SCHEDULE 13G
CUSIP NO. 640268108                                         PAGE 10 OF 10 PAGES



                                                                       Exhibit I

                             JOINT FILING AGREEMENT

     This will confirm the agreement by and among the undersigned that the
Schedule 13G filed with the Securities and Exchange Commission on or about the
date hereof with respect to the beneficial ownership by the undersigned of the
Common Stock, $0.0001 par value, of Nektar Therapeutics, a Delaware corporation,
is being filed, and all amendments thereto will be filed, on behalf of each of
the persons and entities named below in accordance with Rule 13d-1(k) under the
Securities Exchange Act of 1934, as amended. This Agreement may be executed in
two or more counterparts, each of which shall be deemed an original, but all of
which together shall constitute one and the same instrument.

Dated as of February 3, 2004



                    ALEXANDRA GLOBAL MASTER FUND LTD.

                    By: ALEXANDRA INVESTMENT MANAGEMENT, LLC,
                        its Investment Advisor

                    By: /s/ Mikhail A. Filimonov
                        ----------------------------
                        Mikhail A. Filimonov
                        Title: Managing Member

                    ALEXANDRA INVESTMENT MANAGEMENT, LLC

                    By: /s/ Mikhail A. Filimonov
                        ----------------------------
                        Mikhail A. Filimonov
                        Title: Managing Member

                    /s/ Mikhail A. Filimonov
                    ----------------------------
                    Mikhail A. Filimonov

                    /s/ Dimitri Sogoloff
                    ----------------------------
                    Dimitri Sogoloff