UNITED STATES

                       SECURITIES AND EXCHANGE COMMISSION

                             WASHINGTON, D.C. 20549

                                  SCHEDULE 13G

                    Under the Securities Exchange Act of 1934

                                (Amendment No. )*

                              Nektar Therapeutics
                              -------------------
                                (Name of Issuer)

                                  Common Stock
                         ------------------------------
                         (Title of Class of Securities)

                                    457191104
                                 --------------
                                 (CUSIP Number)

                                December 31, 2002
             -------------------------------------------------------
             (Date of Event Which Requires Filing of this Statement)


             Check the appropriate box to designate the rule pursuant to which
this Schedule is filed:

                                [x] Rule 13d-1(b)

                                [ ] 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 9 pages






--------------------                                          -----------------
CUSIP No.  457191104                   13G                    Page 2 of 9 Pages
--------------------                                          -----------------
--------------------------------------------------------------------------------
  1     NAME OF REPORTING PERSON
        S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

            Liberty Wanger Asset Management, L.P.  36-3820584
--------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

            Not Applicable                                         (a) [  ]
                                                                   (b) [  ]
--------------------------------------------------------------------------------
  3     SEC USE ONLY
--------------------------------------------------------------------------------
  4     CITIZENSHIP OR PLACE OF ORGANIZATION

            Delaware
--------------------------------------------------------------------------------
     NUMBER OF          5    SOLE VOTING POWER

       SHARES                    None
                       ---------------------------------------------------------

    BENEFICIALLY        6    SHARED VOTING POWER

      OWNED BY                   3,748,000
                       ---------------------------------------------------------
        EACH            7    SOLE DISPOSITIVE POWER

     REPORTING                   None
                       ---------------------------------------------------------
    PERSON WITH         8    SHARED DISPOSITIVE POWER

                                 3,748,000
--------------------------------------------------------------------------------
  9     AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            3,748,000
--------------------------------------------------------------------------------
  10   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*

           Not Applicable                                                   [  ]
--------------------------------------------------------------------------------
  11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

           6.8%
--------------------------------------------------------------------------------
  12   TYPE OF REPORTING PERSON*

           IA
--------------------------------------------------------------------------------

                      *SEE INSTRUCTION BEFORE FILLING OUT!




--------------------                                          -----------------
CUSIP No.  457191104                   13G                    Page 3 of 9 Pages
--------------------                                          -----------------
--------------------------------------------------------------------------------
  1     NAME OF REPORTING PERSON
        S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

            WAM Acquisition GP. Inc.
--------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

            Not Applicable                                         (a) [  ]
                                                                   (b) [  ]
--------------------------------------------------------------------------------
  3     SEC USE ONLY
--------------------------------------------------------------------------------
  4     CITIZENSHIP OR PLACE OF ORGANIZATION

            Delaware
--------------------------------------------------------------------------------
     NUMBER OF          5    SOLE VOTING POWER

       SHARES                    None
                       ---------------------------------------------------------

    BENEFICIALLY        6    SHARED VOTING POWER

      OWNED BY                   3,748,000
                       ---------------------------------------------------------
        EACH            7    SOLE DISPOSITIVE POWER

     REPORTING                   None
                       ---------------------------------------------------------
    PERSON WITH         8    SHARED DISPOSITIVE POWER

                                 3,748,000
--------------------------------------------------------------------------------
  9     AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            3,748,000
--------------------------------------------------------------------------------
  10   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*

           Not Applicable                                                   [  ]
--------------------------------------------------------------------------------
  11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

           6.8%
--------------------------------------------------------------------------------
  12   TYPE OF REPORTING PERSON*

           CO
--------------------------------------------------------------------------------

                      *SEE INSTRUCTION BEFORE FILLING OUT!


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:

                         Liberty Wanger Asset Management, L.P. ("WAM")
                         WAM Acquisition GP, Inc., the general partner of WAM
                            ("WAM GP")


Item 2(b)       Address of Principal Business Office:

                         WAM and WAM GP are both located at:

                         227 West Monroe Street, Suite 3000
                         Chicago, Illinois  60606


Item 2(c)       Citizenship:

                        WAM is a Delaware limited partnership; and WAM GP is a
                        Delaware corporation.

Item 2(d)       Title of Class of Securities:

                        Common Stock

Item 2(e)       CUSIP Number:

                        457191104

Item 3          Type of Person:

                        (e)   WAM is an Investment Adviser registered under
                              section 203 of the Investment Advisers Act of
                              1940; WAM GP is the General Partner of the
                              Investment Adviser.

                               Page 4 of 9 pages




Item 4     Ownership (at December 31, 2002):

                        (a)   Amount owned "beneficially" within the meaning of
                              rule 13d-3:

                              3,748,000

                        (b)   Percent of class:

                              6.8% (based on 55,422,665 shares outstanding as of
                              October 31, 2002).

                        (c)   Number of shares as to which such person has:

                              (i)    sole power to vote or to direct
                                     the vote: none

                              (ii)   shared power to vote or to direct the vote:
                                      3,748,000

                              (iii)  sole power to dispose or to direct the
                                     disposition of: none

                              (iv)   shared power to dispose or to direct
                                     disposition of: 3,748,000

Item 5     Ownership of Five Percent or Less of a Class:

                        Not Applicable

Item 6     Ownership of More than Five Percent on Behalf of Another Person:

                        The shares reported herein have been acquired on behalf
                        of discretionary clients of WAM. Persons other than WAM
                        and WAM GP are entitled to receive all dividends from,
                        and proceeds from the sale of, those shares.

Item 7     Identification and Classification of the Subsidiary Which Acquired
           the Security Being Reported on by the Parent Holding Company:

                        Not Applicable

Item 8     Identification and Classification of Members of the Group:

                        Not Applicable

Item 9     Notice of Dissolution of Group:

                        Not Applicable

                               Page 5 of 9 pages






Item 10     Certification:

                        By signing below I certify that, to the best of my
            knowledge and belief, the securities referred to above were acquired
            and are held in the ordinary course of business and 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.

                               Page 6 of 9 pages



                                    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.

Date:  February 10, 2003


                           The undersigned corporation, on the date above
                           written, agrees and consents to the joint filing on
                           its behalf of this Schedule 13G in connection with
                           its beneficial ownership of the security reported
                           herein.

                               WAM Acquisition GP, Inc.
                                   for itself and as general partner of
                                   LIBERTY WANGER ASSET
                                   MANAGEMENT, L.P.



                               By:  /s/ Bruce H. Lauer
                                    ------------------------------------------
                                        Bruce H. Lauer
                                        Senior Vice President and Secretary

                               Page 7 of 9 pages



                                  Exhibit Index

Exhibit 1         Joint Filing Agreement dated as of February 10, 2003 by and
                  among Liberty Wanger Asset Management, L.P. and WAM
                  Acquisition GP, Inc.

                               Page 8 of 9 pages