UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 13G UNDER THE SECURITIES EXCHANGE ACT OF 1934 (AMENDMENT NO. 3)* Nektar Therapeutics -------------------------------------------------------------------------------- (Name of Issuer) Common Stock -------------------------------------------------------------------------------- (Title of Class of Securities) 640268-10-8 -------------------------------------------------------- (CUSIP Number) April 30, 2004 -------------------------------------------------------------------------------- (Date of Event Which Requires Filing of this Statement) Check the appropriate box to designate the rule pursuant to which this Schedule is filed: / / Rule 13d-1(b) /X/ Rule 13d-1(c) / / Rule 13d-1(d) *The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page. The information required in the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes). Page 1 of 6 Pages SCHEDULE 13G CUSIP NO. 457191-10-4 Page 2 of 6 Pages ------------------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Citigroup Inc. ------------------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS) (a) / / (b) / / ------------------------------------------------------------------------------- (3) SEC USE ONLY ------------------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION Delaware ------------------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER 0 SHARES ---------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 1,811,577* ** OWNED BY ---------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER 0 REPORTING ---------------------------------------------------- PERSON (8) SHARED DISPOSITIVE POWER 1,811,577* ** WITH: ------------------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,811,577* ** ------------------------------------------------------------------------------- (10) CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS) / / ------------------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 2.2%* ** ------------------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) HC ------------------------------------------------------------------------------- * Assumes conversion/exercise of certain securities held. ** Includes shares held by other reporting person. Item 1(a). Name of Issuer: Nektar Therapeutics Item 1(b). Address of Issuer's Principal Executive Offices: 150 Industrial Road San Carlos, California 94070 Item 2(a). Name of Person Filing: Citigroup Inc. ("Citigroup") Item 2(b). Address or Principal Office or, if none, Residence: The address of the principal office of Citigroup is: 399 Park Avenue New York, NY 10043 Item 2(c). Citizenship or Place of Organization: Citigroup is a Delaware corporation. Item 2(d). Title of Class of Securities: Common Stock Item 2(e). Cusip Number: 640268-10-8 Page 3 of 6 Pages Item 3. If this Statement is Filed Pursuant to Sections 240.13d-1(b) or 240.13d-2(b) or (c), Check Whether the Person Filing is a(n): (a) [ ] Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o); (b) [ ] Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c); (c) [ ] Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c); (d) [ ] Investment company registered under Section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8); (e) [ ] Investment adviser in accordance with Section 240.13d-1(b)(1)(ii)(E); (f) [ ] Employee benefit plan or endowment fund in accordance with Section 240.13d-1(b)(1)(ii)(F); (g) [ ] Parent holding company or control person in accordance with Section 240.13d-1(b)(1)(ii)(G); (h) [ ] Savings association as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813); (i) [ ] Church plan that is excluded from the definition of an investment company under Section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3) (j) [ ] Group, in accordance with Section 240.13d-1(b)(1)(ii)(J). Item 4. Ownership. (as of April 30, 2004) (a) Amount beneficially owned: See item 9 of cover page (b) Percent of Class: See item 11 of cover page (c) Number of shares as to which the person has: (i) sole power to vote or to direct the vote: (ii) shared power to vote or to direct the vote: (iii) sole power to dispose or to direct the disposition of: (iv) shared power to dispose or to direct the disposition of: See Items 5-8 of cover page Page 4 of 6 Pages Item 5. Ownership of Five Percent or Less of a Class. If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following [X]. Item 6. Ownership of More Than Five Percent on Behalf of Another Person. Not Applicable. Item 7. Identification of the Subsidiary which Acquired the Security being Reported on by the Parent Holding Company. See Exhibit 1 for the identity of the subsidiaries which directly beneficially own the securities reported herein. Item 8. Identification and Classification of Members of the Group. Not Applicable. Item 9. Notice of Dissolution of Group. Not Applicable. Page 5 of 6 Pages Item 10. Certification. By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect. SIGNATURE. After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct. Dated: May 10, 2004 CITIGROUP INC. By: /s/ Serena D. Moe -------------------------------------- Name: Serena D. Moe Title: Assistant Secretary Page 6 of 6 Pages EXHIBIT INDEX TO SCHEDULE 13G ----------------------------- EXHIBIT 1 --------- Identification of the Subsidiaries which acquired the securities being reported by the Parent Holding Company(s).