As filed with the Securities and Exchange Commission on August 7, 2020

Registration No. 333-            

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM S-8

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

NEKTAR THERAPEUTICS

(Exact name of registrant as specified in its charter)

455 Mission Bay Boulevard South

San Francisco, California 94158

(Address of Principal Executive Offices and Zip Code)

Nektar Therapeutics Amended and Restated 2017 Performance Incentive Plan

Nektar Therapeutics Amended and Restated Employee Stock Purchase Plan

(Full Title of the Plan)

Mark A. Wilson

Senior Vice President and General Counsel

Nektar Therapeutics

455 Mission Bay Boulevard South

San Francisco, California 94158

415-482-5300

(Name, Address, and Telephone Number, Including Area Code, of Agent for Service)

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act.  ☐

Calculation of Registration Fee

EXPLANATORY NOTE

On March 31, 2020, the board of directors of the Registrant approved an amendment to Registrant’s Amended and Restated 2017 Performance Incentive Plan (as amended, the “PIP”), pursuant to which the number of shares of Common Stock reserved and available for issuance under the PIP increased by 10,000,000 shares subject to stockholder approval, which was received on June 17, 2020. This Registration Statement on Form S-8 registers these 10,000,000 additional shares of Common Stock. The additional shares available for issuance under the PIP are of the same class as other securities relating to the PIP for which the Registrant’s registration statements filed on Form S-8 (Registration No. 333-218777) on June 15, 2017, and on Form S-8 (Registration No. 333-226004) on June 29, 2018, are effective.

On March 31, 2020, the board of directors of the Registrant also approved an amendment and restatement of the Registrant’s Amended and Restated Employee Stock Purchase Plan (the “ESPP”), pursuant to which the number of shares of Common Stock reserved and available for issuance under the ESPP increased by 1,000,000 shares subject to stockholder approval, which was received on June 17, 2020. The additional shares available for issuance under the ESPP are of the same class as other securities relating to the ESPP for which the Registrant’s registration statements filed on Form S-8 (File No. 33-79630) on June 1, 1994, on Form S-8 (File No. 333-98321) on August 19, 2002, on Form S-8 (Registration No. 333-170371) on November 4, 2010, and on Form S-8 (Registration No. 333-197781) on August 1, 2014, are effective.

The information contained in the Registrant’s prior registration statements on Form S-8 is hereby incorporated by reference pursuant to General Instruction E, except for “Item 8. Exhibits.”

PART II

INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

SIGNATURES

Pursuant to the requirements of the Securities Act, the Company certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of San Francisco, State of California, on August 7, 2020.

POWER OF ATTORNEY

Each person whose signature appears below constitutes and appoints Howard W. Robin and Gil M. Labrucherie, and each of them, acting individually and without the other, as his or her true and lawful attorneys-in-fact and agents, with full power of substitution and resubstitution, for him or her and in his or her name, place, and stead, in any and all capacities, to sign any and all amendments (including post-effective amendments, exhibits thereto, and other documents in connection therewith) to this Registration Statement, and to file the same, with all exhibits thereto, and other documents in connection therewith, with the Commission, granting unto said attorneys-in-fact and agents, and each of them, full power and authority to do and to perform each and every act and thing requisite and necessary to be done in and about the premises, as fully to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that said attorneys-in-fact and agents, or either of them individually, or their, his or her substitute or substitutes, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act, this Registration Statement has been signed by the following persons in the capacities and on the dates indicated.

Exhibit 5.1

August 7, 2020

Nektar Therapeutics

455 Mission Bay Boulevard South

San Francisco, California 94158

We have acted as counsel to you in connection with your filing of a Registration Statement on Form S-8 (the “Registration Statement”) pursuant to the Securities Act of 1933, as amended (the “Securities Act”), on or about the date hereof relating to an aggregate of 11,000,000 shares (the “Shares”) of Common Stock, $0.0001 par value per share (“Common Stock”), of Nektar Therapeutics, a Delaware corporation (the “Company”), that may be issued pursuant to the Company’s Amended and Restated 2017 Performance Incentive Plan and Amended and Restated Employee Stock Purchase Plan (collectively, the “Plans”).

We have reviewed such documents and made such examination of law as we have deemed appropriate to give the opinions set forth below. We have relied, without independent verification, on certificates of public officials and, as to matters of fact material to the opinion set forth below, on certificates of officers of the Company.

The opinion set forth below is limited to the Delaware General Corporation Law.

For purposes of the opinion set forth below, we have assumed that no event occurs that causes the number of authorized shares of Common Stock available for issuance by the Company to be less than the number of then unissued Shares.

Based on the foregoing, we are of the opinion that the Shares have been duly authorized and, upon issuance and delivery against payment therefor in accordance with the terms of the Plans, will be validly issued, fully paid and nonassessable.

We hereby consent to the inclusion of this opinion as Exhibit 5.1 to the Registration Statement. In giving our consent, we do not admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations thereunder.

Exhibit 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We consent to the incorporation by reference in the Registration Statement (Form S-8) pertaining to the Nektar Therapeutics Amended and Restated 2017 Performance Incentive Plan and the Nektar Therapeutics Amended and Restated Employee Stock Purchase Plan of our reports dated February 27, 2020, with respect to the consolidated financial statements of Nektar Therapeutics and the effectiveness of internal control over financial reporting of Nektar Therapeutics included in its Annual Report (Form 10-K) for the year ended December 31, 2019, filed with the Securities and Exchange Commission.

/s/ Ernst & Young LLP

Redwood City, California

August 7, 2020