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As filed with the Securities and Exchange Commission on December 6, 2004

Registration No. 333-120009

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

Amendment No. 1
to
FORM S-3
REGISTRATION STATEMENT
UNDER
THE SECURITIES ACT OF 1933

Nektar Therapeutics
(Exact name of registrant as specified in its charter)

Delaware
(State or Other Jurisdiction of
Incorporation or Organization)		   94-3134940
(I.R.S. Employer
Identification Number)

Industrial Road
San Carlos, CA 94070
(650) 631-3100
(Address, including zip code, and telephone number, including area code, of Registrant's principal executive offices)

Ajit S. Gill
President, Chief Executive Officer and Director
Nektar Therapeutics
150 Industrial Road
San Carlos, CA 94070
(650) 631-3100
(Name, address, including zip code, and telephone number, including area code, of agent for services)

Copies to:

Mark P. Tanoury, Esq.
John M. Geschke, Esq.
Cooley Godward LLP
Five Palo Alto Square
3000 El Camino Real
Palo Alto, CA 94306-2155
(650) 843-5000

Approximate date of commencement of proposed sale to the public:
From time to time after the effective date of this registration statement.

       If the only securities being registered on this form are being offered pursuant to dividend or interest reinvestment plans, please check the following box. o

       If any of the securities being registered on this form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, other than securities offered only in connection with dividend or interest reinvestment plans, check the following box. ý

       If this form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. o

       If this form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. o

       If delivery of the prospectus is expected to be made pursuant to Rule 434, please check the following box. o

CALCULATION OF REGISTRATION FEE

Title of Each Class of Securities To Be Registered(1)
   Proposed Maximum
Aggregate
Offering
Price(2)
   Amount of
Registration Fee(3)
Common Stock, par value $0.0001 per share(4)   —   —
Preferred Stock, par value $0.0001 per share   —   —
Warrants   —   —
Debt Securities   —   —
Total   $250,000,000   $31,675(5)
(1)
The registrant is filing this registration statement under rule 429 of the Securities Act. There are being registered hereunder such indeterminate number of shares of common stock and preferred stock, such indeterminate number of warrants to purchase common stock, preferred stock or debt securities and such indeterminate principal amount of debt securities as shall have an aggregate initial offering price not to exceed $250,000,000. If any debt securities are issued at an original issued discount, then the offering price of such debt securities shall be in such greater principal amount as shall result in an aggregate initial offering price not to exceed $250,000,000, less the aggregate dollar amount of all securities previously issued hereunder. Any securities registered hereunder may be sold separately or as units with other securities registered hereunder. The securities registered also include such indeterminate amounts and numbers of common stock, preferred stock and debt securities as may be issued upon conversion or redemption of or exchange for preferred stock or debt securities that provide for conversion, redemption or exchange, upon exercise of warrants or pursuant to the antidilution provisions of any such securities. Of the securities described above, $50,500,000 of these securities (the "Prior Securities") have already been registered pursuant to a Registration Statement on Form S-3 (File No. 333-108859) initially filed on September 17, 2003 and declared effective by the Securities and Exchange Commission on September 29, 2003 (the "Original Registration Statement").

(2)
The proposed maximum aggregate offering price per class of security will be determined from time to time by the registrant in connection with the issuance by the registrant of the securities registered hereunder and is not specified as to each class of security pursuant to General Instruction II.D of Form S-3 under the Securities Act.

(3)
Calculated pursuant to Rule 457(o) under the Securities Act. The registrant previously paid a fee of $4,085 covering the Prior Securities in connection with the filing of the Original Registration Statement which shall offset the currently due filing fee as permitted by Rule 457(p) under the Securities Act. The registrant shall pay an additional filing fee of $27,590 at the time of filing of this registration statement in connection with the registration of securities with a value of $199,500,000.

(4)
Each share of the registrant's common stock being registered hereunder, if issued prior to the termination by the registrant of its preferred share rights agreement, includes Series A junior participating preferred stock purchase rights. Prior to the occurrence of certain events, the Series A junior participating preferred stock purchase rights will not be exercisable or evidenced separately from the registrant's common stock and have no value except as reflected in the market price of the shares to which they are attached.

(5)
$31,675 was previously paid and no fee is included with this filing.

       The registrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date until the registrant shall file a further amendment which specifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933 or until the registration statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a), may determine.

       The registrant is filing this registration statement under Rule 429 of the Securities Act of 1933. The combined prospectus contained herein also relates to securities previously registered under a registration statement on Form S-3 with file number 333-108859.

The information in this prospectus is not complete and may be changed. We may not sell these securities or accept an offer to buy these securities until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities and we are not soliciting an offer to buy these securities in any state where the offer or sale is not permitted.

Subject To Completion, Dated December 6, 2004

PROSPECTUS

NEKTAR THERAPEUTICS

$250,000,000

Common Stock
Preferred Stock
Debt Securities
Warrants

        From time to time, we may sell common stock, preferred stock, debt securities and/or warrants.

        We will provide the specific terms of these securities in one or more supplements to this prospectus. You should read this prospectus and any prospectus supplement carefully before you invest.

        Our common stock currently trades on The Nasdaq National Market under the symbol "NKTR." The applicable prospectus supplement will contain information, where applicable, as to any other listing (if any) on The Nasdaq National Market or any securities exchange of the securities covered by the prospectus supplement.

        This prospectus may not be used to offer or sell any securities unless accompanied by a prospectus supplement.

        Investing in our securities involves a high degree of risk. Please see the section entitled "Risk Factors" beginning on page 23 of our most recent quarterly report on Form 10-Q, as filed with the Securities and Exchange Commission, which is incorporated by reference herein in its entirety.

        The securities may be sold directly by us to investors, through agents designated from time to time or to or through underwriters or dealers. For additional information on the methods of sale, you should refer to the section entitled "Plan of Distribution." If any underwriters are involved in the sale of any securities with respect to which this prospectus is being delivered, the names of such underwriters and any applicable commissions or discounts will be set forth in a prospectus supplement. The net proceeds we expect to receive from such sale will also be set forth in a prospectus supplement.

        Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus is                        , 2004


TABLE OF CONTENTS

 
   Page
ABOUT THIS PROSPECTUS   3
NEKTAR THERAPEUTICS   4
RISK FACTORS   5
FORWARD-LOOKING STATEMENTS   5
THE SECURITIES WE MAY OFFER   6
RATIO OF EARNINGS TO FIXED CHARGES   7
USE OF PROCEEDS   9
DESCRIPTION OF CAPITAL STOCK   9
DESCRIPTION OF DEBT SECURITIES   15
DESCRIPTION OF WARRANTS   22
LEGAL OWNERSHIP OF SECURITIES   23
PLAN OF DISTRIBUTION   27
LEGAL MATTERS   28
EXPERTS   28
WHERE YOU CAN FIND MORE INFORMATION   28

        This prospectus contains summaries of certain provisions contained in some of the documents described herein, but reference is made to the actual documents for complete information. All of the summaries are qualified in their entirety by the actual documents. Copies of some of the documents referred to herein have been filed, will be filed or incorporated by reference as exhibits to the registration statement of which this prospectus is a part, and you may obtain copies of those documents as described below under "Where You Can Find More Information."

        This prospectus is part of a registration statement we filed with the Securities and Exchange Commission (the "SEC"). You should rely only on the information we have provided or incorporated by reference in this prospectus or any prospectus supplement. We have not authorized anyone to provide you with information different from that contained in this prospectus. No dealer, salesperson or other person is authorized to give any information or to represent anything not contained in this prospectus. You must not rely on any unauthorized information or representation. This prospectus is an offer to sell only the securities offered hereby, but only under circumstances and in jurisdictions where it is lawful to do so. You should assume that the information in this prospectus or any prospectus supplement is accurate only as of the date on the front of the document and that any information we have incorporated by reference is accurate only as of the date of the document incorporated by reference, regardless of the time of delivery of this prospectus or any sale of a security.


ABOUT THIS PROSPECTUS

        This prospectus is part of a registration statement that we filed with the SEC using a "shelf" registration process. Under this shelf registration process, we may sell common stock, preferred stock, debt securities and/or warrants in one or more offerings up to a total dollar amount of $250,000,000. This prospectus provides you with a general description of the securities we may offer. Each time we sell common stock, preferred stock, debt securities and/or warrants, we will provide a prospectus supplement that will contain more specific information, as set forth below in the section entitled "The Securities We May Offer." We may also add, update or change in the prospectus supplement any of the information contained in this prospectus. Please carefully read both this prospectus and any prospectus supplement together with the additional information described below under "Where You Can Find More Information." This prospectus may not be used to consummate a sale of securities unless it is accompanied by a prospectus supplement.

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NEKTAR THERAPEUTICS

        Nektar Therapeutics is in the business of improving therapeutics through improved drug delivery. Each of our three technology platforms has the ability to transform therapeutics with differentiating properties based on the technology and the particular application of the technology.

        We are working to become one of the world's leading drug delivery products based companies by providing a portfolio of technologies and expertise that will enable us and our pharmaceutical and biotechnology partners to improve drug performance throughout the drug development process.

        Our mission is to provide drug delivery technologies that enable the development and manufacture of superior therapeutics that make a difference in patients' lives. We partner with pharmaceutical and biotechnology companies seeking to improve and differentiate their marketed products as well as the products in their pipelines. In addition to our partner-funded programs, we are applying our technologies independently through internal product development efforts.

        Our technologies are designed to improve either the performance of a drug molecule (e.g., bioavailability, safety, efficacy, stability, targeting, etc.) or how the drug is delivered (e.g., enabling new dosage form or delivery profile that improves how the therapeutic can treat patients).

        We currently have three technology platforms:

        Our strategy is to enable our partners' drugs through partner-funded programs, and to selectively fund internal proprietary products. As we identify the technologies and markets in which we see opportunities to establish leadership positions, we intend to continue to develop or acquire technologies to capitalize on such opportunities.

        We currently have collaborations ongoing with more than 20 biotechnology and pharmaceutical companies. Our product pipeline includes 5 products approved in the United States, 1 additional product approved in Europe, 1 product which has been filed with the EMEA in Europe, 1 additional product that has been filed with the FDA in the U.S. and with the EMEA in Europe, 4 products in Phase III trials, and over 10 products in Phase I and Phase II trials.

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        Our principal executive offices are located at 150 Industrial Road, San Carlos, California 94070. Our telephone number is (650) 631-3100. We maintain an Internet home page at www.nektar.com. The contents of our web page are not a part of this prospectus.

        All Nektar brand and product names are trademarks or registered trademarks of Nektar Therapeutics, in the United States and other countries. All other trade names, trademarks and service marks appearing in this prospectus are the property of their respective holders. We do not intend our use or display of other parties' trade names, or trademarks or service marks to imply a relationship with, or endorsement or sponsorship of, us by these other parties.


RISK FACTORS

        Except for the historical information contained in this prospectus or incorporated by reference, this prospectus (and the information incorporated by reference in this prospectus) contains forward-looking statements that involve risks and uncertainties. Our actual results could differ materially from those discussed here or incorporated by reference. Factors that could cause or contribute to such differences include, but are not limited to, those discussed in the section entitled "Risk Factors" beginning on page 23 of our most recent quarterly report on Form 10-Q filed with the SEC, which is incorporated herein by reference in its entirety.

        Investment in our securities involves a high degree of risk. You should consider carefully the Risk Factors, as well as other information in this prospectus and the prospectus supplement before purchasing any of our securities. Each of these factors could adversely affect our business, operating results and financial condition, as well as adversely affect the value of an investment in our securities.


FORWARD-LOOKING STATEMENTS

        This prospectus and the documents that we have filed with the SEC that are included or incorporated or deemed to be incorporated by reference in this prospectus include "forward-looking statements" within the meaning of Section 27A of the Securities Act and Section 21E of the Securities Exchange Act of 1934. You can identify these statements by the fact that they do not relate strictly to historical or current facts. Such statements may include words such as "anticipate," "estimate," "expect," "project," "intend," "plan," "believe" and other words and terms of similar meaning in connection with any discussion of future operating or financial performance. In particular, these statements include, among other things, statements relating to:

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        Any or all of our forward-looking statements in this prospectus and in the documents incorporated or deemed to be incorporated by reference in this prospectus may turn out to be wrong. They can be affected by inaccurate assumptions we might make or by known or unknown risks and uncertainties. Many factors mentioned in our discussion in this prospectus will be important in determining future results. Consequently, no forward-looking statement can be guaranteed. Actual future results may vary materially.

        We undertake no obligation to publicly update any forward-looking statements, whether as a result of new information, future events or otherwise. We advise you to consult any additional cautionary discussion of risks and uncertainties under "Risk Factors" beginning on page 23 of our most recent quarterly report on Form 10-Q. These are factors that we think are the most significant risks that could cause our actual results to differ materially from expected results. Other factors besides those listed herein or in our most recent quarterly report on Form 10-Q could also adversely affect us. This discussion is provided as permitted by the Private Securities Litigation Reform Act of 1995.


THE SECURITIES WE MAY OFFER

        We may offer shares of our common stock and preferred stock, various series of debt securities and/or warrants to purchase any of such securities with a total value of up to $250,000,000 from time to time under this prospectus at prices and on terms to be determined by market conditions at the time of offering. This prospectus provides you with a general description of the securities we may offer. Each time we offer a type or series of securities, we will provide a prospectus supplement that will describe the specific amounts, prices and other important terms of the securities, including, to the extent applicable:

        The prospectus supplement also may add, update or change information contained in this prospectus or in documents we have incorporated by reference.

        We may sell the securities directly to or through agents, underwriters or dealers. We, and our agents or underwriters, reserve the right to accept or reject all or part of any proposed purchase of securities. If we do offer securities through agents or underwriters, we will include in the applicable prospectus supplement:

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        Common Stock.    We may issue shares of our common stock from time to time. Holders of common stock are entitled to one vote per share on all matters submitted to a vote of stockholders. Subject to any preferences of outstanding shares of preferred stock, holders of common stock are entitled to dividends when and if declared by our board of directors.

        Preferred Stock.    We may issue shares of our preferred stock from time to time, in one or more series. Our board of directors shall determine the rights, preferences, privileges and restrictions of the preferred stock, including dividend rights, conversion rights, voting rights, terms of redemption, liquidation preferences, sinking fund terms and the number of shares constituting any series or the designation of any series. Convertible preferred stock will be convertible into our common stock. Conversion may be mandatory or at your option and would be at prescribed conversion rates.

        Debt Securities.    We may offer debt securities from time to time, in one or more series, as either senior or subordinated debt or as senior or subordinated convertible debt. The senior debt securities will rank equally with any other unsecured and unsubordinated debt. The subordinated debt securities will be subordinate and junior in right of payment, to the extent and in the manner described in the instrument governing the debt, to all of our senior indebtedness. Convertible debt securities will be convertible into or exchangeable for our common stock or our other securities. Conversion may be mandatory or at your option and would be at prescribed conversion rates.

        The debt securities will be issued under one or more documents called indentures, which are contracts between us and a national banking association, as trustee. In this prospectus, we have summarized certain general features of the debt securities. We urge you, however, to read the prospectus supplements related to the series of debt securities being offered, as well as the complete indentures that contain the terms of the debt securities. Indentures have been filed as exhibits to the registration statement of which this prospectus is a part, and supplemental indentures and forms of debt securities containing the terms of debt securities being offered will be filed as exhibits to the registration statement of which this prospectus is a part or will be incorporated by reference from reports we file with the SEC.

        Warrants.    We may issue warrants for the purchase of common stock, preferred stock and/or debt securities in one or more series. We may issue warrants independently or together with common stock, preferred stock and/or debt securities, and the warrants may be attached to or separate from these securities. In this prospectus, we have summarized certain general features of the warrants. We urge you, however, to read the prospectus supplements related to the series of warrants being offered, as well as any warrant agreement that contains the terms of the warrants. The warrant agreement and form of warrant containing the terms of the warrants being offered will be filed as exhibits to the registration statement of which this prospectus is a part or will be incorporated by reference from reports we file with the SEC. We will evidence each series of warrants by warrant certificates that we will issue under a separate agreement. We will enter into the warrant agreement with a warrant agent. Each warrant agent will be a bank that we select which has its principal office in the United States and a combined capital and surplus of at least $50,000,000. We will indicate the name and address of the warrant agent in the applicable prospectus supplement relating to a particular series of warrants.


RATIO OF EARNINGS TO FIXED CHARGES

        Our earnings were insufficient to cover fixed charges in each of the years in the five-year period ended December 31, 2003 and in the nine-month periods ended September 30, 2004 and 2003. Earnings consist of loss from continuing operations before income taxes, extraordinary items, cumulative effect of accounting changes, equity in net losses of affiliates and fixed charges, adjusted for capitalized interest. Fixed charges consist of interest expensed and capitalized and amortized premiums, discounts and capitalized expenses related to indebtedness. Preference dividends are the amount of

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pre-tax earnings that is required to pay the dividends on outstanding preference securities. The extent to which earnings were insufficient to cover fixed charges is as follows:

 
   Year Ended December 31,
   Nine Months Ended
September 30,
  
 
   2003
   2002
   2001
   2000
   1999
   2004
   2003
  
 
   (in thousands)

  
Deficiency of earnings available to cover fixed charges   $ (65,721 ) $ (107,468 ) $ (251,238 ) $ (97,403 ) $ (38,448 ) $ (82,484 ) $ (50,194 )
Ratio of earnings to fixed charges     N/A     N/A     N/A     N/A     N/A     N/A     N/A  
Ratio of fixed charges and preference dividends to earnings     N/A     N/A     N/A     N/A     N/A     N/A     N/A  

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USE OF PROCEEDS

        Except as described in any prospectus supplement, we currently intend to use the net proceeds from the sale of our securities for general corporate purposes, which may include:

        We intend to increase our investments in our proprietary product programs and may expand the technology platforms important to the development of our business through our internal efforts and through technology acquisitions. We evaluate acquisitions on a regular basis. A substantial amount of the net proceeds of this offering may be utilized to fund these acquisitions, although we currently are not planning or negotiating any such transactions. However, we cannot assure you that we will be able to complete acquisitions on an advantageous basis or at all. Pending these uses, the net proceeds will be invested in investment-grade, interest-bearing securities.


DESCRIPTION OF CAPITAL STOCK

        The following description of our capital stock and certain provisions of our certificate of incorporation, bylaws and share purchase rights plan, is a summary and is qualified in its entirety by the provisions of our certificate of incorporation, bylaws and share purchase rights plan.

        Our authorized capital stock consists of 300,000,000 shares of common stock, $0.0001 par value, and 10,000,000 shares of preferred stock, $0.0001 par value, of which 3,100,000 shares have been designated Series A junior participating preferred stock and 40,000 shares have been designated Series B convertible preferred stock. As of October 29, 2004, there were 83,966,223 shares of common stock outstanding, no shares of Series A junior participating preferred stock and 19,945 shares of Series B convertible preferred stock outstanding.

Common Stock

        The holders of common stock are entitled to one vote for each share held of record on all matters submitted to a vote of the stockholders. The holders of common stock are not entitled to cumulative voting rights with respect to the election of directors, and as a consequence, minority stockholders are not able to elect directors on the basis of their votes alone. Subject to preferences that may be applicable to any shares of preferred stock currently outstanding or issued in the future, holders of common stock are entitled to receive ratably such dividends as may be declared by our board of directors out of funds legally available therefor. In the event of our liquidation, dissolution or winding up, holders of our common stock are entitled to share ratably in all assets remaining after payment of liabilities and the liquidation preference of any then outstanding preferred stock. Holders of common stock have no preemptive rights and no right to convert their common stock into any other securities. There are no redemption or sinking fund provisions applicable to the common stock. All shares of common stock that may be issued under this prospectus will be, fully paid and non-assessable.

Preferred Stock

        Of the 10,000,000 shares of preferred stock authorized, we have designated 3,100,000 shares as Series A junior participating preferred stock and 40,000 shares as Series B convertible preferred stock. Our board of directors has the authority, without further vote or action by the stockholders, to issue up to 6,860,000 shares of preferred stock in one or more series and to fix the rights, preferences, privileges and restrictions thereof, including dividend rights, conversion rights, voting rights, terms of redemption,

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liquidation preferences, sinking fund terms and the number of shares constituting any series or the designation of such series. The issuance of preferred stock could adversely affect the voting power or other rights of holders of common stock and the likelihood that such holders will receive dividend payments and payments upon liquidation and could have the effect of delaying, deferring or preventing a change in control.

Series A Junior Participating Preferred Stock

        In June 2001, our board of directors approved the adoption of a share purchase rights plan and, pursuant to its authority as described above, authorized 3,100,000 shares of Series A junior participating preferred stock. A certificate of designation filed with the Secretary of State of the State of Delaware sets forth the rights, privileges and preferences of the Series A junior participating preferred stock. Terms of the share purchase rights plan provide for a dividend distribution of one preferred share purchase right for each outstanding share of our common stock. The rights have certain anti-takeover effects and will cause substantial dilution to a person or group that attempts to acquire us on terms not approved by our board of directors. The dividend distribution was payable on June 22, 2001 to stockholders of record on that date. We have issued one right for each share of Common Stock we issued subsequent to such date and, until expiration of the rights plan or any earlier redemption or exchange of rights by us or the occurrence of a "distribution date" as described below, we will issue one right in respect of each share of common stock we issue in the future. Each right entitles the registered holder to purchase from us 1/100 of a share of Series A junior participating preferred stock at a price of $225.00 per 1/100 of a share of Series A junior participating preferred stock, subject to adjustment. Each 1/100 of a share of Series A junior participating preferred stock has designations and powers, preferences and rights, and the qualifications, limitations and restrictions which make its value approximately equal to the value of a share of common stock.

        The rights are not exercisable until the "distribution date" as defined in the certificate of designation for the Series A junior participating preferred stock and, until that date, the rights will trade with the common stock and will be evidenced solely by the common stock certificates. The rights will expire on June 1, 2011, unless the rights are earlier redeemed (at a redemption price of $0.001 per right) or exchanged by us. Each share of Series A junior participating preferred stock will be entitled to a quarterly dividend payment in preference to the common stock equal to the greater of $1.00 and 100 times the dividend declared per share of common stock. In the event of liquidation, dissolution or winding up of us, the holders of the Series A junior participating preferred stock would be entitled to a liquidation payment in preference to the common stock of the greater of $100 per share and 100 times the payment made per share of common stock. Each share of Series A junior participating preferred stock will have 100 votes on all matters submitted to a vote of the stockholders, voting together with the common stock. Finally, in the event of any merger, consolidation, combination or other transaction in which the shares of common stock are exchanged into other stock or securities, cash and/or any other property, each share of Series A junior participating preferred stock will be entitled to receive 100 times the aggregate amount of stock, securities, cash and/or other property into which a share of common stock is exchanged. Because of the nature of the Series A junior participating preferred stock dividend and liquidation rights, the value of 1/100 of a share of Series A junior participating preferred stock should approximate the value of one share of common stock. The Series A junior participating preferred stock ranks junior to the Series B convertible preferred stock and would rank junior to any other series of preferred stock. Until a right is exercised, the holder thereof, as such, will have no rights as a stockholder, including, without limitation, the right to vote or to receive dividends.

        See, "Anti-Takeover Effects of Provisions of Delaware Law and Our Charter Documents" below for a further description of some of the terms of the rights plan.

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Series B Convertible Preferred Stock

        In January 2002, our board of directors, pursuant to its authority as described above, authorized 40,000 shares of Series B convertible preferred stock. In connection with a strategic alliance with Enzon Pharmaceuticals, Inc., we entered into a preferred stock purchase agreement pursuant to which we sold to Enzon and Enzon purchased from us 40,000 shares of non-voting Series B convertible preferred stock at a purchase price of $1,000 per share for an aggregate purchase price of $40,000,000. In February and March of 2004, Enzon converted a total of 20,055 shares of Series B convertible preferred stock into 880,085 shares of common stock and as of September 30, 2004 there were 19,945 shares of Series B preferred stock outstanding. A certificate of designation filed with the Secretary of State of the State of Delaware sets forth the rights, privileges and preferences of the Series B convertible preferred stock. Pursuant to the certificate of designation, the Series B convertible preferred stock does not have voting rights except as required by law. The Series B convertible preferred stock is convertible, in whole or in part, into that number of shares of our common stock equal to the quotient of $1,000 per share divided by the conversion price. The "conversion price" was initially equal to $22.79 per share (or 125% of the closing price on the day the preferred stock was issued) and at no time can the Series B convertible preferred stock convert into shares of common stock at a discount to the closing price. The "closing price" equals $18.23 per share.

        The Series B convertible preferred stock is convertible at the option of the holder. Except with respect to an automatic conversion as described below, the conversion price shall initially be equal to 125% of the closing price (subject to adjustment) until the third anniversary of the original issue date of the Series B convertible preferred stock, which will be January 7, 2005. Upon the third anniversary of the original issue date, the conversion price shall be adjusted to be equal to either (i) the closing price, in the event that the average of the closing bid prices of our common stock as quoted on The Nasdaq National Market for the 20 trading days preceding the third anniversary of the original issuance (the "Future Price") is less than or equal to the closing price; (ii) the Future Price (as defined above) if the Future Price is greater than the closing price but less than 125% of the closing price; or (iii) 125% of the closing price if the Future Price is equal to or greater than 125% of the closing price. To the extent not previously converted, the Series B convertible preferred stock will automatically convert into shares of our common stock, based on the then effective conversion price, upon the earliest of (i) the fourth anniversary of the original issue date; (ii) immediately prior to an "asset transfer" or "acquisition" (as defined in the certificate of designation); or (iii) with the consent of the holders of a majority of the then outstanding Series B convertible preferred stock immediately prior to our liquidation, dissolution or winding up. In the event of an automatic conversion pursuant to an asset transfer, acquisition or liquidation, dissolution or winding up, the adjustment mechanism described above will be applied as if the common stock issuable upon conversion of the Series B convertible preferred were outstanding on the record date for that event.

        In the event of our liquidation, dissolution or winding down, either voluntary or involuntary, following the payment of any distributions due the holders of any class of capital stock or series of preferred stock that ranks senior to the Series B convertible preferred stock, the holders of the Series B convertible preferred stock shall be entitled to receive, prior and in preference to any distribution of any of our assets or surplus funds to the holders of our common stock or any class of capital stock or series of preferred stock that does not rank senior to or on parity with the Series B convertible preferred stock, an amount per share (as adjusted for any combinations, consolidations, stock distributions or stock dividends with respect to the Series B convertible preferred stock) equal to $1,000.

Additional Preferred Stock

        We will fix the rights, preferences, privileges and restrictions of the preferred stock of each series in the certificate of designation relating to that series. We will incorporate by reference as an exhibit to

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the registration statement that includes this prospectus or as an exhibit to a current report on Form 8-K, the form of any certificate of designation that describes the terms of the series of preferred stock we are offering before the issuance of the related series of preferred stock. This description will include:

        If we issue shares of preferred stock under this prospectus, the shares will be fully paid and nonassessable and will not have, or be subject to, any preemptive or similar rights.

        The Delaware General Corporation Law provides that the holders of preferred stock will have the right to vote separately as a class on a proposed amendment to our certificate of incorporation involving certain fundamental changes in the rights of holders of that preferred stock. This right is in addition to any voting rights that may be provided for in the applicable certificate of designation.

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        The issuance of preferred stock, whether pursuant to this offering or otherwise, could adversely affect the voting power, conversion or other rights of holders of common stock. Preferred stock could be issued quickly with terms calculated to delay or prevent a change in control of our company or make removal of management more difficult. Additionally, the issuance of preferred stock may have the effect of decreasing the market price of common stock.

Registration Rights

        As of the date hereof, certain purchasers of our Convertible Subordinated Notes due June 30, 2010 have included shares of our common stock for registration in a shelf registration statement filed with the SEC on September 17, 2003, as subsequently amended. We are required to pay all expenses in connection with such registration. The Company has also registered shares of common stock in separate, currently effective registration statements, pursuant to the Company's prior registration obligations.

Anti-Takeover Effects of Provisions of Delaware Law and Our Charter Documents.

Rights Plan

        We are subject to certain anti-takeover provisions under our share purchase rights plan. The rights issued and issuable pursuant to our share purchase rights plan trade with our common stock and are not currently exercisable. Under certain circumstances, the rights initially become exercisable for 1/100 share of our Series A junior participating preferred stock. The plan also provides that:

        The provisions described above may discourage, delay or prevent a third party from acquiring us. These provisions may also discourage, delay or prevent a third party from acquiring a large portion of our securities, or initiating a tender offer or proxy contest, even if our stockholders might receive a premium for their shares in the acquisition over then current market prices.

Certificate of Incorporation

        Our certificate of incorporation provides for our board of directors to be divided into three classes, with staggered three-year terms. As a result, only one class of directors will be elected at each annual meeting of stockholders, with the other classes continuing for the remainder of their respective three-year terms. Stockholders have no cumulative voting rights, and the stockholders representing a majority of the shares of common stock outstanding are able to elect all of the directors.

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        Our certificate of incorporation also requires that any action required or permitted to be taken by our stockholders must be effected at a duly called annual or special meeting of the stockholders and may not be effected by a consent in writing and that the stockholders may amend our bylaws or adopt new bylaws only by the affirmative vote of 662/3% of the outstanding voting securities. A special meeting of the stockholders may be called by our Chairman, our Chief Executive Officer, a resolution adopted by a majority of the total number of authorized directors or by stockholders owning 10% or more of the outstanding voting capital stock. These provisions may have the effect of delaying, deferring or preventing a change in control.

        The classification of our board of directors and lack of cumulative voting will make it more difficult for our existing stockholders to replace our board of directors as well as for another party to obtain control of us by replacing our board of directors. Since our board of directors has the power to retain and discharge our officers, these provisions could also make it more difficult for existing stockholders or another party to effect a change in management. These and other provisions may have the effect of deterring hostile takeovers or delaying changes in control or management. These provisions are intended to enhance the likelihood of continued stability in the composition of our board of directors and in the policies of our board of directors and to discourage certain types of transactions that may involve an actual or threatened change in control. These provisions are designed to reduce our vulnerability to an unsolicited acquisition proposal. The provisions also are intended to discourage certain tactics that may be used in proxy fights. However, such provisions could have the effect of discouraging others from making tender offers for our shares and, as a consequence, such provisions also may inhibit increases in the market price of our shares that could result from actual or rumored takeover attempts. Such provisions also may have the effect of preventing changes in our management.

Section 203 of the Delaware General Corporation Law

        We are subject to Section 203 of the Delaware General Corporation Law, which, subject to certain exceptions, prohibits a Delaware corporation from engaging in any business combination with any interested stockholder for a period of three years following the time that such stockholder became an interested stockholder, unless:

In general, Section 203 defines "business combination" to include the following:

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In general, Section 203 defines "interested stockholder" as an entity or person beneficially owning 15% or more of the outstanding voting stock of the corporation and any entity or person affiliated with or controlling or controlled by such entity or person or any affiliate or associate of the Corporation that was the owner of 15% or more of the outstanding voting stock of the corporation during the preceding three year period.

Certain Transactions

        Our bylaws provide that we will indemnify our directors and executive officers to the fullest extent permitted by Delaware law. Our bylaws also provide that we may indemnify our other officers, employees and other agents. We are also empowered under our bylaws to enter into indemnification contracts with our directors and officers and to purchase insurance on behalf of any person whom we are required or permitted to indemnify.

        In addition, our certificate of incorporation provides that the liability of our directors for monetary damages shall be eliminated, except for (i) breach of the directors duty of loyalty to us or our stockholders, (ii) acts or omissions not in good faith or which involve intentional misconduct or a knowing violation of law, (iii) violating Section 174 of the Delaware General Corporation Law, or (iv) any transaction from which the director derived an improper personal benefit. Pursuant to Delaware law and subject to the foregoing exceptions, our directors shall not be liable for monetary damages for breach of the directors' fiduciary duty of care to us and our stockholders. However, this provision does not eliminate the duty of care, and in appropriate circumstances, equitable remedies such as injunctive or other forms of nonmonetary relief remain available under Delaware law. The provision also does not affect a director's responsibilities under any other law, such as the federal securities laws or state or federal environmental laws.

Transfer Agent and Registrar

        Mellon Investor Services LLC is the transfer agent and registrar for our common stock. Mellon Investor Services' address is 235 Montgomery Street, 23rd Floor, San Francisco, CA 94104 and telephone number is (415) 743-1422.


DESCRIPTION OF DEBT SECURITIES

        The following description, together with the additional information we include in any applicable prospectus supplements, summarizes the material terms and provisions of the debt securities that we may offer under this prospectus. While the terms we have summarized below will apply generally to any future debt securities we may offer, we will describe the particular terms of any debt securities that we may offer in more detail in the applicable prospectus supplement. The terms of any debt securities we offer under a prospectus supplement may differ from the terms we describe below but shall not establish terms that contradict those contained in this prospectus.

        As of the date of filing of this prospectus, we have $209.7 million in outstanding debt which includes approximately $28,000 in outstanding debt held by Nektar Therapeutics UK, Ltd. We currently have $35.8 million of senior debt which is senior to our outstanding convertible subordinated notes. We

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may offer debt securities from time to time, in one or more series, as either senior or subordinated debt. Any subordinated debt securities that we issue pursuant to this prospectus or a prospectus supplement will be subordinate and junior in right of payment to all of our senior debt. We may issue debt securities which will be senior to our outstanding convertible subordinated notes, but subordinate to our senior debt. We may also issue debt securities which rank equally with or senior to our senior debt.

        We will issue the senior notes under the senior indenture which we will enter into with the trustee named in the senior indenture. We will issue the subordinated notes under the subordinated indenture which we will enter into with the trustee named in the subordinated indenture. We have filed forms of these documents as exhibits to the registration statement which includes this prospectus. We use the term "indentures" to refer to both the senior indenture and the subordinated indenture.

        The indentures will be qualified under the Trust Indenture Act of 1939. We use the term "debenture trustee" to refer to either the senior trustee or the subordinated trustee, as applicable.

        The following summaries of material provisions of the senior notes, the subordinated notes and the indentures are subject to, and qualified in their entirety by reference to, all the provisions of the indenture applicable to a particular series of debt securities. Except as we may otherwise indicate, the terms of the senior indenture and the subordinated indenture are identical.

General

        We will describe in each prospectus supplement the following terms relating to a series of debt securities:

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Conversion or Exchange Rights

        We will set forth in the prospectus supplement the terms on which a series of debt securities may be convertible into or exchangeable for our common stock, any other of our securities or securities of a third party. We will include provisions as to whether conversion or exchange is mandatory, at the option of the holder or at our option. We may include provisions pursuant to which the number of shares of our common stock, any other of our securities or securities of a third party that the holders of the series of debt securities receive would be subject to adjustment.

Consolidation, Merger or Sale

        The indentures in the forms initially filed as exhibits to the registration statement of which this prospectus is a part do not contain any covenant which restricts our ability to merge or consolidate, or sell, convey, transfer or otherwise dispose of all or substantially all of our assets. However, any successor of ours to, or acquirer of, such assets must assume all of our obligations under the indentures and the debt securities.

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        If the debt securities are convertible for our other securities or securities of other entities, the person with whom we consolidate or merge, or to whom we sell all of our property, must make provisions for the conversion of the debt securities into securities which the holders of the debt securities would have received if they had converted the debt securities before the consolidation, merger or sale.

Events of Default Under the Indenture

        The following are events of default under the indentures with respect to any series of debt securities that we may issue:

        If an event of default with respect to debt securities of any series occurs and is continuing, other than an event of default specified in the last bullet point above, the debenture trustee or the holders of at least 25% in aggregate principal amount of the outstanding debt securities of that series, by notice to us in writing, and to the debenture trustee if notice is given by such holders, may declare the unpaid principal of, premium, if any, and accrued interest, if any, due and payable immediately. If an event of default specified in the last bullet point above occurs with respect to us, the principal amount of and accrued interest, if any, of each issue of debt securities then outstanding shall be due and payable without any notice or other action on the part of the debenture trustee or any holder.

        The holders of a majority in principal amount of the outstanding debt securities of an affected series may waive any default or event of default with respect to the series and its consequences, except defaults or events of default regarding payment of principal, premium, if any, or interest, unless we have cured the default or event of default in accordance with the indenture.

        Subject to the terms of the indentures, if an event of default under an indenture shall occur and be continuing, the debenture trustee will be under no obligation to exercise any of its rights or powers under such indenture at the request or direction of any of the holders of the applicable series of debt securities, unless such holders have offered the debenture trustee reasonable indemnity. The holders of a majority in principal amount of the outstanding debt securities of any series will have the right to direct the time, method and place of conducting any proceeding for any remedy available to the debenture trustee, or exercising any trust or power conferred on the debenture trustee, with respect to the debt securities of that series, provided that:

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        A holder of the debt securities of any series will only have the right to institute a proceeding under the indentures or to appoint a receiver or trustee, or to seek other remedies if:

        These limitations do not apply to a suit instituted by a holder of debt securities if we default in the payment of the principal, premium, if any, or interest on, the debt securities.

        We will periodically file statements with the debenture trustee regarding our compliance with specified covenants in the indentures.

Modification of Indenture; Waiver

        We and the debenture trustee may change an indenture without the consent of any holders with respect to specific matters, including:

        In addition, under the indentures, the rights of holders of a series of debt securities may be changed by us and the debenture trustee with the written consent of the holders of at least a majority in aggregate principal amount of the outstanding debt securities of each series that is affected. However, we and the debenture trustee may only make the following changes with the consent of each holder of any outstanding debt securities affected:

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Discharge

        Each indenture provides that we can elect to be discharged from our obligations with respect to one or more series of debt securities, except for obligations to:

        In order to exercise our rights to be discharged, we must deposit with the debenture trustee money or government obligations sufficient to pay all the principal of, any premium, if any, and interest on, the debt securities of the series on the dates payments are due.

Form, Exchange and Transfer

        We will issue the debt securities of each series only in fully registered form without coupons and, unless we otherwise specify in the applicable prospectus supplement, in denominations of $1,000 and any integral multiple thereof. The indentures provide that we may issue debt securities of a series in temporary or permanent global form and as book-entry securities that will be deposited with, or on behalf of, The Depository Trust Company or another depository named by us and identified in a prospectus supplement with respect to that series. See "Legal Ownership of Securities" for a further description of the terms relating to any book-entry securities.

        At the option of the holder, subject to the terms of the indentures and the limitations applicable to global securities described in the applicable prospectus supplement, the holder of the debt securities of any series can exchange the debt securities for other debt securities of the same series, in any authorized denomination and of like tenor and aggregate principal amount.

        Subject to the terms of the indentures and the limitations applicable to global securities set forth in the applicable prospectus supplement, holders of the debt securities may present the debt securities for exchange or for registration of transfer, duly endorsed or with the form of transfer endorsed thereon duly executed if so required by us or the security registrar, at the office of the security registrar or at the office of any transfer agent designated by us for this purpose. Unless otherwise provided in the debt securities that the holder presents for transfer or exchange, we will make no service charge for any registration of transfer or exchange, but we may require payment of any taxes or other governmental charges.

        We will name in the applicable prospectus supplement the security registrar, and any transfer agent in addition to the security registrar, that we initially designate for any debt securities. We may at any time designate additional transfer agents or rescind the designation of any transfer agent or approve a change in the office through which any transfer agent acts, except that we will be required to maintain a transfer agent in each place of payment for the debt securities of each series.

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        If we elect to redeem the debt securities of any series, we will not be required to:

Information Concerning the Debenture Trustee

        The debenture trustee, other than during the occurrence and continuance of an event of default under an indenture, undertakes to perform only those duties as are specifically set forth in the applicable indenture. Upon an event of default under an indenture, the debenture trustee must use the same degree of care as a prudent person would exercise or use in the conduct of his or her own affairs. Subject to this provision, the debenture trustee is under no obligation to exercise any of the powers given it by the indentures at the request of any holder of debt securities unless it is offered reasonable security and indemnity against the costs, expenses and liabilities that it might incur.

Payment and Paying Agents

        Unless we otherwise indicate in the applicable prospectus supplement, we will make payment of the interest on any debt securities on any interest payment date to the person in whose name the debt securities, or one or more predecessor securities, are registered at the close of business on the regular record date for the interest.

        We will pay principal of and any premium and interest on the debt securities of a particular series at the office of the paying agents designated by us, except that unless we otherwise indicate in the applicable prospectus supplement, we will make interest payments by check which we will mail to the holder or by wire transfer to certain holders. Unless we otherwise indicate in a prospectus supplement, we will designate the corporate trust office of the debenture trustee in the City of New York as our sole paying agent for payments with respect to debt securities of each series. We will name in the applicable prospectus supplement any other paying agents that we initially designate for the debt securities of a particular series. We will maintain a paying agent in each place of payment for the debt securities of a particular series.

        All money we pay to a paying agent or the debenture trustee for the payment of the principal of or any premium or interest on any debt securities which remains unclaimed at the end of two years after such principal, premium or interest has become due and payable will be repaid to us, and the holder of the security thereafter may look only to us for payment thereof.

Governing Law

        The indentures and the debt securities will be governed by and construed in accordance with the laws of the State of New York.

Subordination of Subordinated Debt Securities

        The subordinated debt securities will be unsecured and will be subordinate and junior in priority of payment to certain of our other indebtedness to the extent described in a prospectus supplement. The indentures in the forms initially filed as exhibits to the registration statement of which this prospectus is a part do not limit the amount of indebtedness which we may incur and do not limit us from issuing any other secured or unsecured debt.

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DESCRIPTION OF WARRANTS

        The following description, together with the additional information we may include in any applicable prospectus supplements, summarizes the material terms and provisions of the warrants that we may offer under this prospectus and the related warrant agreements and warrant certificates. While the terms summarized below will apply generally to any warrants that we may offer, we will describe the particular terms of any series of warrants in more detail in the applicable prospectus supplement. If we indicate in the prospectus supplement, the terms of any warrants offered under that prospectus supplement may differ from the terms described below but shall not establish terms that contradict those provided in this prospectus. Specific warrant agreements will contain additional important terms and provisions and will be incorporated by reference as an exhibit to the registration statement that includes this prospectus or as an exhibit to a current report on Form 8-K.

General

        We will describe in the applicable prospectus supplement the terms of the series of warrants, including:

        Before exercising their warrants, holders of warrants will not have any of the rights of holders of the securities purchasable upon such exercise, including:

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Exercise of Warrants

        Each warrant will entitle the holder to purchase the securities that we specify in the applicable prospectus supplement at the exercise price that we describe in the applicable prospectus supplement. Unless we otherwise specify in the applicable prospectus supplement, holders of the warrants may exercise the warrants at any time up to 5:00 P.M. New York time on the expiration date that we set forth in the applicable prospectus supplement. After the close of business on the expiration date, unexercised warrants will become void.

        Holders of the warrants may exercise the warrants by delivering the warrant certificate representing the warrants to be exercised together with specified information, and paying the required amount to the warrant agent in immediately available funds, as provided in the applicable prospectus supplement. We will set forth on the reverse side of the warrant certificate and in the applicable prospectus supplement the information that the holder of the warrant will be required to deliver to the warrant agent.

        Upon receipt of the required payment and the warrant certificate properly completed and duly executed at the corporate trust office of the warrant agent or any other office indicated in the applicable prospectus supplement, we will issue and deliver the securities purchasable upon such exercise. If fewer than all of the warrants represented by the warrant certificate are exercised, then we will issue a new warrant certificate for the remaining amount of warrants. If we so indicate in the applicable prospectus supplement, holders of the warrants may surrender securities as all or part of the exercise price for warrants.

Enforceability of Rights by Holders of Warrants

        Each warrant agent will act solely as our agent under the applicable warrant agreement and will not assume any obligation or relationship of agency or trust with any holder of any warrant. A single bank or trust company may act as warrant agent for more than one issue of warrants. A warrant agent will have no duty or responsibility in case of any default by us under the applicable warrant agreement or warrant, including any duty or responsibility to initiate any proceedings at law or otherwise, or to make any demand upon us. Any holder of a warrant may, without the consent of the related warrant agent or the holder of any other warrant, enforce by appropriate legal action its right to exercise, and receive the securities purchasable upon exercise of, its warrants.


LEGAL OWNERSHIP OF SECURITIES

        We can issue debt securities or warrants in registered form or in the form of one or more global securities. We describe global securities in greater detail below. We refer to those persons who have debt securities or warrants registered in their own names on the books that we or any applicable trustee maintain for this purpose as the "holders" of those securities. These persons are the legal holders of the securities. We refer to those persons who, indirectly through others, own beneficial interests in securities that are not registered in their own names, as "indirect holders" of those securities. As we discuss below, indirect holders are not legal holders, and investors in securities issued in book-entry form or in street name will be indirect holders.

Book-Entry Holders

        We may issue securities in book-entry form only, as we will specify in the applicable prospectus supplement. This means those securities may be represented by one or more global securities registered

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in the name of a financial institution that holds them as depositary on behalf of other financial institutions that participate in the depositary's book-entry system. These participating institutions, which are referred to as participants, in turn, hold beneficial interests in the securities on behalf of themselves or their customers.

        Only the person in whose name a security is registered is recognized as the holder of that security. Securities issued in global form will be registered in the name of the depositary or its participants. Consequently, for securities issued in global form, we will recognize only the depositary as the holder of the securities, and we will make all payments on the securities to the depositary. The depositary passes along the payments it receives to its participants, which in turn pass the payments along to their customers who are the beneficial owners. The depositary and its participants do so under agreements they have made with one another or with their customers or because they are legally required to do so. They are not obligated to do so under the terms of the securities.

        As a result, investors in a book-entry security will not own securities directly. Instead, they will own beneficial interests in a global security, through a bank, broker or other financial institution that participates in the depositary's book-entry system or holds an interest through a participant. As long as the securities are issued in global form, investors will be indirect holders, and not holders, of the securities.

Street Name Holders

        In certain circumstances, we may terminate a global security or issue securities in non-global form. In these cases, investors may choose to hold their securities in their own names or in "street name." Securities held by an investor in street name would be registered in the name of a bank, broker or other financial institution that the investor chooses, and the investor would hold only a beneficial interest in those securities through an account he or she maintains at that institution.

        For securities held in street name, we will recognize only the intermediary banks, brokers and other financial institutions in whose names the securities are registered as the holders of those securities, and we will make all payments on those securities to them. These institutions pass along the payments they receive to their customers who are the beneficial owners, but only because they agree to do so in their customer agreements or because they are legally required to do so. They are not obligated to do so under the terms of the securities. Investors who hold securities in street name will be indirect holders, not holders, of those securities.

Legal Holders

        Our obligations, as well as the obligations of any applicable trustee and of any third parties employed by us or a trustee, run only to the legal holders of the securities. We do not have obligations to investors who hold beneficial interests in global securities, in street name or by any other indirect means. This will be the case whether an investor chooses to be an indirect holder of a security or has no choice because we are issuing the securities only in global form.

        For example, once we make a payment or give a notice to the holder, we have no further responsibility for the payment or notice even if that holder is required, under agreements with depositary participants or customers or by law, to pass it along to the indirect holders but does not do so. Similarly, we may want to obtain the approval of the holders to amend an indenture or warrant agreement, to relieve us of the consequences of a default or of our obligation to comply with a particular provision of the indenture or for other purposes. In such an event, we would seek approval only from the holders, and not the indirect holders, of the securities. Whether and how the holders contact the indirect holders is up to the holders.

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Special Considerations For Indirect Holders

        If you hold securities through a bank, broker or other financial institution, either in book-entry form or in street name, you should check with your own institution to find out:

Global Securities

        A global security is a security which represents one or any other number of individual securities held by a depositary. Generally, all securities represented by the same global securities will have the same terms.

        Each security issued in book-entry form will be represented by a global security that we deposit with and register in the name of a financial institution or its nominee that we select. The financial institution that we select for this purpose is called the depositary. Unless we specify otherwise in the applicable prospectus supplement, the Depository Trust Company, New York, New York, known as DTC, will be the depositary for all securities issued in book-entry form.

        A global security may not be transferred to or registered in the name of anyone other than the depositary, its nominee or a successor depositary, unless special termination situations arise. We describe those situations below under "Special Situations When a Global Security Will Be Terminated." As a result of these arrangements, the depositary, or its nominee, will be the sole registered owner and holder of all securities represented by a global security, and investors will be permitted to own only beneficial interests in a global security. Beneficial interests must be held by means of an account with a broker, bank or other financial institution that in turn has an account with the depositary or with another institution that does. Thus, an investor whose security is represented by a global security will not be a holder of the security, but only an indirect holder of a beneficial interest in the global security.

        If the prospectus supplement for a particular security indicates that the security will be issued in global form only, then the security will be represented by a global security at all times unless and until the global security is terminated. If termination occurs, we may issue the securities through another book-entry clearing system or decide that the securities may no longer be held through any book-entry clearing system.

Special Considerations For Global Securities

        As an indirect holder, an investor's rights relating to a global security will be governed by the account rules of the investor's financial institution and of the depositary, as well as general laws relating to securities transfers. We do not recognize an indirect holder as a holder of securities and instead deal only with the depositary that holds the global security.

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        If securities are issued only in the form of a global security, an investor should be aware of the following:

        There may be more than one financial intermediary in the chain of ownership for an investor. We do not monitor and are not responsible for the actions of any of those intermediaries.

Special Situations When A Global Security Will Be Terminated

        In a few special situations described below, the global security will terminate and interests in it will be exchanged for physical certificates representing those interests. After that exchange, the choice of whether to hold securities directly or in street name will be up to the investor. Investors must consult their own banks or brokers to find out how to have their interests in securities transferred to their own name, so that they will be direct holders. We have described the rights of holders and street name investors above.

        The global security will terminate when the following special situations occur:

        The prospectus supplement may also list additional situations for terminating a global security that would apply only to the particular series of securities covered by the prospectus supplement. When a

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global security terminates, the depositary, and not we or any applicable trustee, is responsible for deciding the names of the institutions that will be the initial direct holders.


PLAN OF DISTRIBUTION

        We may sell the securities through underwriters or dealers, through agents, or directly to one or more purchasers. The prospectus supplement will describe the terms of the offering of the securities, including:

        Only underwriters named in the prospectus supplement are underwriters of the securities offered by the prospectus supplement.

        If underwriters are used in the sale, they will acquire the securities for their own account and may resell them from time to time in one or more transactions at a fixed public offering price or at varying prices determined at the time of sale. The obligations of the underwriters to purchase the securities will be subject to the conditions set forth in the applicable underwriting agreement. We may offer the securities to the public through underwriting syndicates represented by managing underwriters or by underwriters without a syndicate. Subject to certain conditions, the underwriters will be obligated to purchase all the securities of the series offered by the prospectus supplement. Any public offering price and any discounts or concessions allowed or reallowed or paid to dealers may change from time to time. We may use underwriters with whom we have a material relationship. We will describe in the prospectus supplement, naming the underwriter, the nature of any such relationship.

        We may sell securities directly or through agents we designate from time to time. We will name any agent involved in the offering and sale of securities and we will describe any commissions we will pay the agent in the prospectus supplement. Unless the prospectus supplement states otherwise, our agent will act on a best-efforts basis for the period of its appointment.

        We may authorize agents or underwriters to solicit offers by certain types of institutional investors to purchase securities from us at the public offering price set forth in the prospectus supplement pursuant to delayed delivery contracts providing for payment and delivery on a specified date in the future. We will describe the conditions to these contracts and the commissions we must pay for solicitation of these contracts in the prospectus supplement.

        We may provide agents and underwriters with indemnification against certain civil liabilities, including liabilities under the Securities Act, or contribution with respect to payments that the agents or underwriters may make with respect to such liabilities. Agents and underwriters may engage in transactions with, or perform services for, us in the ordinary course of business.

        All securities we offer, other than common stock, will be new issues of securities with no established trading market. Any underwriters may make a market in these securities, but will not be obligated to do so and may discontinue any market making at any time without notice. We cannot guarantee the liquidity of the trading markets for any securities.

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        Any underwriter may engage in overallotment, stabilizing transactions, short covering transactions and penalty bids in accordance with Regulation M under the Exchange Act. Overallotment involves sales in excess of the offering size, which create a short position. Stabilizing transactions permit bids to purchase the underlying security so long as the stabilizing bids do not exceed a specified maximum. Short covering transactions involve purchases of the securities in the open market after the distribution is completed to cover short positions. Penalty bids permit the underwriters to reclaim a selling concession from a dealer when the securities originally sold by the dealer are purchased in a covering transaction to cover short positions. Those activities may cause the price of the securities to be higher than it would otherwise be. If commenced, the underwriters may discontinue any of the activities at any time.

        Any underwriters who are qualified market makers on The Nasdaq National Market may engage in passive market making transactions in the securities on The Nasdaq National Market in accordance with Rule 103 of Regulation M, during the business day prior to the pricing of the offering, before the commencement of offers or sales of the securities. Passive market makers must comply with applicable volume and price limitations and must be identified as passive market makers. In general, a passive market maker must display its bid at a price not in excess of the highest independent bid for such security; if all independent bids are lowered below the passive market maker's bid, however, the passive market maker's bid must then be lowered when certain purchase limits are exceeded.


LEGAL MATTERS

        The validity of the securities offered hereby will be passed upon for us by Cooley Godward LLP, Palo Alto, California.


EXPERTS

        Ernst & Young LLP, independent auditors, have audited our consolidated financial statements included in our Annual Report, as amended on Form 10-K/A, for the year ended December 31, 2003, as set forth in their report, which is incorporated by reference in this prospectus and elsewhere in the registration statement. Our financial statements are incorporated by reference in reliance on Ernst & Young LLP's report, given on their authority as experts in accounting and auditing.


WHERE YOU CAN FIND MORE INFORMATION

        We have filed with the SEC a registration statement on Form S-3 under the Securities Act with respect to the shares of common stock, preferred stock, debt securities and/or warrants that we are offering under this prospectus. This prospectus does not contain all of the information set forth in the registration statement and the exhibits to the registration statement. For further information with respect to us and the securities that we are offering under this prospectus, we refer you to the registration statement and the exhibits and schedules filed as a part of the registration statement.

        We are subject to the information and reporting requirements of the Exchange Act of 1934, under which we file periodic reports, proxy statements and other information with the SEC. Copies of the reports, proxy statements and other information may be examined without charge at the Public Reference Section of the SEC, 450 Fifth Street, N.W., Washington, D.C. 20549, and the SEC's Regional offices located at 5670 Wilshire Boulevard, Los Angeles, California 90036 or on the Internet at www.sec.gov. Copies of all or a portion of such materials can be obtained from the Public Reference Section of the SEC upon payment of prescribed fees. Please call the SEC at 800-SEC-0330 for further information about the Public Reference Room. These reports, proxy and information statements and other information may also be inspected at the offices of Nasdaq Operations, 1735 K Street, N.W., Washington, D.C. 20006.

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        We are "incorporating by reference" specified documents that we file with the SEC, which means:

        We incorporate by reference the documents listed below and any documents that we file in the future with the SEC under Section 13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of this prospectus and before the completion of the offering of the securities (other than current reports or portions thereof furnished under Item 2.02 or Item 7.01 of Form 8-K):

        You may request a copy of these filings, at no cost, by writing or telephoning us at the following address:

Nektar Therapeutics
150 Industrial Road
San Carlos, California 94070
(650) 631-3100
Attention: Secretary

Exhibits to the filings will not be sent, however, unless those exhibits have specifically been incorporated by reference in this document.

29


PART II

INFORMATION NOT REQUIRED IN THE PROSPECTUS

Item 14.    Other Expenses of Issuance and Distribution

        The following table sets forth the estimated costs and expenses, other than underwriting discounts and commissions, payable by the registrant in connection with the offering of the securities being registered. All amounts are estimated, except the SEC Registration Fee:

SEC Registration Fee   $ 31,675 (1)
Accounting Fees and Expenses   $ 50,000  
Legal Fees and Expenses   $ 40,000  
Printing and Miscellaneous expenses   $ 20,000  
Trustee's fees   $ 30,000  
  Total   $ 171,675  
(1)
Previously paid


Item 15.    Indemnification of Officers and Directors

        Under Section 145 of the Delaware General Corporation Law, we have broad powers to indemnify our directors and officers against liabilities they may incur in such capacities, including liabilities under the Securities Act of 1933, as amended (the "Securities Act").

        Our certificate of incorporation, as amended, provides for the elimination of liability for monetary damages for breach of our directors' fiduciary duty of care to us and our stockholders. These provisions do not eliminate our directors' duty of care and, in appropriate circumstances, equitable remedies such an injunctive or other forms of non-monetary relief will remain available under Delaware law. In addition, each director will continue to be subject to liability for breach of the director's duty of loyalty to us, for acts or omissions not in good faith or which involve intentional misconduct or a knowing violation of law, for any transaction from which the director derived an improper personal benefit and for violating Section 174 of the Delaware General Corporation Law. The provision does not affect a director's responsibilities under any other laws, such as the federal securities laws or state or federal environmental laws.

        We have entered into agreements with our directors and executive officers that require us to indemnify such persons against expenses, judgments, fines, settlements and other amounts actually and reasonably incurred (including expenses of a derivative action) in connection with any proceeding, whether actual or threatened, to which any such person may be made a party by reason of the fact that such person is or was a director or officer of us or any of our affiliated enterprises, provided such person acted in good faith and in a manner such person reasonably believed to be in or not opposed to the best interests of us and, with respect to any criminal proceeding, had no reasonable cause to believe his or her conduct was unlawful. The indemnification agreements also set forth certain procedures that will apply in the event of a claim for indemnification thereunder.

        The underwriting agreement (Exhibit 1.1) will provide for indemnification by any of our underwriters, our directors, our officers who sign the registration statement and our controlling persons for some liabilities, including liabilities arising under the Securities Act.

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Item 16.    Exhibits and Financial Statement Schedules


Exhibit
Number
    
   Description of Document
1.1   (11)   Form of underwriting agreement.
3.1   (1)   Certificate of Incorporation of Inhale Therapeutic Systems (Delaware), Inc.
3.2   (1)   Bylaws of Nektar Therapeutics.
3.3   (3)   Certificate of Amendment of the Amended Certificate of Incorporation of Nektar Therapeutics.
3.4   (6)   Certificate of Designation of Series A Junior Participating Preferred Stock of Nektar Therapeutics.
3.5   (7)   Certificate of Designation of Series B Convertible Preferred Stock of Nektar Therapeutics.
3.6   (8)   Certificate of Ownership and Merger of Nektar Therapeutics.
4.1       Reference is made to Exhibits 3.1, 3.2, 3.3, 3.4, 3.5 and 3.6.
4.2   (2)   Indenture, dated February 8, 2000, by and between Nektar Therapeutics, as Issuer, and Chase Manhattan Bank and Trust Company, National Association, as Trustee.
4.3   (8)   Specimen Common Stock certificate.
4.4   (4)   Specimen warrants to purchase shares of Common Stock.
4.5   (5)   Indenture, dated October 17, 2000, by and between Nektar Therapeutics, as Issuer, and Chase Manhattan Bank and Trust Company, National Association, as Trustee.
4.6   (6)   Rights Agreement, dated as of June 1, 2001, by and between Nektar Therapeutics and Mellon Investor Services LLC., as Rights Agent.
4.7   (6)   Form of Right Certificate.
4.8   (9)   Resale Registration Rights Agreement, dated June 30, 2003, by and among Nektar Therapeutics, Merrill Lynch, Pierce, Fenner & Smith Incorporated, Deutsche Bank Securities Inc., Lehman Brothers Inc., Friedman, Billings, Ramsey & Co., Inc. and SG Cowen Securities Corporation.
4.9   (10)   Specimen Preferred Stock Certificate and Form of Certificate of Designation of Preferred Stock.
4.10   (10)   Resale Registration Rights Agreement, dated October 9, 2003, by and among Nektar Therapeutics and J.P. Morgan Trust Company, National Association, as trustee.
4.11   (12)   Form of Senior Debt Indenture.
4.12   (12)   Form of Subordinated Debt Indenture.
4.13   (11)   Form of Senior Note.
4.14   (11)   Form of Subordinated Note.
4.15   (11)   Form of Warrant.
4.16   (11)   Form of Warrant Agreement.
5.1   (12)   Opinion of Cooley Godward LLP.
12.1   (13)   Statement RE: Ratio of Earnings to Fixed Charges.
23.1   (13)   Consent of Ernst & Young LLP, independent auditors.
23.2   (12)   Consent of Cooley Godward LLP (included in Exhibit 5.1).
24.1   (12)   Power of Attorney.
25.1   (12)   Statement of Eligibility of Trustee under the Senior Debt Indenture.
25.2   (12)   Statement of Eligibility of Trustee under the Subordinated Debt Indenture.
(1)
Incorporated by reference to the indicated exhibit in Nektar Therapeutics' Quarterly Report on Form 10-Q for the quarter ended June 30, 1998.

II-2

(2)
Incorporated by reference to the indicated exhibit in Nektar Therapeutics' Annual Report on Form 10-K for the year ended December 31, 1999.

(3)
Incorporated by reference to the indicated exhibit in Nektar Therapeutics' Quarterly Report on Form 10-Q for the quarter ended June 30, 2000.

(4)
Incorporated by reference to the indicated exhibit in Nektar Therapeutics' Quarterly Report on Form 10-Q for the quarter ended September 30, 2000.

(5)
Incorporated by reference to Nektar Therapeutics' Registration Statement on Form S-3 (No. 333-53678), filed on January 12, 2001.

(6)
Incorporated by reference to Nektar Therapeutics' Current Report on Form 8-K, filed on June 4, 2001.

(7)
Incorporated by reference to Nektar Therapeutics' Current Report on Form 8-K, filed on January 8, 2002.

(8)
Incorporated by reference to the indicated exhibit in Nektar Therapeutics' Current Report on Form 8-K, filed on January 23, 2003.

(9)
Incorporated by reference to Nektar Therapeutics' Current Report on Form 8-K, filed July 2, 2003.

(10)
Incorporated by reference to Nektar Therapeutics' Current Report on Form 8-K, filed November 3, 2003.

(11)
To be filed by amendment or as an exhibit to a current report of the registrant on Form 8-K and incorporated herein by reference.

(12)
Filed previously.

(13)
Filed herewith.


Item 17.    Undertakings

        The undersigned registrant hereby undertakes:

provided, however, that paragraphs (1)(i) and (1)(ii) do not apply if the registration statement is on Form S-3, Form S-8 or Form F-3, and the information required to be included in a post-effective

II-3

amendment by those paragraphs is contained in periodic reports filed with or furnished to the Commission by the registrant pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 that are incorporated by reference in the registration statement.

II-4


 SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, the registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-3 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the city of San Carlos, State of California, on December 6, 2004.

    NEKTAR THERAPEUTICS
(Registrant)

 
 
By:
 
/s/ AJAY BANSAL
Ajay Bansal
 Vice President, Finance and Administration and Chief Financial Officer (Principal Accounting and Financial Officer)

        Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed by the following persons in the capacities and on the dates indicated.

Signature
   Title
   Date

*
Ajit S. Gill
 
President, Chief Executive Officer and Director (Principal Executive Officer)
 
December 6, 2004

*
Robert B. Chess
 
Executive Chairman of the Board of Directors
 
December 6, 2004

/s/ AJAY BANSAL
Ajay Bansal
 
Vice President, Finance and Administration and Chief Financial Officer (Principal Accounting and Financial Officer)
 
December 6, 2004

*
John S. Patton, Ph.D.
 
Founder, Chief Scientific Officer and Director
 
December 6, 2004

*
Michael A. Brown
 
Director
 
December 6, 2004

*
Christopher A. Kuebler
 
Director
 
December 6, 2004

*
Irwin Lerner
 
Director
 
December 6, 2004

*
Melvin Perelman, Ph.D.
 
Director
 
December 6, 2004

*
Susan Wang
 
Director
 
December 6, 2004
             

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*
Roy A. Whitfield
 
Director
 
December 6, 2004

*By:
 
/s/ AJAY BANSAL
Ajay Bansal
 Attorney-in-fact
 
 
 
 

II-6


INDEX TO EXHIBITS

Exhibit
Number
    
   Description of Document
1.1   (11)   Form of underwriting agreement.
3.1   (1)   Certificate of Incorporation of Inhale Therapeutic Systems (Delaware), Inc.
3.2   (1)   Bylaws of Nektar Therapeutics.
3.3   (3)   Certificate of Amendment of the Amended Certificate of Incorporation of Nektar Therapeutics.
3.4   (6)   Certificate of Designation of Series A Junior Participating Preferred Stock of Nektar Therapeutics.
3.5   (7)   Certificate of Designation of Series B Convertible Preferred Stock of Nektar Therapeutics.
3.6   (8)   Certificate of Ownership and Merger of Nektar Therapeutics.
4.1       Reference is made to Exhibits 3.1, 3.2, 3.3, 3.4, 3.5 and 3.6.
4.2   (2)   Indenture, dated February 8, 2000, by and between Nektar Therapeutics, as Issuer, and Chase Manhattan Bank and Trust Company, National Association, as Trustee.
4.3   (8)   Specimen Common Stock certificate.
4.4   (4)   Specimen warrants to purchase shares of Common Stock.
4.5   (5)   Indenture, dated October 17, 2000, by and between Nektar Therapeutics, as Issuer, and Chase Manhattan Bank and Trust Company, National Association, as Trustee.
4.6   (6)   Rights Agreement, dated as of June 1, 2001, by and between Nektar Therapeutics and Mellon Investor Services LLC., as Rights Agent.
4.7   (6)   Form of Right Certificate.
4.8   (9)   Resale Registration Rights Agreement, dated June 30, 2003, by and among Nektar Therapeutics, Merrill Lynch, Pierce, Fenner & Smith Incorporated, Deutsche Bank Securities Inc., Lehman Brothers Inc., Friedman, Billings, Ramsey & Co., Inc. and SG Cowen Securities Corporation.
4.9   (10)   Specimen Preferred Stock Certificate and Form of Certificate of Designation of Preferred Stock.
4.10   (10)   Resale Registration Rights Agreement, dated October 9, 2003, by and among Nektar Therapeutics and J.P. Morgan Trust Company, National Association, as trustee.
4.11   (12)   Form of Senior Debt Indenture.
4.12   (12)   Form of Subordinated Debt Indenture.
4.13   (11)   Form of Senior Note.
4.14   (11)   Form of Subordinated Note.
4.15   (11)   Form of Warrant.
4.16   (11)   Form of Warrant Agreement.
5.1   (12)   Opinion of Cooley Godward LLP.
12.1   (13)   Statement RE: Ratio of Earnings to Fixed Charges.
23.1   (13)   Consent of Ernst & Young LLP, independent auditors.
23.2   (12)   Consent of Cooley Godward LLP (included in Exhibit 5.1).
24.1   (12)   Power of Attorney.
25.1   (12)   Statement of Eligibility of Trustee under the Senior Debt Indenture.
25.2   (12)   Statement of Eligibility of Trustee under the Subordinated Debt Indenture.
(1)
Incorporated by reference to the indicated exhibit in Nektar Therapeutics' Quarterly Report on Form 10-Q for the quarter ended June 30, 1998.

(2)
Incorporated by reference to the indicated exhibit in Nektar Therapeutics' Annual Report on Form 10-K for the year ended December 31, 1999.

(3)
Incorporated by reference to the indicated exhibit in Nektar Therapeutics' Quarterly Report on Form 10-Q for the quarter ended June 30, 2000.

(4)
Incorporated by reference to the indicated exhibit in Nektar Therapeutics' Quarterly Report on Form 10-Q for the quarter ended September 30, 2000.

(5)
Incorporated by reference to Nektar Therapeutics' Registration Statement on Form S-3 (No. 333-53678), filed on January 12, 2001.

(6)
Incorporated by reference to Nektar Therapeutics' Current Report on Form 8-K, filed on June 4, 2001.

(7)
Incorporated by reference to Nektar Therapeutics' Current Report on Form 8-K, filed on January 8, 2002.

(8)
Incorporated by reference to the indicated exhibit in Nektar Therapeutics' Current Report on Form 8-K, filed on January 23, 2003.

(9)
Incorporated by reference to Nektar Therapeutics' Current Report on Form 8-K, filed July 2, 2003.

(10)
Incorporated by reference to Nektar Therapeutics' Current Report on Form 8-K, filed November 3, 2003.

(11)
To be filed by amendment or as an exhibit to a current report of the registrant on Form 8-K and incorporated herein by reference.

(12)
Filed previously.

(13)
Filed herewith.



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TABLE OF CONTENTS
ABOUT THIS PROSPECTUS
NEKTAR THERAPEUTICS
RISK FACTORS
FORWARD-LOOKING STATEMENTS
THE SECURITIES WE MAY OFFER
RATIO OF EARNINGS TO FIXED CHARGES
USE OF PROCEEDS
DESCRIPTION OF CAPITAL STOCK
DESCRIPTION OF DEBT SECURITIES
DESCRIPTION OF WARRANTS
LEGAL OWNERSHIP OF SECURITIES
PLAN OF DISTRIBUTION
LEGAL MATTERS
EXPERTS
WHERE YOU CAN FIND MORE INFORMATION
PART II INFORMATION NOT REQUIRED IN THE PROSPECTUS
SIGNATURES
INDEX TO EXHIBITS

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Exhibit 12.1


Nektar Therapeutics
Statement RE: Ratio of Earnings to Fixed Charges
(in thousands, except for ratios)

 
   Year Ended December 31,
   Nine Months Ended September 30,
  
 
   2003
   2002
   2001
   2000
   1999
   2004
   2003
  
RATIO OF EARNINGS TO FIXED CHARGES                                            
Loss before income taxes and cumulative effect of accounting change   $ (65,721 ) $ (107,468 ) $ (250,008 ) $ (97,403 ) $ (38,448 ) $ (82,484 ) $ (50,194 )
Add: Fixed charges     19,670     18,293     16,297     13,726     2,470     22,847     14,762  
Less: Capitalized interest     —     —     (1,230 )   —     —     —     —  
   
 
 
 
 
 
 
 
Earnings   $ (46,051 ) $ (89,175 ) $ (234,941 ) $ (83,677 ) $ (35,978 ) $ (59,637 ) $ (35,432 )

Interest expense
 
$
17,897
 
$
16,613
 
$
13,431
 
$
12,138
 
$
2,075
 
$
21,864
 
$
13,083
 
Amortization of debt issuance costs     1,430     1,268     1,366     1,254     131     739     1,421  
Capitalized interest     —     —     1,230     —     —     —     —  
Estimated interest portion of rental expense     343     412     270     334     264     244     258  
   
 
 
 
 
 
 
 
Fixed charges   $ 19,670   $ 18,293   $ 16,297   $ 13,726   $ 2,470   $ 22,847   $ 14,762  
   
 
 
 
 
 
 
 
Excess (deficiency) of earnings available to cover fixed charges   $ (65,721 ) $ (107,468 ) $ (251,238 ) $ (97,403 ) $ (38,448 ) $ (82,484 ) $ (50,194 )
   
 
 
 
 
 
 
 
Preference dividends   $ —   $ —   $ —   $ —   $ —   $ —   $ —  
   
 
 
 
 
 
 
 
Ratio of Earnings to Fixed Charges     N/A     N/A     N/A     N/A     N/A     N/A     N/A  
Ratio of Fixed Charges and Preference Dividends to Earnings     N/A     N/A     N/A     N/A     N/A     N/A     N/A  



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Exhibit 23.1


CONSENT OF ERNST & YOUNG LLP, INDEPENDENT AUDITORS

We consent to the reference to our firm under the caption "Experts" in the Registration Statement (Form S-3 No. 333-120009) and related Prospectus of Nektar Therapeutics for the registration of $250,000,000 of common stock, preferred stock, debt securities and warrants, and to the incorporation by reference therein of our report dated February 19, 2004, except for Note 1, as to which the date is April 13, 2004, with respect to the consolidated financial statements of Nektar Therapeutics (formerly Inhale Therapeutic Systems, Inc.) included in its Annual Report (Form 10-K/A) for the year ended December 31, 2003, filed with the Securities and Exchange Commission.

/s/ ERNST & YOUNG LLP

Palo Alto, California
December 2, 2004



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CONSENT OF ERNST & YOUNG LLP, INDEPENDENT AUDITORS