<PAGE>
                                                                     EXHIBIT 4.2

                                   ADVANCEPCS

                                WARRANT AGREEMENT

         This Warrant Agreement (this "Agreement") dated as of January 2, 2001
is entered into by and between AdvancePCS f/k/a Advance Paradigm, Inc., a
Delaware corporation (the "Company") and Wellmark, Inc., an Iowa mutual
insurance company ("Client").

                               TERMS OF AGREEMENT

         NOW THEREFORE, in consideration of the premises and the mutual
covenants herein contained, the Company and Client hereby agree as follows:

         Section 1. PHARMACEUTICAL SERVICE AGREEMENT. Reference is made to that
certain Managed Pharmacy Benefit Services Agreement dated January 1, 1998, as
amended, entered into by and between the Company and Client (the "Services
Agreement"). Capitalized terms not otherwise defined herein shall have the
meanings given to them in the Services Agreement.

         Section 2. GRANT OF THE RIGHT TO PURCHASE COMMON STOCK. The Company
hereby grants to Client the right, and Client shall be entitled, subject to the
terms and conditions hereinafter set forth, to purchase from the Company
Fifty-Six Thousand Two Hundred Fifty (56,250) shares of its common stock, par
value $0.01 per share (the "Common Stock") set forth below (which number is
referred to herein as the "Initial Exercise Number") at a per share exercise
price equal to $ 39.50 per share (the "Exercise Price"). The right to purchase
such shares shall be evidenced by five (5) warrant certificates in the form of
Exhibit A hereto with each warrant certificate representing the right to
purchase 20% of the Initial Exercise Number. The Initial Exercise Number and
Exercise Price of such shares are subject to adjustment as provided in Section 4
hereof.

         Section 3. EXERCISE OF WARRANT. The purchase rights represented by the
warrant certificate shall vest in consecutive years, with the right to exercise
the first warrant certificate vesting on July 1, 2001 and the right to exercise
each of the other warrant certificates vesting on each July 1 thereafter (each a
"vesting date") and will be cumulative. Each warrant certificate may be
exercised only so long as the Company is the exclusive vendor of pharmacy
benefit management services for Client in accordance with Section 13 of the
Services Agreement. If the Services Agreement is terminated for any reason, the
vesting schedule will terminate at that time as well and only that portion of
the warrant which had vested prior to the date of termination will be considered
vested and exercisable; provided, however, that the Company has the right, in
its sole discretion, to accelerate the vesting of the warrant in accordance with
Section 9(a)(ii)(A) of the Services Agreement. Except as otherwise provided for
herein, the term of this Warrant Agreement and the right to purchase Common
Stock as described herein shall commence on July 1, 2001 and will end on July 1,
2006 (the "Exercise Period"). No warrant certificate shall be exercisable after
the expiration of the Exercise Period. Shares of Common Stock purchased upon
exercise of each warrant certificate shall at the time of purchase be paid for
in full. To the extent that the right to purchase shares under any warrant
certificate has vested hereunder, such warrant



<PAGE>

certificate may be exercised by written notice to the Company in the form
attached to such warrant certificate, which specifies an exercise date (the
"Date of Exercise"), accompanied by full payment for the shares by wire transfer
or certified or official bank check or the equivalent thereof acceptable to
Company. Upon the exercise of the initial warrant certificate, Client and the
Company shall execute and enter into the Stockholders Agreement attached hereto
as Exhibit B (the "Stockholders Agreement").

         At the time of delivery, the Company shall, without stock transfer tax
to the warrant certificate holder, deliver to such holder (or to such other
person) at the principal office of the Company, or such other place as shall be
mutually agreed upon, a certificate or certificates for such shares, provided,
however, that the time of delivery may be postponed by the Company for such
period as may be required for it with reasonable diligence to comply with any
requirements of law. The Company at the time of exercise will require in
addition that the registered owner of the Common Stock deliver an executed copy
of the Stockholder Agreement, an investment representation in form acceptable to
the Company, and the Company will place a legend on the certificate for such
Common Stock restricting the transfer of same. At no time shall the Company have
any obligation or duty to register under the Securities Act of 1933 (the "1933
Act") the Common Stock issuable upon exercise of warrant.

         Section 4. ADJUSTMENTS TO EXERCISE PRICE AND NUMBER OF SHARES. The
Exercise Price and number of shares of Common Stock purchasable pursuant to the
exercise of each warrant certificate shall be subject to adjustment from time to
time as follows:

         (a) Adjustment for Combinations or Consolidations of Common Stock. In
the event the Company, at any time or from time to time after the date hereof,
effects a subdivision or capital reorganization of its outstanding Common Stock
for a greater or lesser number of shares, then and in each such event the
Initial Exercise Number and the Exercise Price shall be adjusted proportionately
such that Client is entitled to purchase the same percentage of all shares of
the Company's outstanding capital stock then issued and issuable for the same
aggregate consideration as such warrant certificate holder was entitled to
purchase immediately prior to such event.

         (b) Adjustment for Certain Dividends and Distributions. In the event
the Company at any time or from time to time after the date hereof shall pay a
dividend payable in Common Stock of the Company, or otherwise make a
distribution of Common Stock to its stockholders, then the Exercise Price shall
be adjusted, from and after the record date of such dividend or the date of such
distribution, to that price determined by multiplying the Exercise Price by a
fraction,

                  (i) the numerator of which shall be the total number of shares
                  of capital stock issued and outstanding or deemed to be issued
                  and outstanding immediately prior to the time of such issuance
                  or the close of business on such record date; and

                  (ii) the denominator of which shall be the number of shares of
                  capital stock issued and outstanding or deemed to be issued
                  and outstanding immediately prior to the time of such issuance
                  or the close of business on such record date plus the number
                  of shares of capital stock to be issued;

                                       2
<PAGE>

         provided, however, that if such record date shall have been fixed and
such dividend is not fully paid or if such distribution is not fully made on the
date fixed therefor, the Exercise Price shall be recomputed accordingly as of
the close of business on such record date or date of distribution and thereafter
the Exercise Price shall be adjusted pursuant to this Section 4(b) as of the
time of actual payment of such dividend or distribution. Client shall thereafter
be entitled to purchase, at the Exercise Price resulting from such adjustment,
the number of shares of Common Stock (calculated to the nearest whole share)
obtained by multiplying the Exercise Price in effect immediately prior to such
adjustment by the number of shares of Common Stock issuable upon the exercise
hereof immediately prior to such adjustment and dividing the product thereof by
the Exercise Price resulting from such adjustment.

         (c) Number of Shares. Upon any adjustment of the Exercise Price in
accordance with Section 4(b), Client shall thereafter (until another such
adjustment) be entitled to purchase, at the new Exercise Price, the number of
shares, calculated to the nearest full share, obtained by multiplying the
Exercise Price in effect immediately prior to such adjustment by the number of
shares purchasable pursuant hereto immediately prior to such adjustment and
dividing the product thereof by the new Exercise Price resulting from such
adjustment.

         Section 5. RESERVATION AND AUTHORIZATION OF COMMON STOCK. The Company
shall at all times reserve and keep available, free from preemptive rights, out
of its authorized but unissued Common Stock, solely for the purposes of
effecting the exercise of all outstanding warrant certificates, the full number
of shares of Common Stock issuable upon the exercise of all outstanding warrant
certificates. For the purpose of this Section 5, the full number of shares of
Common Stock issuable upon the exercise of all outstanding warrant certificates
shall be computed as if at the time of computation of such number of shares of
Common Stock all outstanding warrant certificates were held by a single holder.
The Company shall from time to time, in accordance with applicable law, increase
the authorized amount of its Common Stock if at any time the authorized amount
of its Common Stock remaining unissued shall not be sufficient to permit the
exercise of all warrant certificates at the time outstanding.

         Section 6. TRANSFERABILITY.

         (a) The warrant certificates are not transferable by Client except to
the Company or affiliates of Client. Any permitted transfer of a warrant
certificate shall be recorded on the books of the Company upon receipt by the
Company of a notice of transfer in the form attached hereto as Exhibit B, at its
principal offices and the payment to the Company of all transfer taxes and other
governmental charges imposed on such transfer. The shares of Common Stock
purchased by Client are not transferable except as provided in the Stockholders
Agreement.

         (b) Unless and until otherwise permitted by this Section and the
Stockholders Agreement, each certificate representing Common Stock initially
issued upon the exercise of each warrant certificate (a "Stock Certificate"),
and each certificate for Common Stock issued to any subsequent transferee of any
such certificate, shall be stamped or otherwise imprinted with a legend in
substantially the following form:

                  "THE SECURITIES EVIDENCED BY THIS CERTIFICATE HAVE NOT BEEN
                  REGISTERED UNDER THE SECURITIES ACT OF 1933 AND MAY



                                       3
<PAGE>

                  BE REOFFERED AND SOLD ONLY IF SO REGISTERED OR IF AN EXEMPTION
                  FROM SUCH REGISTRATION IS AVAILABLE. THE SECURITIES
                  REPRESENTED BY THIS CERTIFICATE ARE ALSO SUBJECT TO ADDITIONAL
                  RESTRICTIONS ON TRANSFER, CERTAIN REPURCHASE OPTIONS AND
                  CERTAIN OTHER AGREEMENTS SET FORTH IN A STOCKHOLDER AGREEMENT
                  BETWEEN THE COMPANY AND CLIENT, DATED AS OF <DATE>, A COPY OF
                  WHICH MAY BE OBTAINED BY THE HOLDER HEREOF AT THE COMPANY'S
                  PRINCIPAL PLACE OF BUSINESS WITHOUT CHARGE."

                  Prior to any permitted transfer of a warrant certificate or
any Stock Certificate, the holder thereof shall furnish, at the expense of such
holder, to the Company an opinion of counsel, reasonably satisfactory in form
and substance to the Company, to the effect that such transfer is exempt from
registration under the Securities Act. Upon any exercise of any warrant
certificate for shares of Common Stock to be registered in the name of a person
other than Client, Client shall furnish, at the expense of Client, to the
Company an opinion of counsel (which may be the General Counsel of Client),
reasonably satisfactory in form and substance to the Company, to the effect that
the issuance of the shares of Common Stock to such other person upon exercise of
the warrant certificate is exempt from registration under the Securities Act.

         Section 7. FRACTIONAL SHARES. The Company shall not be required to
issue a fractional share of stock upon any exercise of a warrant certificate. As
to any final fraction of a share that Client would otherwise be entitled to
purchase upon exercise of a warrant certificate, the Company shall, if it does
not issue a fractional share, pay a cash adjustment in respect of such final
fraction in an amount equal to the same fraction of the Exercise Price per share
of Common Stock.

         Section 8. EXCHANGE AND REPLACEMENT OF WARRANT. In the event of loss,
theft or destruction of a warrant certificate, the Company will make and deliver
a new warrant certificate of like tenor, in lieu of such warrant certificate,
upon receipt by the Company of evidence reasonably satisfactory to it of such
loss, theft, or destruction and indemnity or security reasonably satisfactory to
it, and reimbursement to the Company of all reasonable expense incidental
thereto. In the case of mutilation of a warrant certificate and upon surrender
and cancellation of such warrant certificate, the Company will make and deliver
a new warrant certificate of like tenor, in lieu of such warrant certificate.

         Section 9. RIGHTS PRIOR TO EXERCISE OF WARRANT. Prior to the initial
exercise of a warrant certificate, Client shall not be entitled to any rights of
a stockholder of the Company with respect to the Common Stock for which such
warrant certificate may then be exercisable, including without limitation the
right to vote, to receive dividends or other distributions or to exercise any
preemptive rights and shall not be entitled to receive any notice of any
proceedings of the Company except as provided herein.

         Section 10. AUTHORIZATION AND ISSUANCE. The Company represents and
warrants to Client that it has the corporate power and authority to issue the
warrant certificates; the warrant certificates have been duly authorized,
executed and delivered and are duly and validly issued, fully paid and
nonassessable; the issuance of the warrant certificates, and the shares of


                                       4
<PAGE>

Common Stock issuable upon their exercise, are not prohibited or restricted by
the Certificate of Incorporation or Bylaws of the Company or any material
agreement to which the Company is a party; except for those agreements for which
the Company has received the requisite consents or waivers; and the shares of
Common Stock issuable upon exercise of the warrant certificates, when issued
upon exercise of the warrant certificates pursuant to the terms hereof, will be
duly and validly issued, fully paid and nonassessable. The Company will not, by
amendment to its Articles of Incorporation or Bylaws or through reorganization,
merger, sale of assets or otherwise, avoid or seek to avoid its performance
hereunder.

         Section 11. REPRESENTATIONS AND COVENANTS OF CLIENT. This Warrant
Agreement has been entered into by the Company in reliance upon the following
representations and covenants of Client:

         (a) Investment Purpose. The right to acquire the Common Stock issuable
upon exercise of Client's rights contained herein will be acquired for
investment and not with a view to the sale or distribution of any part thereof,
and Client has no present intention of selling or engaging in any public
distribution of the same except pursuant to a registration or exemption.

         (b) Private Issue. Client understands (i) that the Common Stock
issuable upon exercise of the warrant certificates is not registered under the
1933 Act or qualified under applicable state securities laws on the ground that
the issuance contemplated by this Warrant Agreement will be exempt from the
registration and qualifications requirements thereof, and (ii) that the
Company's reliance on such exemption is predicated on the representations set
forth in this Section 11.

         (c) Financial Risk. Client has such knowledge and experience in
financial and business matters as to be capable of evaluating the merits and
risks of its investment, and has the ability to bear the economic risks of its
investment.

         (d) Risk of No Registration. Client understands that if the Company
does not register with the Securities and Exchange Commission pursuant to
Section 11 of the 1933 Act, or file reports pursuant to Section 15(d) of the
Securities Exchange Act of 1934 (the "1934 Act"), or if a registration statement
covering the securities under the 1933 Act is not in effect when it desires to
sell the Common Stock issuable upon exercise of the right to purchase, it may be
required to hold such securities for an indefinite period. Client also
understands that any sale of its rights to purchase Common Stock which might be
made by it in reliance upon Rule 144 under the 1933 Act may be made only in
accordance with the terms and conditions of that Rule.

         (e) Stockholders Agreement. Prior to the exercise of any warrant
certificate, Client agrees to, and to cause any permitted transferee to, enter
into, execute and perform the Stockholders Agreement.

         Section 12. GENERAL.

         (a) Expenses. Each party shall bear and pay all costs and expenses
incurred by them respecting the transactions contemplated herein and all
investigations and proceedings in connection therewith, including, without
limitation, fees, commissions or expenses of their respective counsel,
accountants and financial advisors.


                                       5
<PAGE>

         (b) Notice. Any notice required to be given pursuant to the terms and
provisions of this Agreement shall be in writing and shall be sent by certified
mail, return receipt requested, or by overnight delivery service, or facsimile
transmission confirmed by telephone and followed by overnight delivery to the
parties at the addresses below or such other address as shall be specified by
the parties by like notice

                               to the Company at:

                                   AdvancePCS
                             Attn: Legal Department
                      5215 North O'Connor Blvd., Suite 1600
                               Irving, Texas 75039
                              Fax No.: 972/830-6008

                                and to Client at:

                                 Wellmark, Inc.
                              Attn. Kevin Van Dyke
                                636 Grand Avenue
                             Des Moines, Iowa 50309
                              Fax No.: 515/245-6000

                  Notice so given shall, in the case of notice so given by mail,
be deemed to be given and received on the fourth calendar day after posting, in
the case of notice so given by express delivery service, on the date of actual
delivery and, in the case of notice so given by facsimile transmission or
personal delivery, on the date of actual transmission or personal delivery, as
the case may be.

         (c) Binding Nature and Assignment. This Agreement shall be binding upon
and inure to the benefit of the parties hereto and their successors and assigns.
Neither party may assign this Agreement without the prior written consent of the
other; provided, however, that either party may transfer or assign its rights
and obligations under this Agreement, to any affiliate, and provided further
that no such assignment shall have the effect of releasing such party from any
of its obligations under this Agreement.

         (d) Headings and Interpretation. The headings of the various sections
of this Agreement are inserted for convenience only and do not, expressly or by
implication, limit, define or extend the specific terms of the section so
designated.

         (e) Governing Law. The validity, enforceability, and interpretation of
this Agreement shall be determined and governed by the internal laws of the
State of Texas (and not the law of conflicts).

         (f) Entire Agreement. This Agreement and those documents expressly
referred to herein contain all the terms and conditions agreed upon by the
parties, and supersedes all prior




                                       6
<PAGE>

understandings, writings, proposals, representations, or communications, oral or
written, of the parties hereto.

         (g) Authority. Company and Client warrant that each has full power and
authority to enter into and perform this Agreement, and the person signing this
Agreement on behalf of each party certifies that such person has been properly
authorized and empowered to enter into this Agreement on behalf of such party.

         (h) Non-Waiver. The failure of either party to insist, in any one or
more instances, upon performance of any of the terms, covenants or conditions of
this Agreement shall not be construed as a waiver or a relinquishment of any
right or claim granted or arising hereunder or of the future performance of any
such term, covenant, or condition, and such failure shall in no way affect the
validity of this Agreement or the rights and obligations of the parties
hereunder.

         (i) Survival. Should any part, term or condition of this Agreement be
declared illegal or unenforceable or in conflict with any other laws, the
remaining provisions shall be valid and not affected thereby.

         (j) Counterparts. This Agreement may be executed in any number of
counterparts, each of which shall be deemed an original and all of which taken
together shall constitute one and the same instrument.

         (k) Further Assurances. From time to time upon request and without
further consideration, the parties hereto shall, and shall cause their
subsidiaries and affiliates, to execute, deliver or acknowledge such documents
and do such further acts as the other party hereto may reasonably require to
effectuate its obligations contemplated by this Agreement.


         IN WITNESS WHEREOF, the parties have caused this Agreement to be
executed and delivered by their proper and duly authorized officers on the date
first above written. By executing the Agreement, the undersigned individuals
hereby warrant and represent that they have read this Agreement in its entirety
and agree to all its terms.


                                             ADVANCEPCS


                                             By: /s/ DAVID D. HALBERT
                                                --------------------------------
                                                David D. Halbert
                                                Chairman of the Board and
                                                Chief Executive Officer


                                               WELLMARK, INC.

                                             By: /s/ ERIC L. BOOK
                                                --------------------------------
                                             Name:   Eric L. Book
                                                   -----------------------------
                                             Title:  Group Vice President,
                                                     Health Management, and
                                                     Chief Medical Officer
                                                   -----------------------------


                                       7
<PAGE>

                                    EXHIBITS



                           Exhibit A                 Warrant Certificate

                           Exhibit B                 Stockholders Agreement








                                       8
<PAGE>



                                    EXHIBIT A

THIS WARRANT CERTIFICATE AND THE UNDERLYING SHARES HEREOF HAVE NOT BEEN
REGISTERED UNDER THE SECURITIES ACT OF 1933 AND MAY NOT BE SOLD OR TRANSFERRED
UNLESS THERE IS AN EFFECTIVE REGISTRATION STATEMENT UNDER SUCH ACT COVERING SUCH
SECURITIES OR THE COMPANY RECEIVES AN OPINION OF COUNSEL (WHICH MAY BE COUNSEL
FOR THE COMPANY) STATING THAT SUCH SALE OR TRANSFER IS EXEMPT FROM THE
REGISTRATION AND PROSPECTUS DELIVERY REQUIREMENTS OF SUCH ACT.

                     For Purchase of Shares of Common Stock
                                       of
                                   AdvancePCS

                                  July 1, 2001

         THIS CERTIFIES THAT Wellmark, Inc. ("Client"), or registered
transferees or assigns, is entitled, subject to the terms and conditions set
forth in this warrant certificate, to purchase from AdvancePCS, a Delaware
corporation (the "Company"), 11,250 (the "Exercise Number") fully paid and
nonassessable shares of Common Stock, $0.01 par value per share, of the Company
(the "Common Stock"), at any time during the Exercise Period upon payment in
full of the Exercise Price. The Initial Exercise Number and Exercise Price shall
be subject to adjustment as set forth in the Warrant Agreement referred to
below. This warrant certificate is issued pursuant to a Warrant Agreement
between Client and the Company dated as of January 2, 2001 (the "Warrant
Agreement"), and is subject to all the terms thereof, including the limitations
on transferability set forth therein. Capitalized terms used herein as defined
terms but not otherwise defined shall have the meaning assigned to such term in
the Warrant Agreement.

         This warrant certificate may be exercised, by the holder hereof, for
all shares of Common Stock covered hereby, by the presentation and surrender of
this warrant certificate together with the duly executed Election to Purchase in
the form attached as hereto, at the principal office of the Company (or at such
other address as the Company may designate by notice in writing to the holder
hereof at the address of such holder appearing on the books of the Company), and
upon payment to the Company of the Exercise Price and execution of the
Stockholders Agreement as set forth in the Warrant Agreement.

         IN WITNESS WHEREOF, the Company has caused this warrant certificate to
be duly executed and delivered by its duly authorized officer as an instrument
under seal as of the date of first above written.

                                                AdvancePCS


                                                By:
                                                  -----------------------------
                                                  David D. Halbert
                                                  Chairman of the Board and
                                                  Chief Executive Officer


                                       9
<PAGE>






                              ELECTION TO PURCHASE


TO:  AdvancePCS (the "Company")

         The undersigned, owner of the accompanying warrant certificate hereby
irrevocably exercises the option to purchase ________ shares of Common Stock in
accordance with the terms of such warrant certificate, directs that the shares
issuable and deliverable upon such purchase (together with any check for a
fractional interest) be issued in the name of and delivered to the undersigned,
and makes payment in full therefor at the Exercise Price provided or referenced
in such warrant certificate.

COMPLETE FOR REGISTRATION OF SHARES OF COMMON STOCK ON THE STOCK TRANSFER
RECORDS MAINTAINED BY THE COMPANY:


--------------------------------------------------------------------------------
Name of Warrant Certificate Holder

--------------------------------------------------------------------------------
Address

--------------------------------------------------------------------------------
Federal ID Tax Number or Social Security Number

--------------------------------------------------------------------------------
Date of Exercise (must be at least fifteen days after the date of this Notice)

                                                     Wellmark, Inc.

                                                     ---------------------------
                                                     Signature

                                                     ---------------------------
                                                     Title

                                                     ---------------------------
                                                     Date





                                       10
<PAGE>



                                    EXHIBIT B
                              STOCKHOLDER AGREEMENT

         This Stockholder Agreement dated as of ___________, by and among
Wellmark, Inc. an Iowa mutual insurance company (the "STOCKHOLDER"), and
AdvancePCS, a Delaware corporation (the "COMPANY").


                             PRELIMINARY STATEMENTS

         Pursuant to the terms and conditions of the Warrant Agreement, dated as
of January 2, 2001, by and between the Company and Stockholder, the Company
agreed to issue five (5) warrant certificates to acquire shares of the Company's
common stock, par value $.01 per share (the "COMMON STOCK"). Pursuant to the
terms of the Warrant Agreement, the Stockholder agreed to execute and enter into
this Agreement prior to the issuance of any shares of Common Stock thereunder.

         NOW THEREFORE, in consideration of the premises and the mutual
agreements contained herein and for other good, valuable and binding
consideration, the receipt and sufficiency of which are hereby acknowledged, the
parties hereto, intending to be legally bound, hereby agree as follows:


                             STATEMENT OF AGREEMENT

1. Restricted Stock. The terms and conditions of this Agreement shall apply to
all shares of Common Stock issued to Stockholder pursuant to the Warrant
Agreement (the "STOCK").

2. Restrictions on Transfers.

         2.1 Transfers to Affiliate.

         (a) Transfers to Affiliates. Stockholder shall be entitled to transfer
the Stock held by it to entities that directly or indirectly control, are
controlled by, or are under common control with Stockholder (each, an
"AFFILIATE"), provided that any such Affiliates first deliver to the Company
their written acknowledgment of, and agreement to be bound by, the terms and
provisions contained in this Agreement; and the Stockholder delivers to the
Company an opinion of counsel, reasonably acceptable in form and substance to
the Company and its counsel, that registration under the Securities Act is not
required in connection with such transfer. The foregoing notwithstanding,
Stockholder shall not, without the prior written consent of the Company which
consent will not be unreasonably withheld, transfer any shares of Stock to any
Affiliate, nor any officer, director, employee or holder of debt or equity in
any Affiliate that is primarily engaged in the business of pharmacy benefit
management services, pharmacy network management, pharmacy claims adjudication,
mail service pharmacy, pharmacy clinical services and/or the manufacture of
drugs, biotech products or biologicals.



                                       11
<PAGE>

         (b) Affiliates' Proxy. In the event that Stockholder transfers less
than all of its Stock pursuant to Section 2.1(a), Stockholder shall exercise all
of the rights inuring under this Agreement with respect to such transferred
Stock and the transferees shall grant Stockholder proxies to exercise such
rights. In the event that Stockholder transfers all of its Stock pursuant to
Section 2.1(a), one such transferee reasonably acceptable to the Company shall
be designated by Stockholder to exercise all rights inuring under this Agreement
with respect to such Stock and the other transferees shall grant such designated
transferee proxies to exercise such rights.

         2.2 Restrictions on Third Party Transfers of the Stock.

         (a) General. During the first two years following the date the Stock is
issued the ("ISSUANCE DATE"), Stockholder agrees that it will not sell, pledge
or otherwise transfer any interest in any shares of the Stock to any party that
is not an Affiliate, without the prior written consent of the Company. At any
time after the second anniversary of the Issuance Date, the Stockholder may
sell, pledge or otherwise transfer shares of the Stock to third parties ("THIRD
PARTY TRANSFER"); provided that such transfer is in accordance with this Section
2.2, and provided further that the transferring Stockholder delivers to the
Company an opinion of counsel, reasonably acceptable in form and substance to
the Company and its counsel, that registration under the Securities Act is not
required in connection with such transfer. The foregoing notwithstanding,
Stockholder agrees that it shall not transfer any shares of Stock to any person
or entity, nor any officer or director in any entity that is primarily engaged
in the business, or has an affiliate engaged in the business of pharmacy benefit
management services, pharmacy network management, pharmacy claims adjudication,
mail service pharmacy, pharmacy clinical services, and/or pharmacy outcomes
management, or the manufacture of drugs, biotech products or biologicals without
the prior written consent of the Company.

         (b) Sale Notice. At least 30 days prior to making any Third Party
Transfer under Section 2.2(a), the transferring Stockholder will deliver a
written notice (the "SALE NOTICE") to the Company. The Sale Notice will disclose
in reasonable detail the identity of the prospective transferee(s) and the terms
and conditions of the proposed transfer. Stockholder agrees not to consummate
any such transfer until 30 days after the Sale Notice has been delivered to the
Company.

         (c) Non-Cash Consideration. In the event the consideration for the
Stock as disclosed in the Sale Notice is other than cash, a promissory note or a
combination thereof, the price for the Stock shall be the value of that
consideration as agreed to by the transferring Stockholder and the Company, or,
if no agreement can be reached as to the valuation of such consideration, the
fair market value of such consideration as determined by two appraisers (one
appointed by the Stockholder and one appointed by the Company). In the event the
two appraisers are unable to agree on a fair market value within 10 days after
they are appointed, the fair market value of the consideration shall be the
average of the appraised values of the two appraisers; provided, however, that
if the appraised values of the two appraisers differ by more than five percent
(5%) of the higher of the two appraised values, the two respective appointed
appraisers shall select a third appraiser who shall independently, within 10
days after this appointment, make a determination of the value of the
consideration and the average of the appraised values of the three appraisers
shall be the purchase price and shall be binding on the parties hereto. The
transferring Stockholder and the Company shall each bear the cost of their
respective appraisers



                                       12
<PAGE>

and shall share the cost equally of the third appraiser, if any. Notwithstanding
anything herein to the contrary, if an appraisal is used to determine the value
of the consideration pursuant to this Section 2.2(c), the time periods provided
for in Section 2.2(b) shall be tolled from the time of the initial appointment
of the two appraisers until a final appraised value is determined pursuant to
this Section 2.2(c).

         (d) Public Sale. Notwithstanding the foregoing, at any time after the
first anniversary of the Issuance Date, the Stockholder may sell, pledge or
otherwise transfer shares of the Stock to the public in a market transaction
without complying with the restrictions set forth in Section 2.2(b) and (c).

         2.3 Legend. The certificates representing the Stock will bear the
following legend:

                  "THE SECURITIES EVIDENCED BY THIS CERTIFICATE HAVE NOT BEEN
                  REGISTERED UNDER THE SECURITIES ACT OF 1933 AND MAY BE
                  REOFFERED AND SOLD ONLY IF SO REGISTERED OR IF AN EXEMPTION
                  FROM SUCH REGISTRATION IS AVAILABLE. THE SECURITIES
                  REPRESENTED BY THIS CERTIFICATE ARE ALSO SUBJECT TO ADDITIONAL
                  RESTRICTIONS ON TRANSFER, CERTAIN REPURCHASE OPTIONS AND
                  CERTAIN OTHER AGREEMENTS SET FORTH IN A STOCKHOLDER AGREEMENT
                  BETWEEN THE COMPANY AND WELLMARK, INC., DATED AS OF [DATE], A
                  COPY OF WHICH MAY BE OBTAINED BY THE HOLDER HEREOF AT THE
                  COMPANY'S PRINCIPAL PLACE OF BUSINESS WITHOUT CHARGE."

         Any legend endorsed on a certificate pursuant to Section 2.3 hereof and
the stop transfer instructions and record notations with respect thereto shall
be removed and the Company shall issue a certificate without such legend to the
holder thereof at such time as the securities evidenced thereby cease to be
restricted securities

         2.4 Extraordinary Transaction. In the event of a merger of the Company
with a third party where the Company is not the surviving entity, sale of a
majority of the capital stock of the Company, or the sale of all or
substantially all of its assets ("EXTRAORDINARY TRANSACTION"), the Stock shall
be entitled to receive the same benefits as the holders of the Common Stock will
receive in the Extraordinary Transaction. The Stockholder agrees to consent to
and execute all required documents in connection with the Extraordinary
Transaction.

         2.5 Limitation on Stock Holdings. The Stockholder agrees that in no
event, shall it, either independently or together with its Affiliates, own
Common Stock or rights to acquire Common Stock, that represent, or if converted
to Common Stock would represent, more than ten percent (10%) of the Company's
issued and outstanding Common Stock, without the Company's prior written
consent.



                                       13
<PAGE>

3. Notices.

         All notices and other communications hereunder shall be in writing and
shall be deemed to have been duly given if delivered personally, mailed by
certified mail (return receipt requested) or sent by express delivery service,
or facsimile transmission (confirmed by telephone conversation and followed by
overnight delivery) to the parties at the following addresses or at such other
addresses as shall be specified by the parties by like notice:


                           if to the Company:

                           AdvancePCS
                           Attn: Legal Department
                           5215 North O'Connor Blvd.
                           Suite 1600
                           Irving, Texas  75039
                           Fax No.:  (972) 830-6008

                           if to Stockholder:

                           Wellmark, Inc.
                           Attn:  Kevin Van Dyke
                           636 Grand Avenue
                           Des Moines, Iowa 50309
                           Fax No.:  (515) 245-6000


         Notice so given shall, in the case of notice so given by certified
mail, be deemed to be given and received on the date of actual delivery, in the
case of notice so given by express delivery service, on the date of actual
delivery and, in the case of notice so given by facsimile transmission or
personal delivery, on the date of actual transmission or personal delivery, as
the case may be.

4. Severability.

         If any provision of this Agreement shall be held to be illegal, invalid
or unenforceable under any applicable law, then such contravention or invalidity
shall not invalidate the entire Agreement. Such provision shall be deemed to be
modified to the extent necessary to render it legal, valid and enforceable, and
if no such modification shall render it legal, valid and enforceable, then this
Agreement shall be construed as if not containing the provision held to be
invalid, and the rights and obligations of the parties shall be construed and
enforced accordingly.

5. Complete Agreement.

         This Agreement and those documents expressly referred to herein and of
even date herewith, embody the complete agreement and understanding among the
parties and supersede and preempt any prior understandings, agreements or
representations by or among the parties, written or oral, which may have related
to the subject matter hereof in any way.



                                       14
<PAGE>

6. Counterparts.

         This Agreement may be executed in any number of counterparts and by
different parties hereto in separate counterparts, with the same effect as if
all parties had signed the same document. All such counterparts shall be deemed
an original, shall be construed together and shall constitute one and the same
instrument.

7. Successors and Assigns.

         This Agreement is intended to bind and inure to the benefit of and be
enforceable by and against the Stockholder and the Company, and their respective
heirs, successors and assigns. Stockholder hereby agrees not to transfer or
assign, directly or indirectly, any of the Stock (other than through a market
sale) unless such transferee or assignee agrees in writing (i) to be bound by
the provisions of this Agreement and (ii) not to make subsequent assignments or
transfers other than in accordance with this Agreement. Notwithstanding the
foregoing, any holder of the Stock (other than a holder who purchases the Stock
through a market sale) shall be bound by the provisions of this Agreement even
if such holder is not a party hereto or otherwise agreed in writing to be bound
by the provisions hereof.

8. CHOICE OF LAW.

         THE INTERNAL LAW OF THE STATE OF TEXAS (AND NOT THE LAW OF CONFLICTS)
WILL GOVERN THE CONSTRUCTION, VALIDITY AND INTERPRETATION OF THIS AGREEMENT.

9. Remedies.

         Each of the parties to this Agreement will be entitled to enforce its
rights under this Agreement specifically, to recover damages by reason of any
breach of any provision of this Agreement and to exercise all other rights
existing in its favor. The parties hereto agree and acknowledge that money
damages may not be an adequate remedy for any breach of the provisions of this
Agreement and that any party may in its sole discretion apply to any court of
law or equity of competent jurisdiction for specific performance and/or
injunctive relief in order to enforce or prevent any violations of the
provisions of this Agreement. In the event a party hereto brings an action under
this agreement, the prevailing party in such dispute shall be entitled to
recover from the losing party all fees, costs and expenses of enforcing any
right of such prevailing party under or with respect to this Agreement,
including without limitation such reasonable fees and expenses of attorneys and
accountants, which shall include, without limitation, all fees, costs and
expenses of appeals.

10. Amendments and Waivers.

         Any provision of this Agreement may be amended or waived only with the
prior written consent of each of the parties hereto.



                                       15
<PAGE>

         IN WITNESS WHEREOF, the parties have executed this Agreement on the day
and year first above written.


                                                   AdvancePCS



                                                   By:
                                                      --------------------------
                                                   Name:
                                                        ------------------------
                                                   Title:
                                                         -----------------------



                                                   Wellmark, Inc.



                                                   By:
                                                      --------------------------
                                                   Name:
                                                        ------------------------
                                                   Title:
                                                         -----------------------



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