EXHIBIT 10.24

*    Represents confidential information for which Ariba, Inc. is seeking
     confidential treatment with the Securities and Exchange Commission.

                               AMENDMENT NO. 1 TO
                            STOCK PURCHASE AGREEMENT

     THIS AMENDMENT NO. 1 TO STOCK PURCHASE AGREEMENT ("Amendment") is made as
of December 10, 2001, by and among Nihon Ariba K.K., a Japanese corporation (the
"Company"), SOFTBANK Corp., a Japanese corporation ("SOFTBANK Parent") and
SOFTBANK EC Holdings Corp., a Japanese corporation previously known as SOFTBANK
E-Commerce Corp. and a direct wholly owned subsidiary of SOFTBANK Parent
("SOFTBANK" and together with SOFTBANK Parent, the "Investors").

                                 R E C I T A L S
                                 ---------------

     WHEREAS, the Company and the Investors entered into that certain Stock
Purchase Agreement, dated as of October 19, 2000 (the "Stock Purchase
Agreement"); and

     WHEREAS, concurrently herewith, the Investors and certain other parties are
amending and/or entering into other agreements relating to the business and
affairs of the Company, and the parties hereto now wish to amend the Stock
Purchase Agreement as set forth in this Amendment.

     NOW, THEREFORE, in consideration of the promises and conditions contained
herein, the parties hereby agree to amend the Stock Purchase Agreement as
follows:

     1. Sections 7.1 and 7.2 of the Stock Purchase Agreement be, and they hereby
are, deleted in their entirety.

     2. Section 8.2 of the Stock Purchase Agreement be, and it hereby is,
amended and restated in its entirety to read in full as follows:

          "8.2 Termination. This Agreement may be terminated as follows:

               (a)  Upon the parties' mutual written agreement.

               (b)  If any of the Company, Ariba or either Investor fails to
                    perform, in any material respect, any of its material
                    obligations hereunder or under any of the other Transaction
                    Agreements, and if such default continues for a period of
                    thirty (30) days after the date the defaulting party first
                    receives written notice of such default from either Investor
                    (if Ariba or the Company is the defaulting party) or Ariba
                    or the Company (if either of the Investors is the defaulting
                    party), then either Investor (if Ariba or the Company is the
                    defaulting party) or the Company (if either of the Investors
                    is the defaulting party) shall have the right to terminate
                    this Agreement effective immediately upon written notice to
                    the defaulting party at any time after such thirty (30)-day
                    period.



               (c)  Notwithstanding the foregoing, the right of the Investors to
                    terminate this Agreement pursuant to Section 8.2(b), as a
                    result of a default of the Company, shall exist only if [*]
                    and only if [*] (as defined in the Shareholders Agreement)
                    is in effect.

               (d)  Any of the Company or the Investors shall have the right to
                    terminate this Agreement, effective immediately upon written
                    notice to the other party, in the event that the Company
                    (where an Investor is the party giving notice) or an
                    Investor (where the Company is the party giving notice) is
                    dissolved, liquidated or declared bankrupt or a filing for
                    voluntary or involuntary bankruptcy, civil rehabilitation or
                    for the application of other similar insolvency or
                    rehabilitation procedures is made by such party.

               (e)  Notwithstanding the foregoing, Section 7.3 and Article 9
                    (except for Section 9.6, which shall not survive
                    termination) shall survive a termination of the Agreement.
                    Termination of this Agreement for any reason shall not
                    release any party from any liability or obligation which has
                    already accrued as of the effective date of such
                    termination, and shall not constitute a waiver or release
                    of, or otherwise be deemed to prejudice or adversely affect,
                    any rights, remedies or claims, whether for damages or
                    otherwise, which a party may have hereunder, at law, equity
                    or otherwise or which may arise out of or in connection with
                    such termination.

               (f)  For purposes of this Section 8.2, the term "Transaction
                    Agreements" shall include this Agreement, the Shareholders
                    Agreement and the amended and restated letter agreement
                    dated December 10, 2001 between SOFTBANK Parent and Ariba."

     3. Section 9.1 of the Stock Purchase Agreement be, and it hereby is,
amended and restated in its entirety to read in full as follows:

          "9.1 Governing Law; Dispute Resolution. The validity, construction and
     enforceability of this Agreement and all related agreements, collectively
     or separately, shall be governed by and construed in accordance with the
     laws of the State of California. The parties shall attempt to resolve all
     disputes between the parties arising out of or relating to this Agreement
     amicably through good faith discussions upon the written request of any
     party. In the event that any such dispute cannot be resolved thereby within
     a period of sixty (60) days after such notice has been given (the last day
     of such sixty (60) day period being herein referred to as the "Arbitration
     Date"), such dispute shall be finally settled by arbitration in San
     Francisco, California, using the English language in accordance with the
     Arbitration Rules and Procedures of JAMS then in effect, by one or more
     commercial arbitrator(s) with substantial experience in resolving complex
     commercial contract disputes, who may or may not be selected from the
     appropriate list of JAMS arbitrators. If the parties cannot agree upon the
     number and identity of the arbitrators within fifteen (15) days following
     the Arbitration Date, then a single arbitrator shall be selected on an
     expedited basis in accordance with the Arbitration Rules and Procedures of
     JAMS, provided that any arbitrator so selected shall have substantial
     experience in the software industry. The arbitrator(s) shall have the
     authority to grant specific performance and to allocate between the parties
     the costs of arbitration (including service fees, arbitrator fees and all
     other fees related to the arbitration) in such equitable manner as the
     arbitrator(s) may determine. The prevailing party in the arbitration shall
     be entitled to receive reimbursement of its reasonable


                                       2



     expenses (including reasonable attorneys' fees, expert witness fees and all
     other expenses) incurred in connection therewith. Judgment upon the award
     so rendered may be entered in a court having jurisdiction or application
     may be made to such court for judicial acceptance of any award and an order
     of enforcement, as the case may be. Notwithstanding the foregoing, each
     party shall have the right to institute an action in a court of proper
     jurisdiction for preliminary injunctive relief pending a final decision by
     the arbitrator(s), provided that a permanent injunction and damages shall
     only be awarded by the arbitrator(s). For all purposes of this Section 9.1,
     the parties consent to exclusive jurisdiction and venue in the United
     States federal Courts located in the Northern District of California. For
     the avoidance of doubt, the validity, construction, and enforceability of
     this Agreement and the resolution of disputes arising out of and relating
     to this Agreement and any related agreements (other than an action solely
     between Nihon Ariba K.K. and Softbank Commerce Corporation relating solely
     to the Amended Master Alliance Agreement), collectively or separately,
     shall be governed solely by this Section 9.1, notwithstanding that (i) the
     Amended Master Alliance Agreement is governed by Japanese law and uses a
     different dispute resolution procedure or (ii) disputes arising out of or
     relating to this Agreement are, or are asserted to, in any way relate to or
     be based on similar facts as disputes arising out of or relating to the
     Amended Master Alliance Agreement."

     4. Section 9.2(c) of the Stock Purchase Agreement be, and it hereby is,
amended and restated in its entirety to read in full as follows:

          " (b) If to SOFTBANK

                [*]

                with a copy to:

                [*]

            (c) If to the Company [*]

                with a copy to:

                [*]"


     5. Miscellaneous.

     5.1 Successors and Assigns. Except as otherwise provided herein, the terms
and conditions of this Amendment shall inure to the benefit of and be binding
upon the respective permitted successors and assigns of the parties.

     5.2 Counterparts. This Amendment 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.


                                       3



     5.3 Amendments and Waivers. Any term of this Amendment may be amended only
with the written consent of the parties. Except as explicitly stated in this
Amendment, all terms, conditions and provisions of the Stock Purchase Agreement
remain unchanged by this Amendment and shall continue in full force and effect.

(Signatures on following page.)



                                       4



     IN WITNESS WHEREOF, the parties have executed this Amendment as of the date
first above written.

                                       COMPANY:

                                       NIHON ARIBA K.K.

                                       By:   /s/ Kuniaki Watanabe
                                           -------------------------------------
                                       Title:   President and CEO
                                              ----------------------------------



                                       INVESTORS:

                                       SOFTBANK EC HOLDINGS CORP.

                                       By:  /s/ Ken Miyauchi
                                           -------------------------------------
                                       Title:  President and CEO
                                              ----------------------------------




                                       SOFTBANK CORP.

                                       By:   /s/ Masayoshi Son
                                           -------------------------------------
                                       Title:   President and CEO
                                              ----------------------------------



                      SIGNATURE PAGE TO AMENDMENT NO.1 TO
                            STOCK PURCHASE AGREEMENT