Employee Stock Purchase Plan (ESPP), through which employees may purchase our common stock at a discount to the market price.

We expense the grant date fair value of stock-based compensation on a straight-line basis over the requisite service periods in our Consolidated Statements of Operations and recognize forfeitures as they occur. For options and RSUs that vest upon the achievement of performance milestones, we recognize expense provided that we believe that the performance milestones are probable of achievement, and we estimate the vesting period based on our evaluation of the estimated date of achievement of these milestones. We report expense amounts in cost of goods sold, research and development expense, and general and administrative expense based on the function of the applicable employee. We estimate the grant date fair value of our stock-based compensation awards as follows:

•

Stock options - We use the Black-Scholes option pricing model for the respective grant to determine the grant date fair value of stock options and common stock issued under the Company’s equity incentive plans or purchased under the ESPP. The Black-Scholes option pricing model requires the input of assumptions, including but not limited to, the expected term of the options, which we may estimate based on actual and projected employee stock option exercise behaviors, and our stock price volatility over the term of the awards.

•

RSUs - The fair value of an RSU is equal to the closing price of our common stock on the grant date.

Income Taxes

We account for income taxes under the liability method. Under this method, we determine deferred tax assets and liabilities based on differences between the financial reporting and tax reporting bases of assets and liabilities, measured using laws and enacted tax rates that we expect to be in effect when we expect the differences to reverse. Realization of deferred tax assets is dependent upon future earnings, the timing and amount of which are uncertain. We record a valuation allowance against deferred tax assets to reduce their carrying value to an amount that is more likely than not to be realized. When we establish or reduce the valuation allowance related to the deferred tax assets, our provision for income taxes will increase or decrease, respectively, in the period we make such determination.

We utilize a two-step approach to recognize and measure uncertain tax positions. The first step is to evaluate the tax position for recognition by determining if the weight of available evidence indicates that it is more likely than not that the position will be sustained upon tax authority examination, including resolution of related appeals or litigation processes, if any. The second step is to measure the tax benefit as the largest amount of benefit, determined on a cumulative probability basis, that is more than 50% likely of being realized upon ultimate settlement.

For the years ended December 31, 2025 and 2024, our income tax benefit was immaterial.

Net Loss Per Share

For all periods presented in the Consolidated Statements of Operations, the net loss available to common stockholders is equal to the reported net loss. We calculate basic net loss per share based on the weighted-average number of common shares outstanding, including the TCG Pre-funded Warrant, during the periods presented. Before the exercise of the TCG Pre-funded Warrant, shares of common stock underlying the TCG Pre-funded Warrant were considered outstanding for the purposes of computing basic net loss per share because the shares were issuable for little consideration, were fully vested and were exercisable after the original issuance date. For the years ended December 31, 2025 and 2024, basic and diluted net loss per share are the same due to our net losses and the requirement to exclude potentially dilutive securities which would have an antidilutive effect on net loss per share. We excluded shares underlying the weighted average outstanding stock options and RSUs, as follows:


	Year Ended December 31,
	2025		2024
Potentially dilutive securities		2,260,593		1,788,719

Comprehensive Loss

Comprehensive loss is the change in stockholders’ equity from transactions and other events and circumstances other than those resulting from investments by stockholders and distributions to stockholders. Our comprehensive loss includes our net loss, gains and losses from the foreign currency translation of the assets and liabilities of our foreign subsidiaries, and unrealized gains and losses on investments in available-for-sale securities.

Recent Accounting Pronouncements

In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, which will require incremental income tax disclosures on an annual basis for all public entities. The amendments require that public business entities disclose specific categories in the rate reconciliation and provide additional information for reconciling items meeting a quantitative threshold. The amendments also require disclosure of income taxes paid to be disaggregated by jurisdiction, and disclosure of income tax expense disaggregated by federal, state, and foreign. ASU 2023-09 is effective for annual reporting beginning with the fiscal year ending December 31, 2025. We have adopted ASU-2023-09 on a prospective basis for the year ended December 31, 2025. Please refer to Note 13 for further details.

In November 2024, the FASB issued ASU No. 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses, an accounting standard update that requires the Company to disclose more detailed information about the types of expenses (including employee compensation, depreciation, and amortization) included in each relevant income statement expense caption. In January 2025, the FASB issued ASU 2025-01, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40): Clarifying the Effective Date, to clarify the effective date of ASU 2024-03. The ASU is effective for fiscal years beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027. Early adoption is permitted. We are currently evaluating the incremental disclosures that will be required in our consolidated financial statements.

Organization and Summary of Significant Accounting Policies (Details)

1 Months Ended

2 Months Ended

12 Months Ended

Feb. 13, 2026

USD ($)

$ / shares

Nov. 12, 2025

USD ($)

Jul. 02, 2025

USD ($)

$ / shares

Jun. 08, 2025

Jun. 06, 2025

Dec. 02, 2024

USD ($)

Mar. 11, 2026

USD ($)

$ / shares

Oct. 31, 2025

USD ($)

$ / shares

Dec. 31, 2025

USD ($)

Dec. 31, 2024

USD ($)

Organization And Summary Of Significant Accounting Policies [Line Items]

Cash and investments in marketable securities

$ 245,752,000

$ 269,095,000

Aggregate maximum public offering amount

300,000,000

Proceeds from issuance of TCG pre-funded warrant

30,000,000

Commissions costs

1,150,000

Inventory

$ 0

Reverse stock split

Reverse Stock Split Amendment, to effect a reverse stock split of Nektar’s Common Stock at a ratio of one-for-fifteen, effective June 8, 2025.

one-for-fifteen reverse stock split

Accounts receivable, credit loss expense (reversal)

0.07

Revenue

$ 55,232,000

$ 98,427,000

^[1]

$ 0

ASU 2023-09

Organization And Summary Of Significant Accounting Policies [Line Items]

Change in Accounting Principle, Accounting Standards Update, Adopted [true false]

true

Change in Accounting Principle, Accounting Standards Update, Adoption Date

Dec. 31, 2025

Gannet BioChem

Organization And Summary Of Significant Accounting Policies [Line Items]

Loss from our investment

$ 8,700,000

Common Stock

Organization And Summary Of Significant Accounting Policies [Line Items]

Common Stock | Subsequent Event

0.07

Organization And Summary Of Significant Accounting Policies [Line Items]

7,637,931

Common Stock | Underwritten Public Offering

$ 58

Organization And Summary Of Significant Accounting Policies [Line Items]

4,893,618

Net proceeds from issuance of common stock

$ 23.5

$ 107,200,000

NonCash Royalties

Organization And Summary Of Significant Accounting Policies [Line Items]

Revenue

$ 54,900,000

$ 64,300,000

Buildings

Organization And Summary Of Significant Accounting Policies [Line Items]

Property and equipment estimated useful lives

20 years

Minimum | Manufacturing equipment

Organization And Summary Of Significant Accounting Policies [Line Items]

Property and equipment estimated useful lives

3 years

Maximum | Manufacturing equipment

Organization And Summary Of Significant Accounting Policies [Line Items]

Property and equipment estimated useful lives

10 years

Asset Purchase Agreement | Asset Acquisition By Ampersand Capital Partners

Organization And Summary Of Significant Accounting Policies [Line Items]

Proceeds from sale of assets

$ 64,700,000

Ownership interest received

20.00%

Sales Agreement

Organization And Summary Of Significant Accounting Policies [Line Items]

Aggregate maximum public offering amount

$ 75,000,000

Percentage of gross sale of common stock sold through sales agents commission rate

3.00%

November 2025 ATM Sales Agreement | Common Stock

Organization And Summary Of Significant Accounting Policies [Line Items]

Aggregate maximum public offering amount

$ 110,000,000

November 2025 ATM Sales Agreement | Common Stock | Subsequent Event

Organization And Summary Of Significant Accounting Policies [Line Items]

639,131

Net proceeds from issuance of common stock

$ 71.15

$ 44,100,000

Commissions costs

$ 1,400,000

April 2025 ATM Sales Agreement | Common Stock

Organization And Summary Of Significant Accounting Policies [Line Items]

1,273,923

Net proceeds from issuance of common stock

$ 58.87

$ 72,500,000

Pre-Funded Warrant | Underwritten Public Offering | Subsequent Event

Organization And Summary Of Significant Accounting Policies [Line Items]

Number of warrants issued to be purchase common shares | shares

293,103

Proceeds from issuance of TCG pre-funded warrant

$ 432,000,000

Shares issued, price per share | $ / shares

$ 57.9999

[1]	All share and per share amounts have been retrospectively adjusted to reflect a one-for-fifteen reverse stock split (see Note 8).

Operating Leases (Tables)

12 Months Ended

Dec. 31, 2025

Leases [Abstract]

Schedule of Lease Expense

The components of lease expense, which we include in general and administrative expense in our Consolidated Statements of Operations, were as follows (in thousands):


	Year Ended December 31,
	2025		2024
Operating lease expense	$	7,155	$	8,723
Variable lease expense		7,905		9,000
Total lease expense	$	15,060	$	17,723

Schedule of Future Minimum Lease Payments for Operating Leases

As of December 31, 2025, the maturities of our operating lease liabilities were as follows (in thousands):


Year ending December 31,
2026	$	21,096
2027		23,682
2028		24,427
2029		25,195
2030 and thereafter		2,108
Total lease payments		96,508
Less: portion representing interest		(10,757	)
Operating lease liabilities		85,751
Less: current portion		(20,495	)
Operating lease liabilities, less current portion	$	65,256

Schedule of Maturities of Operating Lease Receivables from Subleases

As of December 31, 2025, maturities of our operating lease receivables from subleases for each of the next five years and thereafter were as follows:


Year ending December 31,
2026	$	1,670
2027		1,729
2028		1,788
2029		1,846
2030 and thereafter		—
Gross lease receivable	$	7,033

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2025

Share-Based Payment Arrangement [Abstract]

Schedule of Stock-Based Compensation Expense

We recognize total stock-based compensation expense in our Consolidated Statements of Operations as follows (in thousands):


	Year Ended December 31,
	2025		2024
Cost of goods sold	$	—	$	1,946
Research and development		5,444		8,161
General and administrative		7,205		11,505
Total stock-based compensation	$	12,649	$	21,612

Schedule of Black-Scholes Option-Pricing Model Assumptions Used to Calculate Fair Value of Employee Stock Options

The following table lists the Black-Scholes option-pricing model assumptions used to calculate the fair value of employee and director stock options, as well as the resulting grant-date fair value:


	Year Ended December 31,
	2025			2024
Average risk-free interest rate		3.8	%		4.2	%
Dividend yield		0.0	%		0.0	%
Average volatility factor		104.9	%		91.7	%
Weighted-average expected life	5.2 years			5.1 years
Weighted-average grant-date fair value of options granted	$	34.48		$	11.42

Schedule of Stock Option Activity Under Equity Incentive Plans

The table below presents a summary of stock option activity under our equity incentive plans (in thousands, except for share, per share, and contractual life information):


						Weighted-
				Weighted-		Average
				Average		Remaining
	Number			Exercise		Contractual		Aggregate
	of			Price		Life		Intrinsic
	Shares			per Share		(in Years)		Value(1)
Outstanding at December 31, 2024		2,203,927		$	83.73
Options granted		529,888			43.60
Options exercised		(76,013	)		10.50
Options forfeited & canceled		(196,083	)		309.89
Outstanding at December 31, 2025		2,461,719		$	59.34		5.09	$	42,513

Exercisable at December 31, 2025		1,164,061		$	93.36		4.74	$	19,583

(1)

Aggregate intrinsic value represents the difference between the exercise price of the option and the closing market price of our common stock on December 31, 2025.

Schedule of Restricted Stock Unit Award Activity

A summary of RSU award activity is as follows:


				Weighted-
				Average
				Grant
				Date Fair
	Units Issued			Value
Unvested at December 31, 2024		101,524		$	105.31
Granted		195,943			43.87
Vested and released		(82,085	)		87.03
Forfeited and canceled		(7,282	)		99.68
Unvested at December 31, 2025		208,100		$	54.01

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2025

Equity [Abstract]

Schedule of Shares of Common Stock Reserved for Future Issuance

Shares of common stock reserved for future issuance are as follows:


	December 31,
	2025		2024
Stock options and RSUs outstanding		2,669,819		2,305,451
Shares reserved for TCG Pre-funded Warrant		—		1,666,667
Shares available for future grant under the 2017 Performance Incentive Plan		353,240		551,727
Shares available for future grant under the 2025 Inducement Plan		231,690		—
Shares available for issuance under the employee stock purchase plan		45,858		47,383
Total common stock reserved for issuance		3,300,607		4,571,228

Liabilities Related to the Sales of Future Royalties (Tables)

12 Months Ended

Dec. 31, 2025

Schedule of Liability Related to Potential Future Royalties

The following table shows the activity within the liability account of each arrangement (in thousands):


	Year-Ended December 31, 2025									Period from inception to December 31, 2025
	2012 Purchase and Sale Agreement			2020 Purchase and Sale Agreement			Total			2012 Purchase and Sale Agreement			2020 Purchase and Sale Agreement			Total
Liabilities related to the sales of future royalties—beginning balance	$	7,197		$	85,522		$	92,719		$	—		$	—		$	—
Royalty monetization proceeds		—			—			—			124,000			165,000			289,000
Non-cash royalty revenue		(7,894	)		(47,038	)		(54,932	)		(388,622	)		(202,743	)		(591,365	)
Non-cash interest expense		2,767			23,417			26,184			253,170			99,644			352,814
Payments to RPI		—			—			—			(10,000	)		—			(10,000	)
Loss on revaluation of liability related to the sale of future royalties		—			—			—			23,522			—			23,522
Liabilities related to the sales of future royalties – ending balance		2,070			61,901			63,971			2,070			61,901			63,971
Less: unamortized transaction costs		—			(814	)		(814	)		—			(814	)		(814	)
Liabilities related to the sales of future royalties, net	$	2,070		$	61,087		$	63,157		$	2,070		$	61,087		$	63,157

Segment Reporting - Additional Information (Details) - Segment	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Segment Reporting Information [Line Items]
Number of operating business segment	1
Segment Reporting, CODM, Individual Title and Position or Group Name [Extensible Enumeration]	srt:ChiefExecutiveOfficerMember
Segment Reporting, CODM, Profit (Loss) Measure, How Used, Description	The CODM assesses the performance of the Company and decides how to allocate resources based upon net loss that is also reported within the Consolidated Statements of Operations. The measure of segment assets that is reviewed by the CODM is reported within the Consolidated Balance Sheet as total assets.
Revenue \| UCB \| Customer Concentration Risk
Segment Reporting Information [Line Items]
Percentage revenue from customers	14.00%	39.00%
Revenue \| Baxalta Incorporated Or Takeda P L C \| Customer Concentration Risk
Segment Reporting Information [Line Items]
Percentage revenue from customers	45.00%	18.00%
Revenue \| Astra Zeneca Ab \| Customer Concentration Risk
Segment Reporting Information [Line Items]
Percentage revenue from customers	37.00%	17.00%
Revenue \| Pfizer \| Customer Concentration Risk
Segment Reporting Information [Line Items]
Percentage revenue from customers		12.00%
Revenue \| Roche \| Customer Concentration Risk
Segment Reporting Information [Line Items]
Percentage revenue from customers		10.00%

CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2025 USD ($)
2025 Secondary Public Offering
Underwriting discounts	$ 6,900
At-the-Market Offering
Commissions	$ 2,250

Cash and Investments in Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2025

Fair Value Disclosures [Abstract]

Schedule of Cash and Investments in Marketable Securities, Including Cash Equivalents

Cash and investments in marketable securities, including cash equivalents, are as follows (in thousands):


	Estimated Fair Value at
	December 31,		December 31,
	2025		2024
Cash and cash equivalents	$	15,116	$	44,252
Short-term investments		230,636		210,974
Long-term investments		—		13,869
Total cash and investments in marketable securities	$	245,752	$	269,095

Schedule of Portfolio of Cash and Investments in Marketable Securities

Our portfolio of cash and investments in marketable securities includes (in thousands):


				December 31, 2025							December 31, 2024
	Fair Value Hierarchy Level	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value		Fair Value
Corporate notes and bonds	2	$	59,769	$	28	$	(12	)	$	59,785	$	109,711
Corporate commercial paper	2		156,713		32		(31	)		156,714		119,542
Available-for-sale investments			216,482		60		(43	)		216,499		229,253
Money market funds	1									11,919		15,993
Certificates of deposit	2									14,138		14,027
Cash	N/A									3,196		9,822
Total cash and investments in marketable securities									$	245,752	$	269,095

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2025

Income Tax Disclosure [Abstract]

Schedule of Income Before Income Tax, Domestic and Foreign

Loss before benefit for income taxes includes the following components (in thousands):


	Year Ended December 31,
	2025			2024
Domestic	$	(164,576	)	$	(119,227	)
Foreign		362			27
Loss before benefit for income taxes	$	(164,214	)	$	(119,200	)

Schedule of Benefit for Income Taxes

The benefit for income taxes consists of the following (in thousands):


	Year Ended December 31,
	2025			2024
Current:
Federal	$	—		$	—
State		8			(277	)
Foreign		(210	)		48
Total current income tax benefit		(202	)		(229	)
Deferred:
Federal		—			—
State		—			—
Foreign		64			(10	)
Total deferred income tax expense		64			(10	)
Benefit for income taxes	$	(138	)	$	(239	)

Schedule of Reconciliation of our U.S. Federal Statutory Tax Amount and Rate to Effective Amount and Rate

The following table presents the reconciliation of our U.S. federal statutory tax amount and rate to our effective amount and rate for the year ended December 31, 2025 (dollars in thousands):


	Year Ended December 31, 2025
	Amount			Percent
U.S. Federal Statutory Tax Rate	$	(34,485	)		21.0	%
State & local income taxes, net of federal income tax effect		8			0.0	%
Foreign tax effects		(295	)		0.2	%
Effects of changes in tax laws or rates enacted in the current period		—			0.0	%
Effects of cross-border tax laws		—			0.0	%
Research credits		(781	)		0.5	%
Changes in valuation allowances		6,913			(4.2	)%
Nontaxable or nondeductible items
Stock-based compensation		6,881			(4.2	)%
Liabilities related to the sales of future royalties, net		(4,085	)		2.5	%
Other		1,266			(0.8	)%
Changes in unrecognized tax benefits		(431	)		0.3	%
Other adjustments
Expiration of net operating loss carryforwards		24,806			(15.2	)%
Other		65			0.0	%
Benefit for income taxes	$	(138	)		0.1	%

The following table presents the required disclosures before our adoption of ASU 2023-09 and reconciles the U.S. federal statutory income tax rate to the actual global effective income tax rate for the year ended December 31, 2024 (in thousands):


	Year Ended December 31,
	2024
Income tax benefit at federal statutory rate	$	(25,032	)
Research credits		7,741
Change in valuation allowance		1,635
Expiration of net operating loss carryforwards		8,252
Stock-based compensation		4,280
Non-cash interest expense on liabilities related to sales of future royalties		5,904
Non-cash royalty revenue related to sales of future royalties		(5,645	)
Impairment of goodwill		—
Other		2,626
Benefit for income taxes	$	(239	)

Effective Tax Rate		0.20	%

Schedule of Significant Components of Deferred Tax Assets and Liabilities

We measure deferred tax assets and liabilities based on the rates at which they are expected to reverse in the future. Significant components of our deferred tax assets for federal and state income taxes are as follows (in thousands):


	December 31,
	2025			2024
Deferred tax assets:
Net operating loss carryforwards	$	625,497		$	587,528
Research and other credits		137,530			135,871
Net capital loss carryforwards		39,648			39,648
Operating lease liabilities		24,517			22,767
Stock-based compensation		18,277			19,619
Capitalized research and development costs		35,183			45,607
Liabilities related to the sales of future royalties		—			2,020
Other		12,830			9,402
Deferred tax assets before valuation allowance		893,482			862,462
Valuation allowance for deferred tax assets		(892,432	)		(859,084	)
Total deferred tax assets		1,050			3,378
Deferred tax liabilities:
Investment in foreign subsidiary		(575	)		(511	)
Other		(1,050	)		(3,377	)
Total deferred tax liabilities		(1,625	)		(3,888	)
Net deferred tax assets (liabilities)	$	(575	)	$	(510	)

Schedule of Unrecognized Tax Benefits

We have the following activity relating to unrecognized tax benefits (in thousands):


	Year Ended December 31,
	2025			2024
Beginning balance	$	135,672		$	126,498
Tax positions related to current year:
Additions		704			582
Reductions		—			—
Tax positions related to prior years:
Additions		27			10,101
Reductions		(9	)		(16	)
Settlements		—			(815	)
Lapses in statute of limitations		(459	)		(678	)
Ending balance	$	135,935		$	135,672

Cash and Investments in Marketable Securities - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2025 USD ($) Investments	Dec. 31, 2024 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Target maturity period	2 years
Weighted average maturity period	1 year
Sales of investments	$ 0	$ 0
Accrued interest receivable	$ 600	1,100
Number of investments in unrealized loss positions \| Investments	19
Investments in continuous unrealized loss positions for 12 months or longer	$ 0
Letter of credit	$ 7,800	$ 7,500

Subsequent Events

12 Months Ended

Dec. 31, 2025

Subsequent Events [Abstract]

Subsequent Events

Note 15 — Subsequent Events

From February 20, 2026 through March 11, 2026, we issued 639,131 shares of our common stock under the November 2025 ATM Sales Agreement at a weighted average price of $71.15 per share for net proceeds of $44.1 million after deducting related commissions of approximately $1.4 million.

Restructuring and Impairment - Summary of Restructuring Plans, Restructuring and Impairment (Details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2025

Dec. 31, 2024

Restructuring Cost and Reserve [Line Items]

Impairment of right-of-use assets and property, plant and equipment

$ 4,441

$ 8,329

Restructuring and impairment

9,331

15,670

^[1]

2022 and 2023 Restructuring Plans

Restructuring Cost and Reserve [Line Items]

Impairment of right-of-use assets and property, plant and equipment

4,441

8,329

Contract termination costs

4,890

7,341

Restructuring and impairment

$ 9,331

$ 15,670

[1]	All share and per share amounts have been retrospectively adjusted to reflect a one-for-fifteen reverse stock split (see Note 8).

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Restructuring and Related Activities [Abstract]

Gain on Sale of the Huntsville Manufacturing Facility - Summary of Gain Computation (Details) - USD ($) $ in Thousands		12 Months Ended
	Dec. 02, 2024	Dec. 31, 2025	Dec. 31, 2024
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on asset sale		$ 0	$ 40,390
Huntsville Manufacturing Facility
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash proceeds at closing	$ 71,167
Net working capital adjustment	(322)
Fair value of equity method investment in Gannet BioChem - Level 3 of Fair Value Hierarchy	12,218
Gross cash and non-cash proceeds	83,063
Transaction costs	(6,155)
Net proceeds	76,908
Accounts receivable	4,250
Inventory	14,655
Other current assets	864
Current liabilities	(1,354)
Net working capital	18,415
Property, plant and equipment, net	11,569
Contract asset, net	6,534
Net assets sold	36,518
Net assets sold	(36,518)
Gain on asset sale	$ 40,390

Restructuring and Impairment

12 Months Ended

Dec. 31, 2025

Restructuring and Impairment

Note 10 — Restructuring and Impairment

As discussed in Note 1, in April 2022 and April 2023, we announced the 2022 Restructuring Plan and the 2023 Restructuring Plan, pursuant to which we terminated significant portions of our workforce and decided to sublease all of our leased premises in San Francisco, California, including our office leased space in the Third Street Facility and our office and laboratory space in the Mission Bay Facility.

In connection with our 2022 and 2023 Restructuring Plans, restructuring and impairment includes the following (in thousands):


	Year ended December 31,
	2025		2024
Impairment of right-of-use assets and property, plant and equipment	$	4,441	$	8,329
Contract termination costs		4,890		7,341
Restructuring and impairment	$	9,331	$	15,670

Impairment of Long-Lived Assets

As a result of our 2022 and 2023 Restructuring Plans, we decided to seek a sublease for all of our leased spaces in the Third St. Facility and the Mission Bay Facility. Accordingly, we evaluate each space for impairment at each reporting date, as facts and circumstances change. The significant assumptions in our impairment analysis relate to sublease income, including the length of time to enter into a sublease, sublease rental payments, free rent periods, tenant improvement allowances and broker commissions. When available, we use sublease negotiations or agreements, but in the absence of such information, we develop our own subjective estimates based on current real estate trends and market conditions. Accordingly, our estimates are subject to significant risk, and the terms of sublease agreements, if any, and the resulting amount and timing of sublease income, if ever realized, may be materially different than our estimates.

As part of our evaluation of each sublease space, we separately compare the estimated undiscounted sublease income, if any, as described above, for each sublease to the net book value of the related long-term assets, which include right-of-use assets and certain property, plant and equipment, primarily for leasehold improvements (collectively, sublease assets). If such sublease income exceeds the net book value of the sublease assets, we do not record an impairment charge. Otherwise, we

record an impairment charge by reducing the net book value of the sublease assets to their estimated fair value, which we determined by discounting the estimated sublease income using the estimated borrowing rate of a market participant subtenant, which we estimated to be 6.2% for the three months ended June 30, 2024.

During the year ended December 31, 2024, as the life sciences and office lease markets continued to deteriorate, we recorded non-cash impairment charges totaling $8.3 million, consisting of $3.9 million for our office and laboratory leased space in the Mission Bay Facility and $4.4 million for our office lease space in the Third St. Facility.

We recorded an additional $4.4 million non-cash impairment charges for our office and laboratory leased space in the Mission Bay Facility during the three month ended December 31, 2025 as the life sciences and office lease markets continued to demonstrate a sustained weakness.

For these impairment charges, we developed our estimates of sublease income based on market participant assumptions as described above.

The following is a reconciliation of the impairment charges we recorded for the full years ended December 31, 2025 and 2024, including the net book values of the sublease assets before the impairment and the fair values of the sublease assets (in thousands):


	Year-Ended December 31, 2025
	Operating Lease Right-of-Use Assets		Property, Plant and Equipment		Total
Net book value of impaired sublease assets	$	3,817	$	624	$	4,441
Less: Fair value of impaired facilities — Level 3 of Fair Value Hierarchy		—		—		—
Total impairment of right-of-use assets and property, plant and equipment	$	3,817	$	624	$	4,441


	Year Ended December 31, 2024
	Operating Lease Right-of-Use Assets			Property, Plant and Equipment			Total
Net book value of impaired sublease assets	$	12,506		$	1,897		$	14,403
Less: Fair value of impaired sublease assets — Level 3 of Fair Value Hierarchy		(5,219	)		(855	)		(6,074	)
Total impairment of right-of-use assets and property, plant and equipment	$	7,287		$	1,042		$	8,329

Contract Termination Costs

We have incurred significant contract termination costs in connection with our Restructuring Plans. Because we continue to adjust the liability based on updates to our assumptions at each reporting date, we continue to recognize expense as our estimates change until settlement.

The following are reconciliations of the contract termination costs, for the years ended December 31, 2025 and 2024 (in thousands):


	Year Ended December 31,
Liability balances as of December 31, 2023	$	5,542
Expense recognized during the period		7,341
Payments during the period		(3,805	)
Liability balances as of December 31, 2024		9,078
Expense recognized during the period		4,890
Payments during the period		(3,286	)
Liability balances as of December 31, 2025	$	10,682

As of December 31, 2025 and 2024, we reported $2.6 million and $2.8 million, respectively, within accrued expenses and remaining amounts within other long-term liabilities on our Consolidated Balance Sheets.

Gain on Sale of the Huntsville Manufacturing Facility (Tables)

12 Months Ended

Dec. 31, 2025

Discontinued Operations and Disposal Groups [Abstract]

Summary of Gain Computation

The gain was computed as follows (in thousands):


Cash proceeds at closing	$	71,167
Net working capital adjustment		(322	)
Fair value of equity method investment in Gannet BioChem - Level 3 of Fair Value Hierarchy		12,218
Gross cash and non-cash proceeds		83,063
Transaction costs		(6,155	)
Net proceeds	$	76,908


Accounts receivable	$	4,250
Inventory		14,655
Other current assets		864
Current liabilities		(1,354	)
Net working capital		18,415
Property, plant and equipment, net		11,569
Contract asset, net		6,534
Net assets sold	$	36,518


Net proceeds	$	76,908
Net assets sold		(36,518	)
Gain on asset sale	$	40,390

Schedule of Assumptions Used to Calculate the Fair Value of the Equity Method Investment

The following table lists the other Black-Scholes option-pricing model assumptions used to calculate the fair value of the equity method investment.


Risk-free interest rate	4.1	%
Dividend yield	0.0	%
Volatility factor	50.0	%

Tabular disclosure of information related to a disposal group. Includes, but is not limited to, a discontinued operation, disposal classified as held-for-sale or disposed of by means other than sale or disposal of an individually significant component.

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Restructuring and Impairment - Restructuring Reserve Rollforward (Details) - Contract Termination and Other Costs - Restructuring Plan - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	$ 9,078	$ 5,542
Expense recognized during the period	$ 4,890	$ 7,341
Restructuring Charges, Statement of Income or Comprehensive Income [Extensible Enumeration]	Restructuring Costs and Asset Impairment Charges	Restructuring Costs and Asset Impairment Charges
Payments during the period	$ (3,286)	$ (3,805)
Restructuring reserve, ending balance	$ 10,682	$ 9,078

Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

Schedule of Equity Method Investments [Line Items]

Equity Method Investment - Additional Information (Details) - USD ($)
$ / shares in Units, shares in Millions

12 Months Ended

Dec. 02, 2024

Dec. 31, 2025

Dec. 31, 2024

^[1]

Equity method investment dividends or distributions

$ 20,000,000

Equity method investment dividends or distributions per unit

$ 1

Research and development expenses

$ 117,330,000

$ 120,908,000

Huntsville Manufacturing Facility

$ 361,000

$ (390,000)

Schedule of Equity Method Investments [Line Items]

Common unit, price per unit

$ 1

Percentage of the common units outstanding

100.00%

Huntsville Manufacturing Facility | Stock Appreciation Rights (SARs)

Schedule of Equity Method Investments [Line Items]

Shares issued

8.4

Shares reserved for issuance

11.3

Gannet BioChem

Schedule of Equity Method Investments [Line Items]

Minimum purchase commitments

$ 0

Gannet BioChem | Huntsville Manufacturing Facility

Schedule of Equity Method Investments [Line Items]

Common units owned

20.0

Services Agreements | Gannet BioChem

Schedule of Equity Method Investments [Line Items]

Agreement term

2 years

Research and development expenses

$ 1,900,000

Supply Agreements | Gannet BioChem

1,100,000

Net accounts receivable

400,000

Net payable

1,100,000

Schedule of Equity Method Investments [Line Items]

Research and development expenses

$ 700,000

Asset Acquisition By Ampersand Capital Partners | Huntsville Manufacturing Facility

Schedule of Equity Method Investments [Line Items]

Preferred units owned by a related party

81.5

Preferred unit, price per unit owned by related party

$ 1

Percentage of the preferred units owned by related party outstanding

100.00%

Percentage of preferred units outstanding

99.70%

Asset Acquisition By Ampersand Capital Partners | Huntsville Manufacturing Facility | Stock Appreciation Rights (SARs)

Schedule of Equity Method Investments [Line Items]

Share issued base value

$ 1

Asset Acquisition By Ampersand Capital Partners | Asset Purchase Agreement | Huntsville Manufacturing Facility

Schedule of Equity Method Investments [Line Items]

Consideration in cash, net of transaction costs

$ 64,700,000

[1]	All share and per share amounts have been retrospectively adjusted to reflect a one-for-fifteen reverse stock split (see Note 8).

Consolidated Financial Statement Details

12 Months Ended

Dec. 31, 2025

Inventory Disclosure [Abstract]

Consolidated Financial Statement Details

Note 3 — Consolidated Financial Statement Details

Other Current Assets

Other current assets consists of the following (in thousands):


	December 31,
	2025		2024
Prepaid research and development expenses	$	16,540	$	1,947
Interest and other non-trade receivables		1,779		1,609
Other prepaid expenses		2,195		2,510
Total other current assets	$	20,514	$	6,066

Accrued Expenses

Accrued expenses consist of the following (in thousands):


	December 31,
	2025		2024
Accrued research and development expenses	$	13,980	$	14,453
Accrued compensation		2,940		2,832
Accrued contract termination costs		2,632		2,767
Other accrued expenses		2,719		9,920
Total accrued expenses	$	22,271	$	29,972

Organization and Summary of Significant Accounting Policies - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Stock Options, RSUs And PSUs
Organization And Summary Of Significant Accounting Policies [Line Items]
Potentially dilutive securities (in shares)	2,260,593	1,788,719

Stockholders' Equity - Schedule of Shares of Common Stock Reserved for Future Issuance (Details) - shares	Dec. 31, 2025	Dec. 31, 2024
Class of Stock [Line Items]
Total common stock reserved for issuance	3,300,607	4,571,228
2017 Performance Incentive Plan
Class of Stock [Line Items]
Total common stock reserved for issuance	353,240	551,727
2025 Inducement Plan
Class of Stock [Line Items]
Total common stock reserved for issuance	231,690	0
Employee Stock Purchase Plan
Class of Stock [Line Items]
Total common stock reserved for issuance	45,858	47,383
TCG Crossover Fund II, L.P. \| Pre-Funded Warrant
Class of Stock [Line Items]
Total common stock reserved for issuance	0	1,666,667
Stock Options and RSUs Outstanding
Class of Stock [Line Items]
Total common stock reserved for issuance	2,669,819	2,305,451

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Less: portion representing interest

Operating Leases - Schedule of Future Minimum Lease Payments for Operating Leases (Details) - USD ($)
$ in Thousands

Dec. 31, 2025

Dec. 31, 2024

^[1]

Leases [Abstract]

$ 21,096

23,682

24,427

25,195

2,108

96,508

(10,757)

Operating lease liabilities

85,751

Less: current portion

(20,495)

$ (19,868)

Operating lease liabilities, less current portion

$ 65,256

$ 82,696

[1]	All share and per share amounts have been retrospectively adjusted to reflect a one-for-fifteen reverse stock split (see Note 8).

Commitments and Contingencies - Additional Information (Details) - USD ($)	Dec. 31, 2025	Dec. 31, 2024
Loss Contingencies [Line Items]
Purchase commitments related to contract manufacturing, clinical development and certain other items	$ 3,700,000
Repayment due of GST refunds	3,300,000
Liability for litigation	0	$ 0
Indemnification Obligation
Loss Contingencies [Line Items]
Litigation matters, liabilities	0	$ 0
Merger and Acquisition Related Claims \| Maximum
Loss Contingencies [Line Items]
Obligations under Director and Officer Indemnifications per incident	2,500,000
Securities Related Claims
Loss Contingencies [Line Items]
Obligations under Director and Officer Indemnifications per incident	2,500,000
Non-Securities Related Claims
Loss Contingencies [Line Items]
Obligations under Director and Officer Indemnifications per incident	$ 2,500,000

Operating Leases - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2025 USD ($) ft² Option	Dec. 31, 2024 USD ($)
Leases [Line Items]
Operating lease, payments \| $	$ 22.3	$ 21.6
Weighted average remaining lease term	4 years 1 month 6 days
Weighted average discount rate, percent	5.80%
General and Administrative Expense
Leases [Line Items]
Total sublease income \| $	$ 3.7	3.2
Sublease Property, Plant And Equipment
Leases [Line Items]
Impairment of right-of-use assets and property, plant and equipment \| $	$ 3.8	$ 7.3
Mission Bay Facility
Leases [Line Items]
Lease space (in sq ft) \| ft²	155,215
Subleases space (in sq ft) \| ft²	29,000
Number of renewal options \| Option	2
Renewal term (in years)	5 years
Third Street Facility
Leases [Line Items]
Lease space (in sq ft) \| ft²	135,936
Number of renewal options \| Option	1
Renewal term (in years)	5 years

Cash and Investments in Marketable Securities

12 Months Ended

Dec. 31, 2025

Fair Value Disclosures [Abstract]

Cash and Investments in Marketable Securities

Note 2 — Cash and Investments in Marketable Securities

Cash and investments in marketable securities, including cash equivalents, are as follows (in thousands):


	Estimated Fair Value at
	December 31,		December 31,
	2025		2024
Cash and cash equivalents	$	15,116	$	44,252
Short-term investments		230,636		210,974
Long-term investments		—		13,869
Total cash and investments in marketable securities	$	245,752	$	269,095

We invest in liquid, high quality debt securities. Our investments in debt securities are subject to interest rate risk. To minimize the exposure due to an adverse shift in interest rates, we invest in securities with maturities of two years or less and maintain a weighted average maturity of one year or less. We currently do not intend to sell these securities prior to maturity and it is more likely than not that we will not be required to sell these securities before we recover the amortized cost basis.

During the years ended December 31, 2025 and 2024, we did not sell any available-for-sale securities.

We report our accrued interest receivable, which totaled $0.6 million and $1.1 million at December 31, 2025 and 2024, respectively, in other current assets on our Consolidated Balance Sheets.

Our portfolio of cash and investments in marketable securities includes (in thousands):


				December 31, 2025							December 31, 2024
	Fair Value Hierarchy Level	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value		Fair Value
Corporate notes and bonds	2	$	59,769	$	28	$	(12	)	$	59,785	$	109,711
Corporate commercial paper	2		156,713		32		(31	)		156,714		119,542
Available-for-sale investments			216,482		60		(43	)		216,499		229,253
Money market funds	1									11,919		15,993
Certificates of deposit	2									14,138		14,027
Cash	N/A									3,196		9,822
Total cash and investments in marketable securities									$	245,752	$	269,095

At December 31, 2024, our gross unrealized gains and losses were insignificant. As of December 31, 2025 and 2024, we assessed our marketable securities with unrealized losses and concluded that the losses were not attributable to credit. For the twelve months ended December 31, 2025 and 2024, there were no transfers between Level 1 and Level 2 of the fair value hierarchy. As of December 31, 2025, we had 19 investments in unrealized loss positions and no investments had been in continuous unrealized loss positions for 12 months or longer. Accordingly, we have not recorded an allowance for credit losses for these securities.

At both December 31, 2025 and 2024, we had letter of credit arrangements in favor of our landlords and certain vendors totaling $7.8 million and $7.5 million, respectively. These letters of credit are secured by investments of similar amounts.

Cover - USD ($) $ in Millions	12 Months Ended
Cover - USD ($) $ in Millions	Dec. 31, 2025	Mar. 11, 2026	Jun. 30, 2025
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2025
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	0-24006
Entity Registrant Name	NEKTAR THERAPEUTICS
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	94-3134940
Entity Address, Address Line One	455 Mission Bay Boulevard South
Entity Address, City or Town	San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94158
City Area Code	415
Local Phone Number	482-5300
Title of 12(b) Security	Common Stock, $0.0001 par value
Trading Symbol	NKTR
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction Flag	false
Entity Shell Company	false
Entity Public Float			$ 318
Entity Common Stock, Shares Outstanding (in shares)		28,687,963
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Portions of registrant’s definitive Proxy Statement to be filed for its 2026 Annual Meeting of Stockholders are incorporated by reference into Part III hereof. Such Proxy Statement will be filed with the Securities and Exchange Commission within 120 days of the end of the fiscal year covered by this Annual Report on Form 10-K.
Amendment Flag	false
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	FY
Entity Central Index Key	0000906709
Auditor Name	Ernst & Young LLP
Auditor Location	San Mateo, California
Auditor Firm ID	42
Auditor Opinion [Text Block]	Opinion on the Financial Statements We have audited the accompanying consolidated balance sheets of Nektar Therapeutics (the Company) as of December 31, 2025 and 2024, the related consolidated statements of operations, comprehensive loss, stockholders’ equity and cash flows for each of the two years in the period ended December 31, 2025, and the related notes (collectively referred to as the “consolidated financial statements”). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company at December 31, 2025 and 2024, and the results of its operations and its cash flows for each of the two years in the period ended December 31, 2025, in conformity with U.S. generally accepted accounting principles.

Consolidated Financial Statement Details - Schedule of Accrued Expenses (Details) - USD ($)
$ in Thousands

Dec. 31, 2025

Dec. 31, 2024

Inventory Disclosure [Abstract]

Accrued research and development expenses

$ 13,980

$ 14,453

Accrued compensation

2,940

2,832

Accrued contract termination costs

2,632

2,767

Other accrued expenses

2,719

9,920

Total accrued expenses

$ 22,271

$ 29,972

^[1]

[1]	All share and per share amounts have been retrospectively adjusted to reflect a one-for-fifteen reverse stock split (see Note 8).

Operating Leases

12 Months Ended

Dec. 31, 2025

Leases [Abstract]

Operating Leases

Note 5 — Operating Leases

Our leases consist of a Lease Agreement (the Mission Bay Lease) with ARE-San Francisco No. 19, LLC (ARE) for our 155,215 square foot corporate office and R&D facility located at 455 Mission Bay Boulevard South, San Francisco, California (the Mission Bay Facility) and a Lease Agreement (the Third Street Lease) with Kilroy Realty Finance Partnership, L.P. (Kilroy) for an additional 135,936 square foot of office space at 360 Third Street, San Francisco, California (the Third Street Facility). Both leases terminate on January 31, 2030, subject to two consecutive five year renewal options for the Mission Bay Facility and one five year renewal option for the Third Street Facility. Other key terms include the following:

•

The monthly base rent for both facilities will escalate over the term of the lease at various intervals.

•

Both leases include various covenants, indemnities, defaults, termination rights, letters of credit and other provisions customary for lease transactions of this nature.

•

During the term of the Mission Bay Lease, we are responsible for paying our share of operating expenses specified in the lease, including utilities, common area maintenance, insurance costs and taxes.

•

For the Third Street Lease, our fixed annual base rent on an industrial gross lease basis includes certain expenses and property taxes paid directly by the landlord.

Due to our 2022 and 2023 Restructuring Plans, during the years ended December 31, 2025 and 2024, we recorded impairment charges of $3.8 million and $7.3 million, respectively, for our right-of-use assets which we are seeking to sublease. See Note 10 for additional information.

We generally recognize lease expense for our operating leases on a straight-line basis over the lease term. For spaces where we have recognized an impairment charge, the aggregate lease expense recognized over the remaining term is reduced by the amount of the impairment charge, but we recognize the remaining lease expense on an accelerated basis. The components of lease expense, which we include in general and administrative expense in our Consolidated Statements of Operations, were as follows (in thousands):


	Year Ended December 31,
	2025		2024
Operating lease expense	$	7,155	$	8,723
Variable lease expense		7,905		9,000
Total lease expense	$	15,060	$	17,723

During the years ended December 31, 2025 and 2024, we paid $22.3 million and $21.6 million, respectively, of operating lease payments related to our lease liabilities, which we include in net cash used in operating activities in our Consolidated Statements of Cash Flows.

As of December 31, 2025, the maturities of our operating lease liabilities were as follows (in thousands):


Year ending December 31,
2026	$	21,096
2027		23,682
2028		24,427
2029		25,195
2030 and thereafter		2,108
Total lease payments		96,508
Less: portion representing interest		(10,757	)
Operating lease liabilities		85,751
Less: current portion		(20,495	)
Operating lease liabilities, less current portion	$	65,256

As of December 31, 2025, the weighted-average remaining lease term is 4.1 years and the weighted-average discount rate was 5.8%.

We have entered into subleases for approximately 29,000 square feet of space in our Mission Bay Facility that provide for fixed lease payments, as well as full recovery of the subtenants’ share of operating expenses under our master lease agreement, subject to certain free rent periods. We record the total sublease income as a reduction of general and administrative expense, which totaled $3.7 million and $3.2 million for the years ended December 31, 2025 and 2024, respectively.

As of December 31, 2025, maturities of our operating lease receivables from subleases for each of the next five years and thereafter were as follows:


Year ending December 31,
2026	$	1,670
2027		1,729
2028		1,788
2029		1,846
2030 and thereafter		—
Gross lease receivable	$	7,033

Segment Reporting - Revenue by Geographic Area (Detail) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2025

Dec. 31, 2024

Revenue by geographic area

United States | Reportable Geographical Components

$ 55,232

$ 98,427

^[1]

Revenue by geographic area

Rest of World | Reportable Geographical Components

1,375

Revenue by geographic area

$ 55,232

$ 97,052

[1]	All share and per share amounts have been retrospectively adjusted to reflect a one-for-fifteen reverse stock split (see Note 8).

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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Schedule of Equity Method Investments [Line Items]

Equity Method Investment - Schedule of equity method investment (Details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2025

Dec. 31, 2024

Change in claim on net assets of Gannet BioChem

$ (8,727)

$ 0

^[1]

Gannet BioChem

Schedule of Equity Method Investments [Line Items]

Claim on net assets of Gannet BioChem - beginning of period

12,218

Claim on net assets of Gannet BioChem - end of period

3,491

$ 12,218

Change in claim on net assets of Gannet BioChem

$ (8,727)

[1]	All share and per share amounts have been retrospectively adjusted to reflect a one-for-fifteen reverse stock split (see Note 8).

Amount of income (loss) for proportionate share of equity method investee's income (loss).

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

License And Collaboration Agreements [Abstract]

License and Collaboration Agreements

12 Months Ended

Dec. 31, 2025

License and Collaboration Agreements

Note 9 — License and Collaboration Agreements

We have entered into various collaboration agreements including license agreements and collaborative research, development and commercialization agreements with various pharmaceutical and biotechnology companies. Under these collaboration arrangements, we are entitled to receive license fees, upfront payments, milestone and other contingent payments, royalties, sales milestone payments, reimbursements for research and development activities and (before the sale of the Facility) payments for the manufacture and supply of our PEG reagents. We generally include our costs of performing these services in research and development expense, except for costs for product sales to our collaboration partners which we include in cost of goods sold. We analyze our agreements to determine whether we should account for the agreements within the scope of ASC 808 Collaborative Arrangements, and, if so, we analyze whether we should account for any elements under ASC 606 Revenue from Contracts with Customers.

Biolojic Design, Ltd. (Biolojic): NKTR-0165

In 2021, we entered into a research collaboration and license option agreement with Biolojic to discover and develop agonistic antibodies that activate a novel and previously un-drugged target for the treatment of autoimmune diseases. In 2023, we exercised an option to gain an exclusive license to specified agonistic antibodies and other materials that were developed pursuant to this arrangement in all fields of use (other than in the field of oncology). As a result of exercising the option to gain an exclusive license, we may be required to pay up to $18.0 million based on the achievement of certain development milestones, including the first milestone of $3.0 million payable upon the acceptance of the first investigational new drug application, and up to $35.0 million based on the achievement of certain regulatory approval milestones. Each milestone is payable only once, regardless of the number of indications for which we develop the licensed product. We record a liability when a milestone payment becomes probable. As of December 31, 2025, no milestones have been achieved or are considered probable, and no liability has been recorded.

Bristol-Myers Squibb Company (BMS): Bempegaldesleukin, also referred to as NKTR-214

Effective April 3, 2018, we entered into a Strategic Collaboration Agreement (the BMS Collaboration Agreement) and a Share Purchase Agreement with BMS. Pursuant to the BMS Collaboration Agreement, we and BMS jointly developed bempegaldesleukin in combination with BMS’ Opdivo®. Upon the effective date of these agreements, BMS paid us a non-refundable upfront cash payment of $1.0 billion and purchased 552,307 shares of our common stock for total additional cash consideration of $850.0 million.

In April 2022, we announced that BMS and we decided to discontinue all development of bempegaldesleukin in combination with Opdivo®. On September 6, 2023, BMS and we terminated the BMS Collaboration Agreement. On February 12, 2024, we repurchased the 552,307 shares previously sold to BMS for total cash consideration of $3.0 million.

Other

We have other collaboration agreements that have resulted in commercialized products for our collaborations partners. Under these agreements, we are entitled to receive royalties based on net sales of these products as well as sales milestones. As discussed in Note 6, we have sold our rights to receive royalties from these other collaboration agreements.

We have a collaboration agreement with UCB for dapirolizumab pegol, under which we are entitled to a total of up to $40.0 million of regulatory approval milestones, as well as royalties in the low single digits based on net sales of commercialized products, if any. UCB is developing dapirolizumab pegol, a PEGylated antibody fragment, with Biogen, Inc. for the treatment of systemic lupus erythematosus. However, given the current phase of development of this product and the uncertainty in clinical development, we have excluded these milestones from the transaction price for this agreement.

On July 31, 2024, and further formalized in an Amended and Restated Manufacturing and Supply Agreement dated October 18, 2024, we entered into a long-term “take or pay” supply agreement with UCB that increases the selling price of the PEG reagent used in the manufacture of CIMZIA® (the UCB Supply Agreement). The UCB Supply Agreement also covers UCB’s purchases of the same reagent (at the same price) for use in the manufacture of dapirolizumab pegol. We analyzed the terms of the agreement, including its cancellation provisions, and concluded that it represents a long-term agreement. Since the performance obligations are deliveries of a single reagent, we determined a single sales price for recognition of revenue over the term of the arrangement. Accordingly, because the billed price was less than the single sales price, we recorded a contract asset of $7.0 million as of December 2, 2024. Pursuant to the APA between Gannet BioChem and us, the UCB Supply Agreement was assigned to Gannet BioChem upon closing of the sale of the Facility.

We have not sold our rights to receive these milestones or royalties from dapirolizumab pegol under the APA for the sale of the Facility, and the assignment of the supply agreements to Gannet BioChem does not alter the potential milestones and potential royalties payable by UCB to us pursuant to the collaboration agreement for dapirolizumab pegol nor the non-cash royalties payable under our collaboration agreement for CIMZIA®. See Note 4 for additional information on the APA.

Segment Reporting (Tables)

12 Months Ended

Dec. 31, 2025

Segment Reporting [Abstract]

Summary of Significant Expense Categories and Consolidated Net Loss

The following is a summary of the significant expense categories and consolidated net loss details provided to the CODM (in thousands):


	Year Ended December 31,
	2025			2024
Revenue:	$	55,232		$	98,427
Operating costs and expenses:
Cost of goods sold		—			30,686
Clinical development, contract manufacturing and other third party costs
Rezpegaldesleukin (IL-2 receptor agonist/regulatory T cell agent)		51,531			49,382
NKTR-255 (IL-15 receptor agonist)		6,486			15,795
NKTR-0165 (tumor necrosis factor receptor type II agonist)		9,569			9,339
Discovery research and other programs		1,833			2,334
Total clinical development, contract manufacturing and other third party costs		69,419			76,850
Employee costs (a)(b)		46,003			40,204
Facilities costs (a)		12,306			16,821
Other operating costs (a)(c)		44,727			42,047
Other segment expenses		22,879			37,407
Gain on sale of the Huntsville manufacturing facility		—			(40,390	)
Total operating costs and expenses		195,334			203,625
Loss from operations		(140,102	)		(105,198	)
Non-operating income (expense):
Non-cash interest expense on liabilities related to sales of future royalties		(26,184	)		(28,112	)
Interest income		10,438			14,500
Other income (expense), net		361			(390	)
Total non-operating income (expense), net		(15,385	)		(14,002	)
Loss before benefit for income taxes and equity method investment		(155,487	)		(119,200	)
Benefit for income taxes		(138	)		(239	)
Loss before equity method investment		(155,349	)		(118,961	)
Loss from equity method investment		(8,727	)		—
Net loss	$	(164,076	)	$	(118,961	)

Schedule of Other Segment Expense Items Included within Net Loss

Other segment expense items included within net loss include the following (in thousands):


	Year Ended December 31,
	2025		2024
Impairment of right-of-use assets and property, plant and equipment	$	4,441	$	8,329
Contract termination costs		4,890		7,341
Stock-based compensation (a)		12,649		19,666
Depreciation and amortization expense (a)		899		2,071
Total other segment expenses	$	22,879	$	37,407

Employee costs, facilities costs, other operating costs, stock-based compensation expense and depreciation and amortization expense include amounts reported in research and development expense and general and administrative expense in our Consolidated Statements of Operations. Such amounts reported in cost of goods sold in our Consolidated Statements of Operations are included in cost of goods sold in the summary of significant segment expenses above.

Includes compensation and benefits for our employees and costs for our contractors and temporary workers.

Includes legal and patent expenses, information technology infrastructure and other costs, professional accounting, insurance, travel and entertainment and other third-party services and expenses.

Schedule of Revenue by Geographic Area

Revenue by geographic area is based on the headquarters or shipping locations of our partners. The following table sets forth revenue by geographic area (in thousands):


	Year Ended December 31,
	2025		2024
United States	$	—	$	1,375
Rest of World		55,232		97,052
Total revenue	$	55,232	$	98,427

Cash and Investments in Marketable Securities - Cash and Investments in Marketable Securities, Including Cash Equivalents (Details) - USD ($)
$ in Thousands

Dec. 31, 2025

Dec. 31, 2024

Estimated Fair Value at

Cash and cash equivalents

$ 15,116

$ 44,252

^[1]

Short-term investments

230,636

210,974

^[1]

Long-term investments

13,869

^[1]

Total cash and investments in marketable securities

$ 245,752

$ 269,095

[1]	All share and per share amounts have been retrospectively adjusted to reflect a one-for-fifteen reverse stock split (see Note 8).

Liabilities Related to the Sales of Future Royalties

12 Months Ended

Dec. 31, 2025

Note 6 — Liabilities Related to the Sales of Future Royalties

On February 24, 2012, for gross proceeds of $124.0 million, we entered into a purchase and sale agreement (the 2012 Purchase and Sale Agreement) with RPI Finance Trust (RPI), an affiliate of Royalty Pharma, pursuant to which we sold, and RPI purchased, our right to receive royalty payments (the 2012 Transaction Royalties) arising from the worldwide net sales, from and after January 1, 2012, of (a) CIMZIA®, under our license, manufacturing and supply agreement with UCB Pharma (UCB), and (b) MIRCERA®, under our license, manufacturing and supply agreement with F. Hoffmann-La Roche Ltd and Hoffmann-La Roche Inc. (together referred to as Roche). As a result of our ongoing manufacturing and supply obligations related to the generation of these royalties, we recorded the proceeds as debt, and we recognize non-cash royalty revenue, as

royalties from the CIMZIA® and MIRCERA® products are remitted directly to RPI, and non-cash interest expense to amortize the liability using the effective interest method over the estimated life of the 2012 Purchase and Sale Agreement.

We were required to pay RPI an aggregate $10.0 million as a result of worldwide net sales of MIRCERA® during the years 2013 and 2012 not reaching certain minimum thresholds. The 2012 Purchase and Sale Agreement does not include any other potential payments related to minimum net sales thresholds.

On June 5, 2020, UCB served notice of a Declaratory Judgment of Patent Invalidity, filed in the United States District Court for the District of Delaware, seeking a declaration of invalidity of certain of our patents that we had licensed to UCB and pursued similar actions in other jurisdictions. On October 14, 2021, RPI and we entered into a Letter Agreement which permitted us to enter into a Settlement Agreement, effective October 13, 2021, with UCB to effect the negotiation between RPI and UCB in which UCB and RPI agreed to a reduction in the royalty term and annual decreases in the royalty rate over the remaining royalty term in exchange for UCB’s withdrawal of all of UCB’s litigation and challenges.

We concluded that we should account for the decrease in royalty payments to RPI as a result of these agreements as a modification of our liability. Due to the significance of the change in the estimated royalty payments, we concluded that we should treat the modification as an extinguishment of the prior liability and recognize a new liability based on the revised royalty payments and term, discounted to fair value. Accordingly, we estimated the fair value to be approximately $84.7 million. As a result, we recognized a non-cash loss of $23.5 million on the revaluation of the prior liability in the three months ended December 31, 2021, and we wrote off the remaining $0.9 million of unamortized transaction costs.

On December 16, 2020, for gross proceeds of $150.0 million, we entered into a capped purchase and sale agreement (the 2020 Purchase and Sale Agreement) with entities managed by Healthcare Royalty Management, LLC (collectively, HCR). Pursuant to the 2020 Purchase and Sale Agreement, we agreed to sell to HCR certain of our rights to receive royalty payments arising from the worldwide net sales, from and after October 1, 2020, of (a) MOVANTIK® under our license agreement with AstraZeneca AB (Astra Zeneca), as amended, (b) ADYNOVATE® under our research, development, license and manufacturing and supply agreement with Baxalta US Inc. and Baxalta GmbH (collectively, Baxalta), as amended, (c) REBINYN® under our settlement and license agreement with Novo Nordisk Inc., Novo Nordisk A/S and Novo Nordisk A/G and (d) licensed products under that our right to sublicense agreement with Baxalta. As a result of the cap on the royalties to be received by HCR and our ongoing manufacturing and supply obligations related to the generation of these royalties, we recorded the proceeds as debt, and we recognize non-cash royalty revenue, as royalties from these products are remitted directly to HCR, and non-cash interest expense to amortize the liability using the effective interest method over the estimated life of the 2020 Purchase and Sale Agreement. As of December 31, 2025, our prospective effective interest rate used to amortize the liability is 49.2%.

The original 2020 Purchase and Sale Agreement was to expire -- and wherein the right to receive royalties would revert to us -- if HCR received aggregate royalties of $210.0 million on or prior to December 31, 2025 (the 2025 Threshold), or, if the 2025 Threshold was not achieved by December 31, 2025, when HCR received aggregate royalties of $240.0 million. On March 4, 2024, Nektar and HCR amended the original 2020 Purchase and Sale Agreement (the Amendment), pursuant to which the parties agreed to remove our reversionary rights in the royalties in exchange for a $15.0 million payment from HCR. Accordingly, HCR will receive all future royalties of the products, and none of these royalties will return to Nektar. We accounted for the Amendment as a modification of the existing arrangement, and therefore recorded the $15.0 million proceeds as an increase to the liability.

The sale of the Facility did not alter the 2012 or the 2020 Purchase and Sale Agreements, nor royalties payable under the related license agreements.

The following table shows the activity within the liability account of each arrangement (in thousands):


	Year-Ended December 31, 2025									Period from inception to December 31, 2025
	2012 Purchase and Sale Agreement			2020 Purchase and Sale Agreement			Total			2012 Purchase and Sale Agreement			2020 Purchase and Sale Agreement			Total
Liabilities related to the sales of future royalties—beginning balance	$	7,197		$	85,522		$	92,719		$	—		$	—		$	—
Royalty monetization proceeds		—			—			—			124,000			165,000			289,000
Non-cash royalty revenue		(7,894	)		(47,038	)		(54,932	)		(388,622	)		(202,743	)		(591,365	)
Non-cash interest expense		2,767			23,417			26,184			253,170			99,644			352,814
Payments to RPI		—			—			—			(10,000	)		—			(10,000	)
Loss on revaluation of liability related to the sale of future royalties		—			—			—			23,522			—			23,522
Liabilities related to the sales of future royalties – ending balance		2,070			61,901			63,971			2,070			61,901			63,971
Less: unamortized transaction costs		—			(814	)		(814	)		—			(814	)		(814	)
Liabilities related to the sales of future royalties, net	$	2,070		$	61,087		$	63,157		$	2,070		$	61,087		$	63,157

Organization and Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2025

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Shar

excluded shares underlying the weighted average outstanding stock options and RSUs, as follows:


	Year Ended December 31,
	2025		2024
Potentially dilutive securities		2,260,593		1,788,719

Pay vs Performance Disclosure - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2025

Dec. 31, 2024

Pay vs Performance Disclosure

Net Income (Loss)

$ (164,076)

$ (118,961)

^[1]

[1]	All share and per share amounts have been retrospectively adjusted to reflect a one-for-fifteen reverse stock split (see Note 8).

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Cash and cash equivalents

Gain on Sale of the Huntsville Manufacturing Facility - Schedule of Assumptions Used to Calculate the Fair Value of the Equity Method Investment (Details)	Dec. 31, 2025
Risk-free interest rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity Securities, FV-NI, Measurement Input	4.1
Dividend yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity Securities, FV-NI, Measurement Input	0
Volatility factor
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity Securities, FV-NI, Measurement Input	50

Subsequent Events - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	12 Months Ended
	Feb. 13, 2026	Mar. 11, 2026	Dec. 31, 2025	Dec. 31, 2024
Subsequent Event [Line Items]
Commissions costs			$ 1,150	$ 0
Subsequent Event \| Common Stock
Subsequent Event [Line Items]
Sale and issuance of shares	7,637,931
Offering per share price	$ 58
Subsequent Event \| 2026 Offering
Subsequent Event [Line Items]
Net proceeds from issuance of common stock	$ 432,000
Subsequent Event \| 2026 Offering \| Common Stock
Subsequent Event [Line Items]
Sale and issuance of shares	7,637,931
Offering per share price	$ 58
Subsequent Event \| 2026 Offering \| Pre-Funded Warrant
Subsequent Event [Line Items]
Number of warrants issued to be purchase common shares	293,103
Offering per share price	$ 57.9999
Subsequent Event \| November 2025 ATM Sales Agreement \| Common Stock
Subsequent Event [Line Items]
Sale and issuance of shares		639,131
Net proceeds from issuance of common stock		$ 44,100
Commissions costs		$ 1,400
Offering per share price		$ 71.15

Operating Leases - Schedule of Lease Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Leases [Abstract]
Operating lease expense	$ 7,155	$ 8,723
Variable lease expense	7,905	9,000
Total lease expense	$ 15,060	$ 17,723

Stock-Based Compensation - Additional Information (Details)	12 Months Ended
	Dec. 31, 2025 USD ($) $ / shares shares	Dec. 31, 2024 USD ($) $ / shares shares	Nov. 06, 2025 shares	Jun. 06, 2025 shares	May 23, 2025 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Change in control severance payment period for executives	12 months
Common stock reserved for issuance	3,300,607	4,571,228
Total unrecognized compensation costs \| $	$ 32,200,000
Recognized over a weighted-average period	2 years 9 months 18 days
Dividend yield	0.00%	0.00%
Total intrinsic value of options exercised \| $	$ 2,200,000	$ 0
Maximum 401(k) per employee, percentage of annual salary	60.00%
Matching 401(k) employer contribution, maximum amount \| $	$ 12,000	12,000
Compensation expense in connection with 401(k) retirement plan \| $	$ 700,000	$ 1,400,000
2017 Performance Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation plan's share limit reduction for every one restricted stock unit granted	1.5
Stock options term under equity incentive plans	8 years
Common stock reserved for issuance	353,240	551,727
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance	45,858	47,383
Amended and Restated 2017 Performance Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance				400,000	6,000,000
2025 Inducement Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock shares available for stock options grants (in shares)			250,000
Common stock reserved for issuance	231,690	0
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	0.00%
Employee Stock Option \| 2017 Performance Incentive Plan \| Employee \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period for stock-based compensation award granted	4 years
Employee Stock Option \| 2017 Performance Incentive Plan \| Employee \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period for stock-based compensation award granted	3 years
Employee Stock Option \| 2017 Performance Incentive Plan \| Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period for stock-based compensation award granted	1 year
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Offering period	6 months
Employee Stock Purchase Plan \| Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase price of common stock, percent	85.00%
Restricted Stock Units (RSU)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in dollars per share) \| $ / shares	$ 43.87	$ 16.35
Fair value of restricted stock vested \| $	$ 2,100,000	$ 2,800,000

Operating Leases - Schedule of Maturities of Operating Lease Receivables from Subleases (Details) $ in Thousands	Dec. 31, 2025 USD ($)
Leases [Abstract]
2026	$ 1,670
2027	1,729
2028	1,788
2029	1,846
2030 and thereafter	0
Gross Lease Receivable	$ 7,033

Liabilities Related to the Sales of Future Royalties - Additional Information (Details) $ in Millions				3 Months Ended	12 Months Ended
	Mar. 04, 2024 USD ($)	Dec. 16, 2020 USD ($)	Feb. 24, 2012 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)
2012 Purchase and Sale Agreement
Liability Related to the Sale of Future Royalties [Line Items]
Proceeds from sale of royalty rights			$ 124.0
2012 Purchase and Sale Agreement \| Future Royalties
Liability Related to the Sale of Future Royalties [Line Items]
Fair value of liabilities					$ 84.7
Non-cash loss on revaluation of liability related to the sale of future royalties				$ 23.5
Transaction costs related to revised royalty payments				$ 0.9
2020 Purchase and Sale Agreement
Liability Related to the Sale of Future Royalties [Line Items]
Proceeds from sale of royalty rights		$ 150.0			$ 15.0
Payment of transaction related to purchase and sale agreement		210.0
Payment of transaction related to purchase and sale agreement if threshold is not achieved		$ 240.0
Amount exchanged to remove cap on royalties	$ 15.0
2020 Purchase and Sale Agreement \| Measurement Input, Discount Rate
Liability Related to the Sale of Future Royalties [Line Items]
Royalties liability, measurement input					0.492
Pursuant to the 2012 Purchase and Sale Agreement
Liability Related to the Sale of Future Royalties [Line Items]
Payment made for milestone not achieved year one					$ 10.0
Payment made for milestone not achieved year two						$ 10.0

CONSOLIDATED BALANCE SHEETS - USD ($)
$ in Thousands

Dec. 31, 2025

Dec. 31, 2024

Current assets:

$ 15,116

$ 44,252

^[1]

Short-term investments

230,636

210,974

^[1]

Other current assets (including $429 and $0 as of December 31, 2025 and 2024, respectively, from a related party)

20,514

6,066

^[1]

Total current assets

266,266

261,292

^[1]

Long-term investments

13,869

^[1]

Property, plant and equipment, net

2,060

3,411

^[1]

Operating lease right-of-use assets

2,941

8,413

^[1]

Equity method investment in Gannet BioChem

3,491

12,218

^[1]

Other assets

5,648

4,647

^[1]

Total assets

280,406

303,850

^[1]

Current liabilities:

Accounts payable (including $137 and $0 as of December 31, 2025 and 2024, respectively, to a related party)

10,770

11,560

^[1]

Accrued expenses (including $994 and $3,403 as of December 31, 2025 and 2024, respectively, to a related party)

22,271

29,972

^[1]

Operating lease liabilities, current portion

20,495

19,868

^[1]

Total current liabilities

53,536

61,400

^[1]

Operating lease liabilities, less current portion

65,256

82,696

^[1]

63,157

91,776

^[1]

Other long-term liabilities

8,625

7,241

^[1]

Total liabilities

190,574

243,113

^[1]

Commitments and contingencies

Stockholders’ equity:

Preferred stock, $0.0001 par value; 10,000,000 shares authorized; no shares designated or outstanding at December 31, 2025 or 2024, respectively

^[1]

Common stock, $0.0001 par value; 390,000,000 shares and 300,000,000 shares authorized at December 31, 2025 and 2024, respectively; 20,378,832 shares and 12,937,308 shares issued at December 31, 2025 and 2024, respectively; 20,378,832 shares and 12,385,001 shares outstanding at December 31, 2025 and December 31, 2024, respectively

^[1]

Capital in excess of par value

3,850,099

3,659,885

^[1]

Treasury stock, at cost; 0 shares and 552,307 shares as of December 31, 2025 and 2024, respectively

^[1]

(3,000)

Accumulated other comprehensive income (loss)

^[1]

Accumulated deficit

(3,760,286)

(3,596,210)

^[1]

Total stockholders’ equity

89,832

60,737

^[1]

Total liabilities and stockholders’ equity

$ 280,406

$ 303,850

^[1]

[1]	All share and per share amounts have been retrospectively adjusted to reflect a one-for-fifteen reverse stock split (see Note 8).

Stockholders Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands					1 Months Ended		2 Months Ended	12 Months Ended
	Feb. 13, 2026	Nov. 12, 2025	Jul. 02, 2025	May 28, 2024	Mar. 11, 2026	Mar. 31, 2024	Oct. 31, 2025	Dec. 31, 2025	Dec. 31, 2024	Jul. 11, 2025	Jul. 01, 2025	Jun. 30, 2025	Jun. 06, 2025	Jun. 05, 2025
Subsidiary, Sale of Stock [Line Items]
Common stock, number of authorized								390,000,000	300,000,000				390,000,000	300,000,000
Proceeds from issuance of TCG pre-funded warrant								$ 0	$ 30,000
Treasury shares outstanding								0	552,307
Commissions costs								$ 1,150	$ 0
Aggregate maximum public offering amount								$ 300,000
Securities Purchase Agreement \| TCG Crossover Fund II, L.P.
Subsidiary, Sale of Stock [Line Items]
Proceeds from issuance of TCG pre-funded warrant						$ 30,000
Warrant exercised prior notice period						61 days
Effective date of warrant				Jun. 05, 2024
2025 Offering \| Jefferies LLC
Subsidiary, Sale of Stock [Line Items]
Sale and issuance of shares			4,893,618
Offering per share price			$ 23.5
Sale of stock upon exercise of option to purchase additional shares of common stock			638,298
Proceeds from offering, net			$ 107,200
Treasury shares outstanding												552,307
Common Stock \| April 2025 ATM Sales Agreement
Subsidiary, Sale of Stock [Line Items]
Sale and issuance of shares							1,273,923
Offering per share price							$ 58.87
Proceeds from offering, net							$ 72,500
Shares available for future issuance								0
Common Stock \| November 2025 ATM Sales Agreement
Subsidiary, Sale of Stock [Line Items]
Sale and issuance of shares								0
Aggregate maximum public offering amount		$ 110,000
Common Stock \| Underwritten Public Offering
Subsidiary, Sale of Stock [Line Items]
Sale and issuance of shares			4,893,618
Offering per share price			$ 23.5
Proceeds from offering, net			$ 107,200
Pre-Funded Warrant
Subsidiary, Sale of Stock [Line Items]
Exercise price of warrants						$ 0.0015
Pre-Funded Warrant \| Securities Purchase Agreement \| TCG Crossover Fund II, L.P.
Subsidiary, Sale of Stock [Line Items]
Number of warrants issued to be purchase common shares						1,666,667				886,667	780,000
Shares issued, price per share						$ 18
Maximum \| Securities Purchase Agreement \| TCG Crossover Fund II, L.P.
Subsidiary, Sale of Stock [Line Items]
Percentage of number of shares of warrant exercised						19.99%
Maximum \| Pre-Funded Warrant \| Securities Purchase Agreement \| TCG Crossover Fund II, L.P.
Subsidiary, Sale of Stock [Line Items]
Resale of common stock issuable upon exercise of warrant				1,666,667
Subsequent Event \| 2026 Offering
Subsidiary, Sale of Stock [Line Items]
Proceeds from offering, net	$ 432,000
Subsequent Event \| 2026 Offering \| Jefferies LLC
Subsidiary, Sale of Stock [Line Items]
Sale and issuance of shares	7,637,931
Offering per share price	$ 58
Sale of stock upon exercise of option to purchase additional shares of common stock	1,034,482
Proceeds from offering, net	$ 432,000
Commissions costs	$ 28,000
Subsequent Event \| Common Stock
Subsidiary, Sale of Stock [Line Items]
Sale and issuance of shares	7,637,931
Offering per share price	$ 58
Subsequent Event \| Common Stock \| November 2025 ATM Sales Agreement
Subsidiary, Sale of Stock [Line Items]
Sale and issuance of shares					639,131
Offering per share price					$ 71.15
Proceeds from offering, net					$ 44,100
Commissions costs					$ 1,400
Subsequent Event \| Common Stock \| 2026 Offering
Subsidiary, Sale of Stock [Line Items]
Sale and issuance of shares	7,637,931
Offering per share price	$ 58
Subsequent Event \| Pre-Funded Warrant \| 2026 Offering
Subsidiary, Sale of Stock [Line Items]
Exercise price of warrants	$ 0.0001
Subsequent Event \| Pre-Funded Warrant \| Underwritten Public Offering
Subsidiary, Sale of Stock [Line Items]
Number of warrants issued to be purchase common shares	293,103
Shares issued, price per share	$ 57.9999
Proceeds from issuance of TCG pre-funded warrant	$ 432,000
Affiliates \| Maximum \| Securities Purchase Agreement \| TCG Crossover Fund II, L.P.
Subsidiary, Sale of Stock [Line Items]
Percentage of number of shares of warrant exercised						9.99%

Stock-Based Compensation - Schedule of Black-Scholes Option-Pricing Model Assumptions Used to Calculate Fair Value of Employee Stock Options (Details) - $ / shares	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Share-Based Payment Arrangement [Abstract]
Average risk-free interest rate	3.80%	4.20%
Dividend yield	0.00%	0.00%
Average volatility factor	104.90%	91.70%
Weighted-average expected life	5 years 2 months 12 days	5 years 1 month 6 days
Weighted-average grant-date fair value of options granted (in dollars per share)	$ 34.48	$ 11.42

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2025

Dec. 31, 2024

^[1]

Revenue:

$ 55,232

$ 98,427

Research and development (including $2,636 and $277 for the year ended December 31, 2025 and 2024, respectively, from a related party)

Cost of goods sold

30,686

117,330

120,908

General and administrative

68,673

76,751

Restructuring and impairment

9,331

15,670

Gain on sale of the Huntsville manufacturing facility

(40,390)

Total operating costs and expenses

195,334

203,625

Loss from operations

(140,102)

(105,198)

Non-operating income (expense):

Non-cash interest expense on liabilities related to the sales of future royalties

(26,184)

(28,112)

Interest income

10,438

14,500

Other income (expense), net (including $1,110 and $0 for the year ended December 31, 2025 and 2024, respectively, from a related party)

361

(390)

Total non-operating income (expense), net

(15,385)

(14,002)

Loss before benefit for income taxes and equity method investment

(155,487)

(119,200)

Benefit for income taxes

(138)

(239)

Loss before equity method investment

(155,349)

(118,961)

Loss from equity method investment

(8,727)

Basic net loss per share (in dollars per share)

$ (164,076)

$ (118,961)

$ (9.73)

$ (8.68)

Diluted net loss per share (in dollars per share)

$ (9.73)

$ (8.68)

Weighted average shares outstanding used in computing basic net loss per share (in shares)

16,870,930

13,710,775

Weighted average shares outstanding used in computing diluted net loss per share (in shares)

16,870,930

13,710,775

Product sales

Revenue:

Non-cash royalty revenue related to the sales of future royalties

$ 0

$ 33,563

Revenue:

License, collaboration and other revenue

54,932

64,267

Revenue:

Organization, Consolidation and Presentation of Financial Statements [Abstract]

$ 300

$ 597

[1]	All share and per share amounts have been retrospectively adjusted to reflect a one-for-fifteen reverse stock split (see Note 8).

Organization and Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2025

Organization and Summary of Significant Accounting Policies

Note 1 — Organization and Summary of Significant Accounting Policies

Organization

On December 16, 2025, we announced data from the 36-week induction period of the ongoing Phase 2b REZOLVE-AA trial being conducted in 92 patients.

Sale of Manufacturing Facility

Basis of Presentation and Principles of Consolidation

We have prepared our Consolidated Financial Statements pursuant to U.S. generally accepted accounting principles (U.S. GAAP) and the rules and regulations of the Securities and Exchange Commissions.

Use of Estimates

Fair Value Measurements

Level 1 — Quoted prices in active markets for identical assets or liabilities.

Level 3 — Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

Related Parties

Cash, Cash Equivalents, and Investments in Marketable Securities

Accounts Receivable and Significant Customer Concentrations

Inventory and Significant Supplier Concentrations

Long-Lived Assets

See Note 10 for additional information regarding the impairment charges we recorded for our leased facilities and certain property and equipment.

Leases

Please see Note 5 for additional information regarding our leases.

Restructuring

Reverse Stock Split

Treasury Stock

Collaborative Arrangements

Revenue Recognition

Product sales

As a result of the sale of the Facility, we no longer recognize product sales of PEG reagents.

Non-cash royalty revenue

royalty revenue of $54.9 million and $64.3 million for the years ended December 31, 2025 and 2024, respectively, represents revenue for granting licenses for which we had satisfied in prior periods.

License, collaboration and other revenue

Research and Development Expense

Research and development costs are expensed as incurred and include salaries, benefits and other operating costs such as outside services, supplies and allocated overhead costs.

Non-cash Interest Expense on Liabilities Related to the Sales of Future Royalties

Equity Method Investment

Stock-Based Compensation

•

RSUs - The fair value of an RSU is equal to the closing price of our common stock on the grant date.

Income Taxes

For the years ended December 31, 2025 and 2024, our income tax benefit was immaterial.

Net Loss Per Share


	Year Ended December 31,
	2025		2024
Potentially dilutive securities		2,260,593		1,788,719

Comprehensive Loss

Recent Accounting Pronouncements

Income Taxes - Schedule of Reconciliation of our U.S. Federal Statutory Tax Amount and Rate to Effective Amount and Rate (Details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2025

Dec. 31, 2024

Income Tax Disclosure [Abstract]

Income tax benefit at federal statutory rate

$ (34,485)

$ (25,032)

State & local income taxes, net of federal income tax effect

Foreign tax effects

(295)

Effects of changes in tax laws or rates enacted in the current period

Effects of cross-border tax laws

Research credits

(781)

7,741

Change in valuation allowance

6,913

1,635

Expiration of net operating loss carryforwards

24,806

8,252

Non-cash interest expense on liabilities related to sales of future royalties

6,881

4,280

(4,085)

5,904

Non-cash royalty revenue related to sales of future royalties

(5,645)

Other

1,266

Changes in unrecognized tax benefits

(431)

Impairment of goodwill

Other adjustments

2,626

Benefit for income taxes

$ (138)

$ (239)

^[1]

U.S. Federal Statutory Tax Rate

21.00%

State & local income taxes, net of federal income tax effect

0.00%

Foreign tax effects

0.20%

Effects of changes in tax laws or rates enacted in the current period

0.00%

Effects of cross-border tax laws

0.00%

Research credits

0.50%

Changes in valuation allowances

(4.20%)

Changes in unrecognized tax benefits

(4.20%)

2.50%

Other

(0.80%)

0.30%

Expiration of net operating loss carryforwards

(15.20%)

Other adjustments

0.00%

Effective Tax Rate

0.10%

0.20%

[1]	All share and per share amounts have been retrospectively adjusted to reflect a one-for-fifteen reverse stock split (see Note 8).

Segment Reporting - Summary of Significant Expense Categories and Consolidated Net Loss (Details) - USD ($)
$ in Thousands

12 Months Ended

166 Months Ended

Dec. 31, 2025

Dec. 31, 2024

Dec. 31, 2025

Segment Reporting Information [Line Items]

Revenue

$ 55,232

$ 98,427

^[1]

Clinical development, contract manufacturing and other third party costs

Cost of goods sold

30,686

^[1]

69,419

76,850

Employee costs

46,003

40,204

Facilities costs

12,306

16,821

Other operating costs

44,727

42,047

Other segment expenses

22,879

37,407

Gain on sale of the Huntsville manufacturing facility

(40,390)

Total operating costs and expenses

195,334

203,625

^[1]

Loss from operations

(140,102)

(105,198)

^[1]

Non-operating income (expense):

Non-cash interest expense on liabilities related to sales of future royalties

(26,184)

(28,112)

^[1]

$ (352,814)

Interest income

10,438

14,500

^[1]

Total non-operating income (expense), net

361

(390)

^[1]

(15,385)

(14,002)

^[1]

Loss before benefit for income taxes and equity method investment

(155,487)

(119,200)

^[1]

Benefit for income taxes

(138)

(239)

^[1]

Loss before equity method investment

(155,349)

(118,961)

^[1]

Loss from equity method investment

(8,727)

^[1]

Rezpegaldesleukin (IL-2 receptor agonist/regulatory T cell agent)

(164,076)

(118,961)

^[1]

Clinical development, contract manufacturing and other third party costs

51,531

49,382

NKTR-255 (IL-15 receptor agonist)

Clinical development, contract manufacturing and other third party costs

6,486

15,795

NKTR-0165 (tumor necrosis factor receptor type II agonist)

Clinical development, contract manufacturing and other third party costs

9,569

9,339

Discovery Research and Other Programs

Clinical development, contract manufacturing and other third party costs

$ 1,833

$ 2,334

[1]	All share and per share amounts have been retrospectively adjusted to reflect a one-for-fifteen reverse stock split (see Note 8).

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Dec. 31, 2025
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Stockholders' Equity

12 Months Ended

Dec. 31, 2025

Equity [Abstract]

Stockholders' Equity

Note 8 — Stockholders’ Equity

On June 6, 2025, we filed a Certificate of Amendment to the Certificate of Incorporation, or the Increase in Shares Amendment, to increase the number of authorized shares of the Company’s common stock from 300,000,000 shares to 390,000,000 shares. The increase in authorized shares amendment was previously approved by our stockholders at the Annual Meeting of Stockholders held on May 23, 2025 and became effective upon its filing.

On June 6, 2025, we also filed a Certificate of Amendment to Nektar’s Certificate of Incorporation (the Reverse Stock Split Amendment) to effect a reverse stock split of our common stock at a ratio of one-for-fifteen (the Reverse Stock Split). The Reverse Stock Split Amendment became effective as of 11:59 p.m. Eastern Time on June 8, 2025 (the Effective Time), at which time every fifteen shares of our common stock issued and outstanding immediately prior to the Effective Time were combined into one share of common stock. No fractional shares of our common stock were issued as a result of the Reverse Stock Split. Instead, any fractional shares resulting from the Reverse Stock Split were rounded up at the participant level if such shares of our common stock (including shares subject to issuance upon exercise of the pre-funded warrant) were held directly or rounded down to the nearest whole share of our common stock, if such shares were subject to an award granted under the 2017 Amended and Restated Performance Incentive Plan. Upon effectiveness of the Reverse Stock Split, the number of shares of common stock for which each outstanding option and pre-funded warrant to purchase common stock is exercisable was adjusted, and the exercise price of each outstanding option and pre-funded warrant to purchase common stock was adjusted. The Reverse Stock Split did not change the par value per share or the authorized number of shares of common stock and preferred stock. As a result of the Reverse Stock Split, we have retrospectively recast prior periods for shares of our common stock, including those issued, outstanding and treasury stock, weighted-average shares outstanding and loss per share.

TCG Pre-Funded Warrant

In March 2024, we issued a pre-funded warrant to purchase an aggregate of 1,666,667 shares of our common stock to TCG Crossover Fund II, L.P. (TCG) at a price of $18.00 per share for gross proceeds of $30.0 million. Transaction costs were immaterial. The TCG Pre-funded Warrant had an exercise price of $0.0015 per share and was exercisable at any time after the original issuance date. TCG could not exercise the warrant if TCG, together with its affiliates, would beneficially own more than 9.99% of the number of shares of our common stock outstanding immediately after giving effect to such exercise. TCG could increase or decrease this percentage not in excess of 19.99% by providing at least 61 days prior notice to the Company. On May 28, 2024, we filed with the SEC a registration statement on Form S-3 (file no. 333-279760) registering for resale of up to 1,666,667 shares of our common stock issuable upon exercise of the TCG Pre-funded Warrant. The registration statement became effective on June 5, 2024.

We classified the TCG Pre-funded Warrant as a component of permanent equity in our Consolidated Balance Sheets as it is a freestanding financial instrument that was immediately exercisable, does not embody an obligation for the Company to repurchase its own shares and permits the holder to receive a fixed number of shares of common stock upon exercise. All of the shares underlying the TCG Pre-funded Warrant have been included in the weighted-average number of shares of common stock used to calculate net loss per share attributable to common stockholders because the shares may be issued for little or no consideration, are fully vested and are exercisable after the original issuance date of the TCG Pre-funded Warrant.

On July 1, and July 11, 2025, TCG exercised the TCG Pre-funded Warrant to purchase 780,000 and 886,667 shares of common stock, respectively. Exercise proceeds are immaterial. As a result of these exercises, no shares remain issuable under the warrant.

Secondary Offerings

On July 2, 2025, pursuant to the April 2025 Shelf Registration Statement, we completed the sale and issuance of 4,893,618 shares of our common stock in an underwritten public offering (the 2025 Offering) at a price of $23.50 per share, which included 638,298 shares sold upon exercise in full by the underwriters of their option to purchase additional shares of common stock in the 2025 Offering. The net proceeds to the Company from the 2025 Offering totaled approximately $107.2 million, after deducting underwriting discounts and commissions and other offering costs.

In connection with the 2025 Offering, we re-issued all 552,307 shares held in treasury stock as of June 30, 2025.

On February 13, 2026, pursuant to the November 2025 Shelf Registration Statement, we completed the sale and issuance of 7,637,931 shares of common stock at a price of $58.00 per share, which included 1,034,482 shares sold upon exercise in full by the underwriters of their option to purchase additional shares of common stock in the 2026 Offering, and 293,103 pre-funded warrants at price of $57.9999 per pre-funded warrant in an underwritten public offering. The estimated net proceeds from the 2026 Offering totaled approximately $432.0 million, after deducting underwriting discounts and

commissions and estimated offering expenses of approximately $28.0 million. Each pre-funded warrant has an exercise price of $0.0001 per share.

At-The-Market Offerings

On November 12, 2025, we also entered into the November 2025 ATM Sales Agreement with Piper Sandler & Co. and BTIG, LLC, relating to the sale of our common stock having an aggregate offering price of up to $110.0 million in an “at-the-market” offering. As of December 31, 2025, no shares were issued under the November 2025 ATM Sales Agreement. From February 20, 2026 through March 11, 2026, we issued 639,131 shares of our common stock under the November 2025 ATM Sales Agreement at a weighted average price of $71.15 per share for net proceeds of $44.1 million after deducting related commissions of approximately $1.4 million.

Shares Reserve for Issuance

Shares of common stock reserved for future issuance are as follows:


	December 31,
	2025		2024
Stock options and RSUs outstanding		2,669,819		2,305,451
Shares reserved for TCG Pre-funded Warrant		—		1,666,667
Shares available for future grant under the 2017 Performance Incentive Plan		353,240		551,727
Shares available for future grant under the 2025 Inducement Plan		231,690		—
Shares available for issuance under the employee stock purchase plan		45,858		47,383
Total common stock reserved for issuance		3,300,607		4,571,228

The entire disclosure for equity.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-8A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (b)
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Restructuring and Impairment - Additional information (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2025	Jun. 30, 2024	Dec. 31, 2024
Restructuring Cost and Reserve [Line Items]
Impairment charges			$ 8.3
Third St. Facility
Restructuring Cost and Reserve [Line Items]
Impairment charges			4.4
Mission Bay Facility
Restructuring Cost and Reserve [Line Items]
Impairment charges	$ 4.4		3.9
Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Contract termination and other costs included in accrued expenses	$ 2.6		$ 2.8
Measurement Input, Market Participant Subtenant Borrowing Rate
Restructuring Cost and Reserve [Line Items]
Operating lease, measurement input		6.20%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Restructuring and Related Activities [Abstract]

Restructuring and Impairment (Tables)

12 Months Ended

Dec. 31, 2025

Schedule of Restructuring and Impairment

In connection with our 2022 and 2023 Restructuring Plans, restructuring and impairment includes the following (in thousands):


	Year ended December 31,
	2025		2024
Impairment of right-of-use assets and property, plant and equipment	$	4,441	$	8,329
Contract termination costs		4,890		7,341
Restructuring and impairment	$	9,331	$	15,670


	Year-Ended December 31, 2025
	Operating Lease Right-of-Use Assets		Property, Plant and Equipment		Total
Net book value of impaired sublease assets	$	3,817	$	624	$	4,441
Less: Fair value of impaired facilities — Level 3 of Fair Value Hierarchy		—		—		—
Total impairment of right-of-use assets and property, plant and equipment	$	3,817	$	624	$	4,441


	Year Ended December 31, 2024
	Operating Lease Right-of-Use Assets			Property, Plant and Equipment			Total
Net book value of impaired sublease assets	$	12,506		$	1,897		$	14,403
Less: Fair value of impaired sublease assets — Level 3 of Fair Value Hierarchy		(5,219	)		(855	)		(6,074	)
Total impairment of right-of-use assets and property, plant and equipment	$	7,287		$	1,042		$	8,329

The following are reconciliations of the contract termination costs, for the years ended December 31, 2025 and 2024 (in thousands):


	Year Ended December 31,
Liability balances as of December 31, 2023	$	5,542
Expense recognized during the period		7,341
Payments during the period		(3,805	)
Liability balances as of December 31, 2024		9,078
Expense recognized during the period		4,890
Payments during the period		(3,286	)
Liability balances as of December 31, 2025	$	10,682

Equity Method Investment (Tables)

12 Months Ended

Dec. 31, 2025

Equity Method Investments and Joint Ventures [Abstract]

Schedule Of Equity Method Investments

Our loss from our investment in Gannet BioChem for the twelve months ended December 31, 2025 is as follows (in thousands):


	Year Ended December 31, 2025
Claim on net assets of Gannet BioChem - beginning of period	$	12,218
Claim on net assets of Gannet BioChem - end of period		3,491
Change in claim on net assets of Gannet BioChem	$	(8,727	)

Income Taxes - Schedule of Significant Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Deferred tax assets:
Net operating loss carryforwards	$ 625,497	$ 587,528
Research and other credits	137,530	135,871
Net capital loss carryforwards	39,648	39,648
Operating lease liabilities	24,517	22,767
Stock-based compensation	18,277	19,619
Capitalized research and development costs	35,183	45,607
Liabilities related to the sales of future royalties	0	2,020
Other	12,830	9,402
Deferred tax assets before valuation allowance	893,482	862,462
Valuation allowance for deferred tax assets	(892,432)	(859,084)
Total deferred tax assets	1,050	3,378
Deferred tax liabilities:
Investment in foreign subsidiary	(575)	(511)
Other	(1,050)	(3,377)
Total deferred tax liabilities	(1,625)	(3,888)
Net deferred tax assets (liabilities)	$ (575)	$ (510)

License and Collaboration Agreements - Additional Information (Details)		1 Months Ended	12 Months Ended
	Feb. 12, 2024 USD ($) shares	Apr. 30, 2018 USD ($) shares	Dec. 31, 2023 USD ($)	Dec. 31, 2025 USD ($) Milestones
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Contract asset				$ 7,000,000
Bristol Myers Squibb Company \| Purchase Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Shares issued (in shares) \| shares		552,307
Sale of stock consideration received		$ 850,000,000
Other Partner
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential future additional payments for development milestones				$ 40,000,000
Nektar 0165 \| Biolojic Design Company [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Payable For Newdrug Investigle Milestone			$ 3,000,000
Number of Milestone \| Milestones				0
Nektar 0165 \| Maximum \| Biolojic Design Company [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential future additional payments for development milestones			35,000,000
Payment For Development Milestones			$ 18,000,000
Bristol Myers Squibb Collaboration Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Sale of stock shares repurchased \| shares	552,307
Sale of stock repurchased cash consideration	$ 3,000,000
Nektar's \| Bristol Myers Squibb Collaboration Agreement \| Nektar 214
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront and milestone payments received from license agreements		$ 1,000,000,000

Segment Reporting - Schedule of Other Segment Expense Items Included within Net Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Impairment of right-of-use assets and property, plant and equipment	$ 4,441	$ 8,329
Stock-based compensation	12,649	21,612
Depreciation and amortization expense	1,026	4,391
Total other segment expenses	22,879	37,407
Other Segment
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Impairment of right-of-use assets and property, plant and equipment	4,441	8,329
Contract termination costs	4,890	7,341
Stock-based compensation	12,649	19,666
Depreciation and amortization expense	899	2,071
Total other segment expenses	$ 22,879	$ 37,407

Cybersecurity Risk Management, Strategy, and Governance	12 Months Ended
Cybersecurity Risk Management, Strategy, and Governance	Dec. 31, 2025
Cybersecurity Risk Management, Strategy, and Governance [Abstract]
Cybersecurity Risk Management Processes for Assessing, Identifying, and Managing Threats [Text Block]	Item 1C. Cybersecurity. Cyber Risk Management and Strategy The Company, under the oversight of the audit committee of the board of directors, has implemented and maintains an enterprise risk management process, which includes periodic assessments of various risk categories, including cyber risks, across the Company. Our process for assessing, identifying, and managing risks from cybersecurity threats is informed by industry standards and supported by cybersecurity technologies, including third-party security solutions, monitoring, and alerting tools, designed to monitor, identify, and address cybersecurity risks. We leverage a managed security service provider and also engage with other third-party providers and consultants to support our cyber risk management efforts, including through periodic security testing. We have a process to assess and review the cybersecurity practices of information technology third-party vendors and service providers, including through review of applicable certifications, security reports, and vendor questionnaires and contractual requirements, as appropriate. Governance Related to Cybersecurity Risks Our cyber risk management program and related operations and processes are directed by the Head of IT in consultation with the legal team and our third-party security advisor. Currently, the Head of IT role is held by an individual who has over 20 years of information technology experience. The Head of IT reports to the Chief People Officer. The Head of IT meets with the Chief People Officer and the legal team to periodically to discuss and review our cybersecurity risk management processes and to address matters related to potential cybersecurity and information technology risks, with input from the Company’s third-party technology providers, as appropriate. In addition, the Head of IT has regular meetings with our managed security service provider to inform our cyber risk management processes and reporting to management. The Head of IT, working with the Chief People Officer and the legal team, provides periodic reports on cybersecurity and information technology matters to the audit committee, which is responsible for reviewing and overseeing the Company’s risk management process, including cybersecurity risks. The Chief People Officer and the legal team along with the audit committee periodically report on cybersecurity risk management to the full board of directors. The board of directors, as a whole and through its committees, has responsibility for the periodic review and oversight of information technology risks, including cybersecurity risks. Our enterprise risk management program is overseen by a risk management committee comprised of senior managers across key functional areas that cover cybersecurity and information technology matters. This committee provides periodic reports and updates, as needed, to the board of directors or one of its designated committees. In collecting information on enterprise risk, cybersecurity is included as a designated risk category, and the results of our enterprise risk assessment processes, including risks related to cybersecurity, are also discussed with the audit committee and among senior management on a periodic basis. We have not identified any cybersecurity incidents or threats that have materially affected us or are reasonably likely to materially affect us, including our business strategy, results of operations, or financial condition. For more information regarding cybersecurity risks that may affect or Company, see “Item 1A. Risk Factors” included in this Report.
Cybersecurity Risk Management Third Party Engaged [Flag]	true
Cybersecurity Risk Third Party Oversight and Identification Processes [Flag]	true
Cybersecurity Risk Board of Directors Oversight [Text Block]	The Company, under the oversight of the audit committee of the board of directors, has implemented and maintains an enterprise risk management process, which includes periodic assessments of various risk categories, including cyber risks, across the Company. Our process for assessing, identifying, and managing risks from cybersecurity threats is informed by industry standards and supported by cybersecurity technologies, including third-party security solutions, monitoring, and alerting tools, designed to monitor, identify, and address cybersecurity risks.
Cybersecurity Risk Board Committee or Subcommittee Responsible for Oversight [Text Block]	The Company, under the oversight of the audit committee of the board of directors, has implemented and maintains an enterprise risk management process, which includes periodic assessments of various risk categories, including cyber risks, across the Company.
Cybersecurity Risk Process for Informing Board Committee or Subcommittee Responsible for Oversight [Text Block]	The board of directors, as a whole and through its committees, has responsibility for the periodic review and oversight of information technology risks, including cybersecurity risks.
Cybersecurity Risk Role of Management [Text Block]	Our cyber risk management program and related operations and processes are directed by the Head of IT in consultation with the legal team and our third-party security advisor. Currently, the Head of IT role is held by an individual who has over 20 years of information technology experience. The Head of IT reports to the Chief People Officer. The Head of IT meets with the Chief People Officer and the legal team to periodically to discuss and review our cybersecurity risk management processes and to address matters related to potential cybersecurity and information technology risks, with input from the Company’s third-party technology providers, as appropriate. In addition, the Head of IT has regular meetings with our managed security service provider to inform our cyber risk management processes and reporting to management. The Head of IT, working with the Chief People Officer and the legal team, provides periodic reports on cybersecurity and information technology matters to the audit committee, which is responsible for reviewing and overseeing the Company’s risk management process, including cybersecurity risks.
Cybersecurity Risk Management Positions or Committees Responsible [Flag]	true
Cybersecurity Risk Management Positions or Committees Responsible [Text Block]	The Head of IT meets with the Chief People Officer and the legal team to periodically to discuss and review our cybersecurity risk management processes and to address matters related to potential cybersecurity and information technology risks, with input from the Company’s third-party technology providers, as appropriate.
Cybersecurity Risk Management Positions or Committees Responsible Report to Board [Flag]	true
Cybersecurity Risk Management Expertise of Management Responsible [Text Block]	Currently, the Head of IT role is held by an individual who has over 20 years of information technology experience. The Head of IT reports to the Chief People Officer.
Cybersecurity Risk Process for Informing Management or Committees Responsible [Text Block]	The Head of IT, working with the Chief People Officer and the legal team, provides periodic reports on cybersecurity and information technology matters to the audit committee, which is responsible for reviewing and overseeing the Company’s risk management process, including cybersecurity risks.

CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($)
$ in Thousands

Total

Secondary Offering

At-the-Market Offering

Common Shares

Secondary Offering

Common Shares

At-the-Market Offering

Treasury Stock

Secondary Offering

Capital in Excess of Par Value

^[1]

Capital in Excess of Par Value

Secondary Offering

^[1]

Capital in Excess of Par Value

At-the-Market Offering

^[1]

Accumulated Other Comprehensive Income (Loss)

Accumulated Deficit

Beginning balance (in shares) at Dec. 31, 2023

^[1]

12,757,984

Beginning balance at Dec. 31, 2023

$ 130,987

$ 1

^[1]

$ 3,608,155

$ 80

$ (3,477,249)

Increase (Decrease) in Stockholders' Equity [Roll Forward]

Shares issued under equity compensation plans (in shares)

^[1]

179,324

Shares issued under equity compensation plans

118

Repurchase of common stock from Bristol-Myers Squibb (in shares)

21,612

^[1]

(552,307)

552,307

Repurchase of common stock from Bristol-Myers Squibb

(3,000)

$ (3,000)

Issuance of prefunded warrant

30,000

Comprehensive income (loss)

$ (118,980)

(19)

(118,961)

Ending balance (in shares) at Dec. 31, 2024

12,385,001

^[1]

Ending balance at Dec. 31, 2024

$ 60,737

^[2]

$ 1

^[1]

$ (3,000)

3,659,885

(3,596,210)

Ending balance (in shares) at Dec. 31, 2024

552,307

^[1]

Increase (Decrease) in Stockholders' Equity [Roll Forward]

Shares issued under equity compensation plans (in shares)

^[1]

159,623

Shares issued under equity compensation plans

$ 864

864

Shares issued under offering, net of underwriting discounts and offering costs (in shares)

12,649

^[1]

4,893,618

1,273,923

(552,307)

Shares issued under offering, net of underwriting discounts and offering costs

$ 107,160

$ 72,540

$ 1

^[1]

$ 3,000

$ 104,159

$ 72,540

Shares issued under prefunded warrant exercise (in shares)

^[1]

1,666,667

Issuance of prefunded warrant

Comprehensive income (loss)

$ (164,120)

(44)

(164,076)

Ending balance (in shares) at Dec. 31, 2025

20,378,832

^[1]

Ending balance at Dec. 31, 2025

$ 89,832

$ 2

^[1]

$ 3,850,099

$ 17

$ (3,760,286)

Ending balance (in shares) at Dec. 31, 2025

[1]	All share and per share amounts have been retrospectively adjusted to reflect a one-for-fifteen reverse stock split (see Note 8).
[2]	All share and per share amounts have been retrospectively adjusted to reflect a one-for-fifteen reverse stock split (see Note 8).

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2025

Dec. 31, 2024

Statement of Comprehensive Income [Abstract]

Net unrealized loss on available-for-sale investments

$ (164,076)

$ (118,961)

^[1]

Other comprehensive income (loss):

(18)

(15)

Net foreign currency translation adjustment

(26)

(4)

Other comprehensive loss

(44)

(19)

Comprehensive loss

$ (164,120)

$ (118,980)

[1]	All share and per share amounts have been retrospectively adjusted to reflect a one-for-fifteen reverse stock split (see Note 8).

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

Amount after tax and reclassification adjustments of other comprehensive income (loss).

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Income Taxes - Schedule of Income (Loss) Before Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Income Tax Disclosure [Abstract]
Domestic	$ (164,576)	$ (119,227)
Foreign	362	27
Loss before benefit for income taxes and equity method investment	$ (164,214)	$ (119,200)

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Preferred stock, par value (in dollars per share) | $ / shares

CONSOLIDATED BALANCE SHEETS (Parenthetical)
$ in Thousands

12 Months Ended

Dec. 31, 2025

USD ($)

$ / shares

Dec. 31, 2024

USD ($)

$ / shares

Other current assets | $

$ 20,514

$ 6,066

^[1]

$ 0.0001

Preferred stock, shares authorized (in shares)

10,000,000

Preferred stock, shares designated (in shares)

Preferred stock, shares outstanding (in shares)

Common stock, par value (in dollars per share) | $ / shares

$ 0.0001

Common stock, shares authorized (in shares)

390,000,000

300,000,000

Common stock, shares issued (in shares)

20,378,832

12,937,308

Common stock, shares outstanding (in shares)

20,378,832

12,385,001

Accrued expenses (including $994 and $3,403 as of December 31, 2025 and 2024, respectively, to a related party) | $

$ 22,271

$ 29,972

^[1]

Accounts payable (including $137 and $0 as of December 31, 2025 and 2024, respectively, to a related party) | $

$ 10,770

$ 11,560

^[1]

Treasury stock, shares

552,307

Reverse stock split

one-for-fifteen reverse stock split

Accrued expenses (including $994 and $3,403 as of December 31, 2025 and 2024, respectively, to a related party) | $

0.07

Related Party

Other current assets | $

$ 429

$ 0

994

3,403

Accounts payable (including $137 and $0 as of December 31, 2025 and 2024, respectively, to a related party) | $

$ 137

$ 0

[1]	All share and per share amounts have been retrospectively adjusted to reflect a one-for-fifteen reverse stock split (see Note 8).

Segment Reporting

12 Months Ended

Dec. 31, 2025

Segment Reporting [Abstract]

Segment Reporting

Note 14 — Segment Reporting

We operate in one business segment which focuses on applying our expertise to develop novel drug candidates. Our business offerings have similar economics and other characteristics, including the nature of products and manufacturing processes, types of customers, distribution methods and regulatory environment. We are comprehensively managed as one business segment by our Chief Executive Officer, who is our chief operating decision maker (CODM).

The CODM assesses the performance of the Company and decides how to allocate resources based upon net loss that is also reported within the Consolidated Statements of Operations. The measure of segment assets that is reviewed by the CODM is reported within the Consolidated Balance Sheet as total assets.

The following is a summary of the significant expense categories and consolidated net loss details provided to the CODM (in thousands):


	Year Ended December 31,
	2025			2024
Revenue:	$	55,232		$	98,427
Operating costs and expenses:
Cost of goods sold		—			30,686
Clinical development, contract manufacturing and other third party costs
Rezpegaldesleukin (IL-2 receptor agonist/regulatory T cell agent)		51,531			49,382
NKTR-255 (IL-15 receptor agonist)		6,486			15,795
NKTR-0165 (tumor necrosis factor receptor type II agonist)		9,569			9,339
Discovery research and other programs		1,833			2,334
Total clinical development, contract manufacturing and other third party costs		69,419			76,850
Employee costs (a)(b)		46,003			40,204
Facilities costs (a)		12,306			16,821
Other operating costs (a)(c)		44,727			42,047
Other segment expenses		22,879			37,407
Gain on sale of the Huntsville manufacturing facility		—			(40,390	)
Total operating costs and expenses		195,334			203,625
Loss from operations		(140,102	)		(105,198	)
Non-operating income (expense):
Non-cash interest expense on liabilities related to sales of future royalties		(26,184	)		(28,112	)
Interest income		10,438			14,500
Other income (expense), net		361			(390	)
Total non-operating income (expense), net		(15,385	)		(14,002	)
Loss before benefit for income taxes and equity method investment		(155,487	)		(119,200	)
Benefit for income taxes		(138	)		(239	)
Loss before equity method investment		(155,349	)		(118,961	)
Loss from equity method investment		(8,727	)		—
Net loss	$	(164,076	)	$	(118,961	)

Other segment expense items included within net loss include the following (in thousands):


	Year Ended December 31,
	2025		2024
Impairment of right-of-use assets and property, plant and equipment	$	4,441	$	8,329
Contract termination costs		4,890		7,341
Stock-based compensation (a)		12,649		19,666
Depreciation and amortization expense (a)		899		2,071
Total other segment expenses	$	22,879	$	37,407

Includes compensation and benefits for our employees and costs for our contractors and temporary workers.

Includes legal and patent expenses, information technology infrastructure and other costs, professional accounting, insurance, travel and entertainment and other third-party services and expenses.

Our revenue has been derived primarily from customers in the pharmaceutical and biotechnology industries. Revenue from Baxalta (a subsidiary of Takeda Pharmaceutical Company Limited), AstraZeneca, and UCB represented 45%, 37%, and 14% of our revenue, respectively, for the year ended December 31, 2025. Revenue from UCB, Baxalta, AstraZeneca, Pfizer Inc., and Roche represented 39%, 18%, 17%, 12% and 10% of our revenue, respectively, for the year ended December 31, 2024.

Revenue by geographic area is based on the headquarters or shipping locations of our partners. The following table sets forth revenue by geographic area (in thousands):


	Year Ended December 31,
	2025		2024
United States	$	—	$	1,375
Rest of World		55,232		97,052
Total revenue	$	55,232	$	98,427

At December 31, 2025 and 2024, all of our property, plant and equipment was located in the United States.

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

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Share-Based Payment Arrangement [Abstract]

Stock-Based Compensation

12 Months Ended

Dec. 31, 2025

Stock-Based Compensation

Note 12 — Stock-Based Compensation

2017 Performance Incentive Plan

Our 2017 Performance Incentive Plan, as amended and restated, (2017 Plan) provides for the issuance of our common stock to members of the Board of Directors, officers or employees, certain consultants and advisors and our subsidiaries. On May 23, 2025, our shareholders approved an amendment to the Amended and Restated 2017 Performance Incentive Plan to increase the aggregate number of shares of common stock authorized for issuance thereunder by 6,000,000 shares, which were subsequently adjusted to 400,000 shares due to the effect of the Reverse Stock Split. Under the 2017 Plan, we may issue stock options, restricted stock, performance stock, stock units, stock appreciation rights and other similar types of awards. Shares issued for RSUs, PSUs or any other “full-value award” are counted against the share limit as 1.5 shares for every one share granted in connection with the award.

We have granted non-qualified stock options and RSUs to employees, officers, and non-employee directors. For our employees, the requisite service period is generally three to four years. For our directors, the requisite service is generally one year. The maximum term of a stock option is eight years from the date of grant. The per share exercise price of an option generally may not be less than the fair market value of a share of our common stock on the NASDAQ Stock Market on the date of grant.

Under our Change in Control Plan (the CIC Plan), in the event of a change of control of Nektar and a subsequent termination of employment initiated by us or a successor company other than for Cause (as defined in the CIC Plan) within twelve months following a change of control, our employees are entitled to full acceleration of their unvested equity awards. Our Chief Executive Officer, Senior Vice Presidents and Vice Presidents (including Principal Fellows) are also entitled to full acceleration of unvested equity awards if the termination is initiated by the employee for a Good Reason Resignation (as defined in the CIC Plan) within twelve months following a change of control. Additionally, non-employee directors would also be entitled to full acceleration of vesting of all outstanding stock awards in the event of a change of control transaction.

2025 Inducement Plan

On November 6, 2025, the Board of Directors approved and adopted the 2025 Inducement Plan, to reserve 250,000 shares of common stock to be used exclusively for the grants of equity awards to individuals who were not previously an employee or non-employee director of Nektar (or following a bona fide period of non-employment), as an inducement material to such individual's entering into employment with Nektar, pursuant to Nasdaq Listing Rule 5635(c)(4). The 2025 Inducement Plan was adopted without stockholder approval pursuant to Nasdaq Listing Rule 5635(c)(4) and will be administered by the Organization and Compensation Committee of the Board of Directors.

Employee Stock Purchase Plan

Under the terms of our Employee Stock Purchase Plan (ESPP), employees may purchase shares of our common stock based on a percentage of their compensation subject to certain limits. Shares are purchased at 85% of the lower of the closing price on either the first day or last day of each six-month offering period.

Stock-Based Compensation Expense

We recognize total stock-based compensation expense in our Consolidated Statements of Operations as follows (in thousands):


	Year Ended December 31,
	2025		2024
Cost of goods sold	$	—	$	1,946
Research and development		5,444		8,161
General and administrative		7,205		11,505
Total stock-based compensation	$	12,649	$	21,612

Stock-based compensation expense resulting from our ESPP was not significant in the years ended December 31, 2025 and 2024.

As of December 31, 2025, total unrecognized compensation costs of $32.2 million related to unvested stock-based compensation awards are expected to be recognized as expense over a weighted-average period of 2.8 years.

Black-Scholes Assumptions

The following table lists the Black-Scholes option-pricing model assumptions used to calculate the fair value of employee and director stock options, as well as the resulting grant-date fair value:


	Year Ended December 31,
	2025			2024
Average risk-free interest rate		3.8	%		4.2	%
Dividend yield		0.0	%		0.0	%
Average volatility factor		104.9	%		91.7	%
Weighted-average expected life	5.2 years			5.1 years
Weighted-average grant-date fair value of options granted	$	34.48		$	11.42

The average risk-free interest rate is based on the U.S. treasury yield curve in effect at the time of grant for periods commensurate with the expected life of the stock-based award. We have never paid dividends, nor do we expect to pay dividends in the foreseeable future; therefore, we used a dividend yield of zero. Our estimate of expected volatility is based on the daily historical trading data of our common stock at the time of grant over a historical period commensurate with the expected life of the stock-based award. We estimated the weighted-average expected life based on the contractual and vesting terms of the stock options, as well as historical cancellation and exercise data.

Summary of Stock Option Activity

The table below presents a summary of stock option activity under our equity incentive plans (in thousands, except for share, per share, and contractual life information):


						Weighted-
				Weighted-		Average
				Average		Remaining
	Number			Exercise		Contractual		Aggregate
	of			Price		Life		Intrinsic
	Shares			per Share		(in Years)		Value(1)
Outstanding at December 31, 2024		2,203,927		$	83.73
Options granted		529,888			43.60
Options exercised		(76,013	)		10.50
Options forfeited & canceled		(196,083	)		309.89
Outstanding at December 31, 2025		2,461,719		$	59.34		5.09	$	42,513

Exercisable at December 31, 2025		1,164,061		$	93.36		4.74	$	19,583

(1)

Aggregate intrinsic value represents the difference between the exercise price of the option and the closing market price of our common stock on December 31, 2025.

The intrinsic value of options exercised during the year ended December 31, 2025 was $2.2 million. The intrinsic value of options exercised during the year ended 2024 was not significant.

Summary of RSU Activity

A summary of RSU award activity is as follows:


				Weighted-
				Average
				Grant
				Date Fair
	Units Issued			Value
Unvested at December 31, 2024		101,524		$	105.31
Granted		195,943			43.87
Vested and released		(82,085	)		87.03
Forfeited and canceled		(7,282	)		99.68
Unvested at December 31, 2025		208,100		$	54.01

The weighted-average grant-date fair values of RSUs granted during the years ended December 31, 2025 and 2024 were $43.87 and $16.35, respectively. The fair value of RSUs that vested in the years ended December 31, 2025 and 2024 totaled $2.1 million and $2.8 million, respectively.

401(k) Retirement Plan

We sponsor a 401(k) retirement plan whereby eligible employees may elect to contribute up to the lesser of 60% of their annual compensation or the statutorily prescribed annual limit allowable under Internal Revenue Service regulations. The 401(k) plan permits us to make matching contributions on behalf of all participants, up to a maximum of $12,000 per participant for the years ended December 31, 2025 and 2024. For the years ended December 31, 2025 and 2024, we recognized $0.7 million, and $1.4 million, respectively, of compensation expense in connection with our 401(k) retirement plan.

Equity Method Investment

12 Months Ended

Dec. 31, 2025

Equity Method Investments and Joint Ventures [Abstract]

Equity Method Investment

Note 4 — Equity Method Investment

As discussed in Note 1, on December 2, 2024, we completed the sale of the Facility and certain other manufacturing assets related thereto, including the assignment of our existing manufacturing and supply obligations, to Gannet BioChem, an affiliate of Ampersand, via the APA, for consideration of $64.7 million in cash, net of transaction costs, and an equity interest in Gannet BioChem.

We own 20.0 million common units of Gannet BioChem at $1.00 per unit, representing 100% of the common units outstanding at both closing of the sale of the Facility and at December 31, 2025, and Ampersand owns 81.5 million preferred units at $1.00 per unit, representing 100% of the preferred units outstanding at closing and 99.7% of the preferred units outstanding as of December 31, 2025. Gannet BioChem has reserved 11.3 million appreciation rights for issuance to its officers, employees, directors and consultants, which may only be settled upon a “company sale” as defined by Gannet BioChem’s equity plan and convert to common units in determining their distribution, less the “base value”, which is equal to the fair value of the common units as determined by Gannet BioChem’s board of directors. As of December 31, 2025, Gannet BioChem has issued 8.4 million stock appreciation rights, which have a $1.00 base value.

In the event of a distribution, to the extent available, the preferred unitholders have priority rights to a cumulative preferred dividend at a certain annual rate of return and a return of their investment before any distributions to common unitholders. After such priority distribution to the preferred unitholders, to the extent available, common unitholders are to receive a distribution of both a cumulative dividend at the same rate as the preferred unitholders’ dividend and a return of their investment, which, for our common units, is equal to $20.0 million (or $1.00 per unit). Any distributions in excess of both of these distributions, if available, are distributed to preferred and common unitholders pro rata.

We have significant influence, but do not control, Gannet BioChem through our noncontrolling representation on Gannet BioChem’s board of directors and our equity interests in Gannet BioChem. Accordingly, we do not consolidate Gannet BioChem and account for our investment in Gannet BioChem using the equity method of accounting. We record our share of Gannet BioChem’s gains and losses under the HLBV basis, which reflects Ampersand’s liquidation preferences as described above. The HLBV method is a balance sheet approach that calculates the change in the hypothetical amount we and Ampersand would be entitled to receive if Gannet BioChem were liquidated at book value, adjusted for any contributions made and distributions received during the period, as well as basis differences between the initial fair value of our investment

in Gannet BioChem and our claim on the net assets of Gannet BioChem. Our loss from our investment in Gannet BioChem for the twelve months ended December 31, 2025 is as follows (in thousands):


	Year Ended December 31, 2025
Claim on net assets of Gannet BioChem - beginning of period	$	12,218
Claim on net assets of Gannet BioChem - end of period		3,491
Change in claim on net assets of Gannet BioChem	$	(8,727	)

Gannet BioChem is considered a related party to Nektar. Concurrently with the closing of the transaction, we entered into certain ancillary agreements with Gannet BioChem, including supply agreements for rezpegaldesleukin and NKTR-255, and certain services agreements.

Supply Agreements

Under the terms of the supply agreements, Gannet BioChem has agreed to manufacture and supply the PEG reagents for use in clinical trials of these drug candidates at prices defined within the agreements. There are no minimum purchase commitments and Nektar can terminate the agreement for convenience upon prior written notice. For the twelve months ended December 31, 2025, we recorded $0.7 million as research and development expense for services provided by Gannet BioChem to us in our Consolidated Statements of Operations under the supply agreements.

Services Agreements

Pursuant to a transition services agreement and full-time employee equivalent agreement, Nektar is performing certain transition services for the benefit of Gannet BioChem, primarily related to information technology and accounting, and Gannet BioChem is performing certain services for the benefit of Nektar, primarily to support research and development activities. The terms of these agreements are no more than two years, subject to certain termination provisions. For the twelve months ended December 31, 2025, we recorded $1.9 million as research and development expense for services provided by Gannet BioChem to us in our Consolidated Statements of Operations. For the twelve months ended December 31, 2025, we recorded $1.1 million as other income in our Consolidated Statements of Operations for services provided by us to Gannet BioChem.

As of December 31, 2025, we recorded a net receivable of $0.4 million from Gannet BioChem and payables of $1.1 million to Gannet BioChem, consisting of amounts billable under the services agreements. We report the net receivable in other current asset and the payables in accounts payable and accrued expenses, respectively, in our Consolidated Balance Sheets.

Income Taxes

12 Months Ended

Dec. 31, 2025

Income Tax Disclosure [Abstract]

Income Taxes

Note 13 — Income Taxes

Loss before benefit for income taxes includes the following components (in thousands):


	Year Ended December 31,
	2025			2024
Domestic	$	(164,576	)	$	(119,227	)
Foreign		362			27
Loss before benefit for income taxes	$	(164,214	)	$	(119,200	)

Benefit for Income Taxes

The benefit for income taxes consists of the following (in thousands):


	Year Ended December 31,
	2025			2024
Current:
Federal	$	—		$	—
State		8			(277	)
Foreign		(210	)		48
Total current income tax benefit		(202	)		(229	)
Deferred:
Federal		—			—
State		—			—
Foreign		64			(10	)
Total deferred income tax expense		64			(10	)
Benefit for income taxes	$	(138	)	$	(239	)

As discussed in Note 1, we adopted ASU 2023-09 on a prospective basis beginning with the year ended December 31, 2025. The following table presents the reconciliation of our U.S. federal statutory tax amount and rate to our effective amount and rate for the year ended December 31, 2025 (dollars in thousands):


	Year Ended December 31, 2025
	Amount			Percent
U.S. Federal Statutory Tax Rate	$	(34,485	)		21.0	%
State & local income taxes, net of federal income tax effect		8			0.0	%
Foreign tax effects		(295	)		0.2	%
Effects of changes in tax laws or rates enacted in the current period		—			0.0	%
Effects of cross-border tax laws		—			0.0	%
Research credits		(781	)		0.5	%
Changes in valuation allowances		6,913			(4.2	)%
Nontaxable or nondeductible items
Stock-based compensation		6,881			(4.2	)%
Liabilities related to the sales of future royalties, net		(4,085	)		2.5	%
Other		1,266			(0.8	)%
Changes in unrecognized tax benefits		(431	)		0.3	%
Other adjustments
Expiration of net operating loss carryforwards		24,806			(15.2	)%
Other		65			0.0	%
Benefit for income taxes	$	(138	)		0.1	%

The Company’s effective tax rate differs from the U.S. federal statutory rate primarily due to tax credits, changes in valuation allowances, and nondeductible expenses. The rate was reduced by federal and state research and development credits generated during the year and by adjustments to prior-year credit carryforwards. Our tax payments were immaterial.


	Year Ended December 31,
	2024
Income tax benefit at federal statutory rate	$	(25,032	)
Research credits		7,741
Change in valuation allowance		1,635
Expiration of net operating loss carryforwards		8,252
Stock-based compensation		4,280
Non-cash interest expense on liabilities related to sales of future royalties		5,904
Non-cash royalty revenue related to sales of future royalties		(5,645	)
Impairment of goodwill		—
Other		2,626
Benefit for income taxes	$	(239	)

Effective Tax Rate		0.20	%

Deferred Tax Assets and Liabilities

Deferred income taxes reflect the net tax effects of loss and credit carryforwards and temporary differences between the carrying amount of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. We measure deferred tax assets and liabilities based on the rates at which they are expected to reverse in the future. Significant components of our deferred tax assets for federal and state income taxes are as follows (in thousands):


	December 31,
	2025			2024
Deferred tax assets:
Net operating loss carryforwards	$	625,497		$	587,528
Research and other credits		137,530			135,871
Net capital loss carryforwards		39,648			39,648
Operating lease liabilities		24,517			22,767
Stock-based compensation		18,277			19,619
Capitalized research and development costs		35,183			45,607
Liabilities related to the sales of future royalties		—			2,020
Other		12,830			9,402
Deferred tax assets before valuation allowance		893,482			862,462
Valuation allowance for deferred tax assets		(892,432	)		(859,084	)
Total deferred tax assets		1,050			3,378
Deferred tax liabilities:
Investment in foreign subsidiary		(575	)		(511	)
Other		(1,050	)		(3,377	)
Total deferred tax liabilities		(1,625	)		(3,888	)
Net deferred tax assets (liabilities)	$	(575	)	$	(510	)

Realization of our deferred tax assets is dependent upon future earnings, if any, the timing and amount of which are uncertain. Because of our lack of U.S. earnings history and projected future losses, we have fully reserved our net U.S. deferred tax assets with a valuation allowance. The valuation allowance increased by $33.3 million for the year ended December 31, 2025 and increased by $4.6 million for the year ended December 31, 2024.

Our net deferred tax liability position reflects the provision for the withholding taxes associated with the repatriation of accumulated earnings and profits from India.

Net Operating Loss and Tax Credit Carryforwards

As of December 31, 2025, we had a net operating loss carryforward for federal income tax purposes of approximately $2.9 billion, of which $1.1 billion is subject to expiration beginning in 2026 and a total state net operating loss carryforward of approximately $1.0 billion, portions of which will begin to expire in 2027. We have federal tax credits of approximately $127.6 million, which will begin to expire in 2026 and state research credits of approximately $61.4 million which have no expiration date. Utilization of some of the federal and state net operating loss and credit carryforwards are subject to annual limitations due to the “change in ownership” provisions of the Internal Revenue Code of 1986 and similar state provisions.

Unrecognized tax benefits

We have the following activity relating to unrecognized tax benefits (in thousands):


	Year Ended December 31,
	2025			2024
Beginning balance	$	135,672		$	126,498
Tax positions related to current year:
Additions		704			582
Reductions		—			—
Tax positions related to prior years:
Additions		27			10,101
Reductions		(9	)		(16	)
Settlements		—			(815	)
Lapses in statute of limitations		(459	)		(678	)
Ending balance	$	135,935		$	135,672

We currently have a full valuation allowance against our U.S. net deferred tax asset which would impact the timing of the effective tax rate benefit should any of these uncertain tax positions be favorably settled in the future. Adjustments to the substantial majority of our uncertain tax positions would result in an adjustment of our net operating loss or tax credit carryforwards rather than resulting in a cash outlay.

We file income tax returns in the U.S., California, Alabama, certain other states and India and certain other international jurisdictions. As a result of our net operating loss and research credit carryforwards, substantially all of our domestic tax years remain open and subject to examination. We may be subject to examination in India and other jurisdictions from time to time. Pursuant to a review of an India income tax return, in January 2026, we received a demand in India, which we are in the process of appealing. We have assessed the merits of the demand and have not recorded a provision as we believe that it is more likely than not that we will prevail. We do not believe that any liability resulting from such this or other examination would have a material effect on our financial position or results of operations.

Our policy is to include interest and penalties related to unrecognized tax benefits, if any, within the benefit for income taxes in the consolidated statements of operations. During the years ended December 31, 2025 and 2024, no significant interest or penalties were recognized relating to unrecognized tax benefits.

The entire disclosure for income tax.

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CONSOLIDATED STATEMENTS OF OPERATIONS (Parenthetical)
$ in Thousands

12 Months Ended

Dec. 31, 2025

USD ($)

Dec. 31, 2024

USD ($)

Research and development

$ 117,330

$ 120,908

^[1]

$ 361

$ (390)

^[1]

0.07

Reverse stock split

one-for-fifteen reverse stock split

Related Party

Research and development

$ 2,636

$ 277