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                                                                    EXHIBIT 99.1

                            STOCK PURCHASE AGREEMENT


        This Stock Purchase Agreement (the "Agreement") is made and entered into
effective as of the 1st day of September, 2000, by and between WellPoint Health
Networks Inc., a Delaware corporation ("Buyer"), and the California HealthCare
Foundation, a California nonprofit public benefit corporation ("Seller").

                                    RECITALS

        WHEREAS, Seller is the record and beneficial owner of 3,602,800 shares
of common stock (the "Common Stock") of Buyer.

        WHEREAS, Seller desires to sell an aggregate of 602,800 shares of Common
Stock (the "Shares") to Buyer, and Buyer desires to purchase the Shares from
Seller, on the terms and conditions set forth herein.

                                    AGREEMENT

        NOW, THEREFORE, in consideration of the foregoing recitals, the mutual
agreements contained herein, and for other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the parties hereto
agree as follows:

        Section 1. PURCHASE OF SHARES. On the Closing Date (as defined in
Section 2 hereof), Seller hereby agrees to sell, transfer, convey, assign and
deliver to Buyer, and Buyer hereby agrees to purchase, acquire and accept from
Seller, the Shares.

        Section 2. CLOSING DATE; PURCHASE PRICE.

                (a)     The closing date (the "Closing Date") of the purchase
and sale of the Shares shall take place on the third business day following the
date of this Agreement or such different day as Buyer and Seller shall mutually
agree.

                (b)     The purchase price for the Shares (the "Purchase Price")
shall equal $86 15/16 per Share, or an aggregate of $52,405,925 for all of the
Shares.

                (c)     On the Closing Date, and subject to the terms and
conditions set forth in this Agreement, Seller shall deliver a certificate or
certificates representing all of the Shares duly endorsed in blank or
accompanied by stock powers duly executed in blank and in consideration of the
sale, assignment, transfer and delivery of the Shares, Buyer shall pay to Seller
the Purchase Price by wire transfer of immediately available funds to an account
or accounts designated by Seller. In the event that Seller delivers a
certificate or certificates representing a number of shares of Common Stock
greater than the Shares, Buyer shall promptly thereafter issue to Seller a
certificate representing the number of shares by which the certificate or
certificates delivered by Seller

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exceeded the number of Shares.

        Section 3. REPRESENTATIONS AND WARRANTIES OF SELLER. Seller represents
and warrants to Buyer that:

                (a)     Seller has all requisite corporate power and authority
to enter into this Agreement and to consummate the transactions contemplated
hereby.

                (b)     This Agreement has been duly executed and delivered by
Seller, has been effectively authorized by all necessary action, and constitutes
the legal, valid and binding obligation of Seller, enforceable against Seller in
accordance with its terms, except as such enforceability may be limited by laws
relating to bankruptcy, insolvency, reorganization or other laws relating to
creditors' rights generally or by general principles of equity.

                (c)     Seller has good and marketable title to the Shares, free
and clear of all security interests, covenants, conditions, restrictions,
pledges, liens, charges, encumbrances, options and adverse claims or rights of
any kind whatsoever, other than pursuant to the Amended and Restated Voting
Trust Agreement dated as of August 4, 1997 (as amended by that Amendment No. 1
dated as of June 12, 1998). Assuming Buyer has no notice of any adverse claim,
Buyer shall acquire from Seller as of the Closing Date good and marketable title
to the Shares, free and clear of all security interests, covenants, conditions,
restrictions, pledges, liens, charges, encumbrances, options and adverse claims
or rights of any kind whatsoever.

                (d)     The execution and delivery of this Agreement by Seller
and the consummation by Seller of the transactions contemplated hereby do not
and will not result in a breach of any of the terms or provisions of, or
constitute a default under, or conflict with (i) the articles of incorporation
or bylaws of Seller, (ii) any material agreement to which Seller is a party or
by which it is bound, (iii) any judgment, decree, order or award of any court,
governmental body or arbitrator by which Seller is bound or (iv) any material
Federal or State law, rule or regulation applicable to Seller or its property.

                (e)     No broker or finder has acted for Seller in connection
with this Agreement or the transactions contemplated hereby, and no broker or
finder is entitled to any brokerage or finder's fees or other commissions in
respect of such transactions.

                (f)     In connection with Seller's sale of the Shares, Seller
has had the opportunity to ask Buyer any and all relevant questions regarding,
among other things, the business and operations of Buyer and Seller has received
answers from the Buyer which the Seller considers to be reasonably responsive
and adequate to such questions. The Seller has, to the extent deemed necessary
by the Seller, consulted with the Seller's advisors (including the Seller's
attorney, accountant or investment advisors) regarding the sale of the Shares to
Buyer. The Seller understands and acknowledges that events or circumstances may
occur after the date hereof or after the Closing Date that may be favorable or
unfavorable to the Buyer's earnings, business affairs or operations, and that
such events or circumstances may result in changes in the fair market value of
the Common


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Stock.

        Section 4. REPRESENTATION AND WARRANTIES OF BUYER. Buyer represents and
warrants to Seller that:

                (a)     Buyer has all requisite corporate power and authority to
enter into this Agreement and to consummate the transactions contemplated
hereby.

                (b)     This Agreement has been duly executed and delivered by
Buyer, has been effectively authorized by all necessary action, and constitutes
the legal, valid and binding obligation of Buyer, enforceable against Buyer in
accordance with its terms, except as such enforceability may be limited by laws
relating to bankruptcy, insolvency, reorganization or other laws relating to
creditors' rights generally or by general principles of equity.

                (c)     The execution and delivery of this Agreement by Buyer
and the consummation by Buyer of the transactions contemplated hereby do not and
will not result in a breach of any of the terms or provisions of, or constitute
a default under, or conflict with (i) the certificate of incorporation or bylaws
of Buyer, (ii) any material agreement to which Buyer is a party or by which it
is bound, (iii) any judgment, decree, order or award of any court, governmental
body or arbitrator by which Buyer is bound or (iv) any material Federal or State
law, rule or regulation applicable to Buyer or its property.

                (d)     No broker or finder has acted for Buyer in connection
with this Agreement or the transactions contemplated hereby, and no broker or
finder is entitled to any brokerage or finder's fee or other commissions in
respect of such transactions.

        Section 5. CONDITIONS TO CLOSING.

                (a)     BUYER'S CONDITION. Buyer's obligations to consummate the
transactions contemplated by this Agreement shall be subject to the
representations and warranties of Seller contained herein being true and correct
at and as the Closing Date as if made at and as of such time.

                (b)     SELLER'S CONDITION. Seller's obligation to consummate
the transactions contemplated by this Agreement shall be subject to the
representations and warranties of Buyer contained herein being true and correct
at and as of the Closing Date as if made at and as of such time.

        Section 6. TERMINATION. This Agreement may be terminated at any time on
or prior to the Closing Date by mutual written consent of Seller and Buyer. In
addition, either party may terminate this Agreement at any time on or after the
Closing Date provided for in Section 2 in the event that the other party hereto
fails to comply in any material respect with its obligations hereunder. In the
event this Agreement is terminated pursuant to this Section 6, this Agreement
shall terminate without any liability or further obligation of either party to
the other.

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        Section 7. NOTICES. All notices and other communication hereunder shall
be in writing and shall be deemed given if delivered personally or by facsimile
or three business days following being mailed by certified or registered mail,
postage prepaid, return-receipt requested, address as follows:

If to Seller:             California HealthCare Foundation
                          476 Ninth Street
                          Oakland, California 94607
                          Attention: President
                          Facsimile: (510) 238-1388

If to the Buyer:          WellPoint Health Networks Inc.
                          1 WellPoint Way
                          Thousand Oaks, California 91362
                          Attention: General Counsel
                          Facsimile: (805) 557-6820

        Section 8. SUCCESSORS AND ASSIGNS. This Agreement shall inure to the
benefit of and be binding upon the parties hereto and their respective
successors and assigns.

        Section 9. GOVERNING LAW. This Agreement shall be governed by, and
construed and enforced in accordance with, the laws of the State of Delaware,
without reference to choice or conflict of law principles thereof.

        Section 10. COUNTERPARTS. This Agreement may be executed simultaneously
in one or more counterparts, each of which shall be deemed an original, but all
of which together shall constitute one and the same instrument.

        Section 11. ENTIRE AGREEMENT. This Agreement contains the entire
Agreement between the parties hereto with respect to the transactions
contemplated herein and supersedes all previous oral and written, and all
contemporaneous oral negotiations, commitments and understandings.

        Section 12. SEVERABILITY. Any provision of this Agreement that is
invalid, illegal or unenforceable in any jurisdiction shall, as to that
jurisdiction, be ineffective to the extent of such invalidity, illegality or
unenforceability, without affecting in any way the remaining provisions hereof
in such jurisdiction or rendering that or any other provision or this Agreement
invalid, illegal or unenforceable in any other jurisdiction.

        Section 13. EXPENSES. Seller, on the one hand, and Buyer, on the other
hand, shall pay their respective fees and expenses incurred by them in
connection with the transactions contemplated herein.

        Section 14. FURTHER ASSURANCES. Each of Seller and Buyer agrees promptly
to execute and

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deliver such documents and to do such other acts as are reasonably necessary
appropriate to effectuate the purposes of this Agreement.

        IN WITNESS WHEREOF, each of the parties hereto have caused this
Agreement to be executed as of the date first above written.

         SELLER:           CALIFORNIA HEALTHCARE FOUNDATION

                                    By:     /s/ CRAIG ZIEGLER
                                            --------------------------------
                                    Its:    Chief Financial Officer
                                            --------------------------------

         BUYER:            WELLPOINT HEALTH NETWORKS INC.

                                    By:     /s/ DAVID COLBY
                                            --------------------------------
                                    Its:    Chief Financial Officer
                                            --------------------------------


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