Filed Pursuant to Rule 424(b)(3)
                                                      Registration No. 333-46930

                           PROSPECTUS ADDENDUM
                           (TO PROSPECTUS SUPPLEMENT DATED NOVEMBER 21, 2002
                           AND PROSPECTUS DATED FEBRUARY 27, 2003)

          PRINCIPAL PROTECTED NOTES

        UBS AG $14,500,000 NOTES LINKED TO THE S&P 500(R) INDEX DUE DECEMBER 7,
        2007

        The initial offering of these securities took place in November
        2002. When we initially offered these securities, we prepared a
        prospectus supplement dated November 21, 2002. We delivered this
        prospectus supplement attached to a "base" prospectus dated May
        17, 2001.

        We have now prepared a new "base" prospectus, dated February 27,
        2003. This new base prospectus replaces the original base
        prospectus dated May 17, 2001. However, since the terms of the
        securities have remained the same, we are continuing to use the
        original prospectus supplement.

        As a result, you should read the attached prospectus supplement,
        which gives the specific terms of your securities, together with
        the attached new base prospectus dated February 27, 2003. When
        you read these documents, please note that:

             - Any references in the prospectus supplement to the
               original base prospectus dated May 17, 2001 should be read
               to refer instead to the attached new base prospectus dated
               February 27, 2003.

             - Any references to the section "Description of Notes We May
               Offer" in the original base prospectus now refer instead
               to the section "Description of Debt Securities We May
               Offer" in the new base prospectus.

             - Any references to the section "Description of Notes We May
               Offer--Legal Ownership of Notes" in the original base
               prospectus now refer instead to the section "Legal
               Ownership and Book-Entry Issuance" in the new base
               prospectus.

        In addition, please disregard the table of contents for the
        original base prospectus dated May 17, 2001 that is provided on
        the back cover of the attached prospectus supplement. A table of
        contents for the new base prospectus is provided on page 2 of the
        new base prospectus.

        UBS AG, UBS Warburg LLC and UBS PaineWebber Inc. and other
        affiliates of UBS AG may use this prospectus addendum, together
        with the attached prospectus supplement and new base prospectus,
        in connection with offers and sales of the securities in
        market-making transactions. Please see "Supplemental Plan of
        Distribution" in the attached prospectus supplement and "Plan of
        Distribution" in the attached base prospectus.

        UBS WARBURG            UBS PAINEWEBBER INC.
        Prospectus Addendum dated February 27, 2003
                                                                     UBS LOGO