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                                                                     EXHIBIT 4.1

                             SIEBEL SYSTEMS, INC.

                          Certificate of Designation

                        (Pursuant to Section 151 of the
                       Delaware General Corporation Law)

                           SERIES A1 PREFERRED STOCK

Siebel Systems, Inc., a corporation organized and existing under the General
Corporation Law of the State of Delaware (the "Company") hereby certifies that
the following resolutions were duly adopted by the Board of Directors of the
Company (the "Board") on November 2, 2000, as required by Section 151 of the
Delaware General Corporation Law:

     "RESOLVED, that pursuant to the authority granted to and vested in the
     Board in accordance with the provisions of the Amended and Restated
     Certificate of Incorporation of the Company, as amended (the "Certificate
     of Incorporation"), the Board hereby creates from its authorized class of
     Preferred Stock a series designated as Series A1 Preferred Stock, par value
     $0.001 per share, of the Company;

     RESOLVED FURTHER, that the Board does hereby establish the Series A1
     Preferred Stock as follows:

     Section 1. Designation and Amount.  One (1) share of Preferred Stock of
                ----------------------
     the Company shall be designated as Series A1 Preferred Stock (the "Special
     Series A1 Voting Share").

     Section 2. Dividends and Distributions.  Except as required by applicable
                ---------------------------
     law, neither the holder nor the owner, if different, of the Special Series
     A1 Voting Share shall be entitled to receive any dividends or distributions
     of the Company, whether payable in cash, property or in shares of capital
     stock.

     Section 3. Liquidation.  In the event of any liquidation, dissolution or
                -----------
     winding up of the Company, the holder of the Special Series A1 Voting Share
     shall not be entitled to receive any assets of the Company available for
     distribution to its stockholders.

     Section 4. Voting Rights.  The Special Series A1 Voting Share shall have
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     the following voting rights:

     (A)  with respect to all meetings of stockholders of the Company at which
     holders of the Company's common stock are entitled to vote (each a "Company
     Meeting") and with respect to any written consents, to the extent permitted
     by the Certificate of Incorporation and the Company's By-laws, sought by
     the Company  from its stockholders, including the holders of Company common
     stock (each a

                                       1.
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     "Company Consent"), the Special Series A1 Voting Share shall vote together
     with the common stock of the Company as a single class and the Special
     Series A1 Voting Share shall have the identical voting rights to those of
     the Company's common stock;

     (B)  the holder of the Special Series A1 Voting Share shall be entitled to
     a number of votes equal to the number of exchangeable shares of Siebel
     Janna Arrangement, Inc. (the "Exchangeable Shares") outstanding on the
     record date for determining stockholders entitled to vote at the applicable
     Company Meeting or in connection with the applicable Company Consent, other
     than those held by the Company or its Affiliates (as defined in that
     certain Voting and Exchange Trust Agreement by and among Siebel Janna
     Arrangement, Inc., the Company and Montreal Trust Company of Canada, to be
     dated and entered into on or before the date of issue of the Special Series
     A1 Voting Share, as such agreement may amended, modified or supplemented
     from time to time (the "Trust Agreement"));

     (C)  except as set forth herein, or as otherwise provided by law, the
     registered holders from time to time of Exchangeable Shares shall have no
     special voting rights and their consent shall not be required for taking
     any corporate action; and

     (D)  the voting rights attached to the Special Series A1 Voting Share shall
     terminate pursuant to and in accordance with the Trust Agreement.

     Section 5.  No Redemption.  The Special Series A1 Voting Share shall not
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     be redeemable, except that at such time as no Exchangeable Shares (other
     than the Exchangeable Shares owned by the Company and its Affiliates) shall
     be outstanding, the Special Series A1 Voting Share shall automatically be
     redeemed and canceled.

     Section 6.  Other Provisions.  Pursuant to the terms of the Trust
                 ----------------
     Agreement:

     (A)  during the term of the Trust Agreement, the Company will not issue any
     additional shares of the same series of such Series A1 Preferred Stock
     without the consent of the holders at the relevant time of Exchangeable
     Shares;

     (B)  the votes attached to the Special Series A1 Voting Share shall be
     exercised by the Trustee (as defined in the Trust Agreement) pursuant to
     and in accordance with the Trust Agreement; and

     (C)  the powers, designations, preferences and relative, participating,
     optional and other special rights, and the qualifications, limitations and
     restrictions of the Special Series A1 Voting Share shall be as otherwise
     provided in the Trust Agreement."

                                       2.
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IN WITNESS WHEREOF, this Certificate of Designation is executed on behalf of the
Company by its Senior Vice President, Finance and Administration and Chief
Financial Officer and attested to by its Secretary this 13th day of November,
2000.


                                         SIEBEL SYSTEMS, INC.

                                         By: /s/ Kenneth A. Goldman
                                             ----------------------------------
                                             Kenneth A. Goldman
                                             Senior Vice President, Finance and
                                             Administration and Chief Financial
                                             Officer


ATTEST:

By:  /s/ Jeffrey T. Amann
     ---------------------------
     Jeffrey T. Amann
     Secretary

                                       3.