Document:

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                                                                     EXHIBIT 4.2

                               FORM OF GUARANTEE
                                      OF
                             WAL-MART STORES, INC.

     For value received, Wal-Mart Stores, Inc., a Delaware corporation, having
its principal executive offices at 702 S.W. 8th Street, Bentonville, Arkansas
72716 (the "Guarantor," which term includes any successor Person thereto under
the Indenture referred to in the Security upon which this Guarantee is
endorsed), hereby unconditionally and irrevocably guarantees to the Holder of
the Guaranteed Security upon which this Guarantee is endorsed and to the Trustee
on behalf of such Holder, the due and punctual payment of the principal of,
premium, if any, and interest on such Guaranteed Security, the due and punctual
payments of any Redemption Price or Repurchase Price referred to therein, the
due and punctual payment of any sinking fund or analogous payments referred to
therein, and the due and punctual payment of any other amounts due and payable
to the Holder of the Guaranteed Security pursuant to the terms of the Guaranteed
Security (the "Guaranteed Obligations"), when and as the same shall become due
and payable, whether on the Stated Maturity, by declaration of acceleration,
call for redemption or otherwise, according to the terms of the Guaranteed
Security and of the Indenture referred to therein (as amended and supplemented
from time to time, the "Indenture").  All terms used and not otherwise defined
in this Guarantee shall have the respective meanings ascribed to them in the
Indenture.

     If [insert here the name of the Applicable Issuer], a Cayman Islands
limited liability company (herein called the "Borrower," which term includes any
successor Person thereto under such Indenture), fails to pay punctually any
Guaranteed Obligation, the Guarantor hereby agrees to pay that Guaranteed
Obligation, or to cause that Guaranteed Obligation to be paid, punctually when
and as the same shall become due and payable, whether on the Stated Maturity or
any declaration of acceleration, call for redemption, exercise of any Repurchase
Right of the Holders or otherwise, and as if such payment were made by the
Borrower.

     The Guarantor hereby agrees that its obligations hereunder shall be as if
it were principal debtor and not merely a surety, and shall be absolute and
unconditional, irrespective of, and shall be unaffected by, any invalidity,
irregularity or unenforceability of such Guaranteed Security or the Indenture,
any failure to enforce the provisions of such Guaranteed Security or

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the Indenture, or any waiver, modification or indulgence granted to the Borrower
with respect thereto, by the Holder of such Guaranteed Security or the Trustee
or any other circumstance which may otherwise constitute a legal or equitable
discharge of a surety or guarantor; provided, however, that, notwithstanding the
foregoing, no such waiver, modification or indulgence shall, without the consent
of the Guarantor, increase the principal amount of such Guaranteed Security,
increase the interest rate thereon, change the method or methods by which the
interest rate thereon is determined or computed in a manner adverse to the
Guarantor, increase any premium payable upon prepayment, redemption or
repurchase thereof, alter the Stated Maturity thereof, increase the principal
amount of any Original Issue Discount Security that would be due and payable
upon a declaration of acceleration of the maturity thereof pursuant to Article
Five of the Indenture or increase the amount of any Redemption Price or any
Repurchase Price or change the method or methods by which any Redemption Price
or Repurchase Price is determined in a manner adverse to the Guarantor.

     The Guarantor hereby waives diligence, presentment, demand for payment,
filing of claims with a court in the event of merger or bankruptcy of the
Borrower, any right to require, or any requirement that the Guarantor first
institute and prosecute, a proceeding against the Borrower to collect any
Guaranteed Obligation, protest or notice with respect to such Guaranteed
Security or the indebtedness evidenced thereby or with respect to any sinking
fund or analogous payment required under such Security and all demands
whatsoever, and covenants that this Guarantee will not be discharged except by
payment in full of the principal of, premium, if any, and interest on such
Guaranteed Security.

     The Guarantor shall be subrogated to all rights of the Holder of such
Guaranteed Security and the Trustee against the Borrower in respect of any
amounts paid to such Holder by the Guarantor pursuant to the provisions of this
Guarantee; provided, however, that the Guarantor shall not be entitled to
enforce, or to receive any payments arising out of or based upon, that right of
subrogation until the principal of, premium, if any, and interest on all
Guaranteed Securities of the Series of which such Guaranteed Security is a part
issued under such Indenture shall have been paid in full.

     No reference herein to such Indenture and no provisions of this Guarantee
or of such Indenture shall alter or impair the guarantees of the Guarantor,
which are absolute and unconditional, of the due and punctual payment of the
principal of, premium, if any, and interest on, and any sinking fund or
analogous payments with respect to, the Guaranteed Security upon which this
Guarantee is endorsed.

     This Guarantee shall not be valid or create an obligation of the Guarantor
for any purpose until the certificate of authentication of such Guaranteed
Security shall have been manually executed by or on behalf of the Trustee under
such Indenture.

     All terms used in this Guarantee that are defined in such Indenture shall
have the meanings ascribed to them in such Indenture.

     This Guarantee shall be governed by and construed in accordance with the
laws of the State of New York.

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     Executed and dated as of the date of the Guaranteed Security on which this
Guarantee is endorsed.

                                   WAL-MART STORES, INC.

                                   By:_____________________________
                                   Name:
                                   Title:<PAGE>   1

                                                                     EXHIBIT 4.1

                                                                  EXECUTION COPY

                                                                            FORM
                                                                       EXHIBIT B
                                                                   TO SECURITIES
                                                                        PURCHASE
                                                                       AGREEMENT

      VOID AFTER 5:00 P.M., NEW YORK CITY
      TIME, ON JUNE 29, 2005
      (UNLESS EXTENDED PURSUANT TO SECTION 2 HEREOF)

      THIS WARRANT AND THE SHARES ISSUABLE UPON EXERCISE OF THIS WARRANT HAVE
      NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE
      "SECURITIES ACT"), OR THE SECURITIES LAWS OF ANY STATE OF THE UNITED
      STATES OR ANY OTHER JURISDICTION. THE SECURITIES REPRESENTED HEREBY MAY
      NOT BE OFFERED, SOLD OR TRANSFERRED IN THE ABSENCE OF AN EFFECTIVE
      REGISTRATION STATEMENT FOR THE SECURITIES UNDER APPLICABLE SECURITIES LAWS
      UNLESS OFFERED, SOLD OR TRANSFERRED PURSUANT TO AN AVAILABLE EXEMPTION
      FROM THE REGISTRATION REQUIREMENTS OF THOSE LAWS.

                                         Right to Purchase __________ Shares of
                                         Common Stock, par value $.001 per share

Date: June 29, 2001

                                     FORM OF
                                 VIROLOGIC, INC.
                             STOCK PURCHASE WARRANT

       [The Schedule of Warrantholders is attached hereto as Addendum A.]

       THIS CERTIFIES THAT, for value received, ______________________________,
or its registered assigns, is entitled to purchase from ViroLogic, Inc., a
corporation organized under the laws of the State of Delaware (the "COMPANY"),
at any time or from time to time during the period specified in Section 2
hereof, ______________________________________________________ (________) fully
paid and nonassessable shares of the Company's common stock, par value $.001 per
share (the "COMMON STOCK"), at an exercise price per share (the "EXERCISE
PRICE") equal to $2.805. The number of shares of Common Stock purchasable
hereunder (the "WARRANT SHARES") and the Exercise Price are subject to
adjustment as provided in Section 4 hereof. The term "WARRANTS" means this
Warrant and the other warrants of the Company issued pursuant to that certain
Securities Purchase Agreement, dated as of June 29, 2001, by and among the
Company and the other signatories thereto (the "SECURITIES PURCHASE AGREEMENT").

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       This Warrant is subject to the following terms, provisions and
conditions:

       1. Manner of Exercise; Issuance of Certificates; Payment for Shares.
Subject to the provisions hereof, including, without limitation, the limitations
contained in Section 7 hereof, this Warrant may be exercised by the holder
hereof, in whole or in part, by the surrender of this Warrant, together with a
completed exercise agreement in the form attached hereto (the "EXERCISE
AGREEMENT"), to the Company during normal business hours on any business day at
the Company's principal executive offices (or such other office or agency of the
Company as it may designate by notice to the holder hereof), and (i) payment to
the Company in cash, by certified or official bank check or by wire transfer for
the account of the Company, of the Exercise Price for the Warrant Shares
specified in the Exercise Agreement or (ii) if the holder is effectuating a
Cashless Exercise (as defined in Section 11(c) hereof) pursuant to Section 11(c)
hereof, delivery to the Company of a written notice of an election to effect a
Cashless Exercise for the Warrant Shares specified in the Exercise Agreement.
The Warrant Shares so purchased shall be deemed to be issued to the holder
hereof or such holder's designee, as the record owner of such shares, as of the
close of business on the date on which this Warrant shall have been surrendered,
the completed Exercise Agreement shall have been delivered, and payment shall
have been made for such shares as set forth above or, if such date is not a
business date, on the next succeeding business date. The Warrant Shares so
purchased, representing the aggregate number of shares specified in the Exercise
Agreement, shall (by the Company or through its transfer agent) be delivered
(i.e., deposited with a nationally-recognized overnight courier service postage
prepaid) to the holder hereof within a reasonable time, not exceeding two
business days, after this Warrant shall have been so exercised (the "DELIVERY
PERIOD"). If the Company's transfer agent is participating in the Depository
Trust Company ("DTC") Fast Automated Securities Transfer program, and so long as
the certificates therefor do not bear a legend (pursuant to the terms of the
Securities Purchase Agreement) and the holder is not obligated to return such
certificate for the placement of a legend thereon (pursuant to the terms of the
Securities Purchase Agreement), the Company shall cause its transfer agent to
electronically transmit the Warrant Shares so purchased to the holder by
crediting the account of the holder or its nominee with DTC through its Deposit
Withdrawal Agent Commission system ("DTC TRANSFER"). If the aforementioned
conditions to a DTC Transfer are not satisfied, the Company shall deliver as
provided herein to the holder physical certificates representing the Warrant
Shares so purchased. Further, the holder may instruct the Company to deliver to
the holder physical certificates representing the Warrant Shares so purchased in
lieu of delivering such shares by way of DTC Transfer. Any certificates so
delivered shall be in such denominations as may be reasonably requested by the
holder hereof, shall be registered in the name of such holder or such other name
as shall be designated by such holder and, following the date on which the
Warrant Shares have been registered under the Securities Act pursuant to that
certain Registration Rights Agreement, dated as of June 29, 2001, by and between
the Company and the other signatories thereto (the "REGISTRATION RIGHTS
AGREEMENT") or otherwise may be sold by the holder pursuant to Rule 144
promulgated under the Securities Act (or a successor rule), shall not bear any
restrictive legend. If this Warrant shall have been exercised only in part, then
the Company shall, at its expense, at the time of delivery of such certificates,
deliver to the holder a new Warrant representing the number of shares with
respect to which this Warrant shall not then have been exercised.

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       If, at any time, a holder of this Warrant submits this Warrant, an
Exercise Agreement and payment to the Company of the Exercise Price for each of
the Warrant Shares specified in the Exercise Agreement (including pursuant to a
Cashless Exercise), and the Company fails for any reason to deliver, on or prior
to the fourth business day following the expiration of the Delivery Period for
such exercise, the number of shares of Common Stock to which the holder is
entitled upon such exercise (an "EXERCISE DEFAULT"), then the Company shall pay
to the holder payments ("EXERCISE DEFAULT PAYMENTS") for an Exercise Default in
the amount of (a) (N/365), multiplied by (b) the amount by which the Market
Price (as defined in Section 4(l) hereof) on the date the Exercise Agreement
giving rise to the Exercise Default is transmitted in accordance with this
Section 1 (the "EXERCISE DEFAULT DATE") exceeds the Exercise Price in respect of
such Warrant Shares, multiplied by (c) the number of shares of Common Stock the
Company failed to so deliver in such Exercise Default, multiplied by (d) .18,
where N = the number of days from the Exercise Default Date to the date that the
Company effects the full exercise of this Warrant which gave rise to the
Exercise Default. The accrued Exercise Default Payment for each calendar month
shall be paid in cash or shall be convertible into Common Stock, at the holder's
option, as follows:

              (a) In the event holder elects to take such payment in cash, cash
payment shall be made to holder by the fifth day of the month following the
month in which it has accrued; and

              (b) In the event holder elects to take such payment in Common
Stock, the holder may convert such payment amount into Common Stock (in
accordance with the terms, conditions and limitations contained in Article IV of
the Certificate of Designations, Preferences and Rights (the "CERTIFICATE OF
DESIGNATION") governing the Company's Series A Convertible Preferred Stock (the
"SERIES A PREFERRED STOCK")) at the lower of the Exercise Price or the Market
Price (as defined in Section 4(l)) (as in effect at the time of conversion) at
any time after the fifth day of the month following the month in which it has
accrued.

       Nothing herein shall limit the holder's right to pursue actual damages
for the Company's failure to maintain a sufficient number of authorized shares
of Common Stock as required pursuant to the terms of Section 3(b) hereof or to
otherwise issue shares of Common Stock upon exercise of this Warrant in
accordance with the terms hereof, and the holder shall have the right to pursue
all remedies available at law or in equity (including a decree of specific
performance and/or injunctive relief).

       2. Period of Exercise. This Warrant is immediately exercisable, at any
time or from time to time on or after the date of initial issuance of this
Warrant (the "ISSUE DATE") and before 5:00 p.m., New York City time, on the
fourth anniversary of the Issue Date (the "EXERCISE PERIOD"). The Exercise
Period shall automatically be extended by one (1) day for each day on which the
Company does not have a number of shares of Common Stock reserved for issuance
upon exercise hereof at least equal to the number of shares of Common Stock
issuable upon exercise hereof.

       3. Certain Agreements of the Company. The Company hereby covenants and
agrees as follows:

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<PAGE>   4

              (a) Shares to be Fully Paid. All Warrant Shares will, upon
issuance in accordance with the terms of this Warrant, be validly issued, fully
paid, and nonassessable and free from all taxes, liens, claims and encumbrances.

              (b) Reservation of Shares. During the Exercise Period, the Company
shall at all times have authorized, and reserved for the purpose of issuance
upon exercise of this Warrant, a sufficient number of shares of Common Stock to
provide for the exercise in full of this Warrant (without giving effect to the
limitations on exercise set forth in Section 7(g) hereof).

              (c) Listing. The Company shall promptly secure the listing of the
shares of Common Stock issuable upon exercise of this Warrant upon each national
securities exchange or automated quotation system, if any, upon which shares of
Common Stock are then listed or become listed (subject to official notice of
issuance upon exercise of this Warrant) and shall maintain, so long as any other
shares of Common Stock shall be so listed, such listing of all shares of Common
Stock from time to time issuable upon the exercise of this Warrant; and the
Company shall so list on each national securities exchange or automated
quotation system, as the case may be, and shall maintain such listing of, any
other shares of capital stock of the Company issuable upon the exercise of this
Warrant if and so long as any shares of the same class shall be listed on such
national securities exchange or automated quotation system.

              (d) Certain Actions Prohibited. The Company will not, by amendment
of its charter or through any reorganization, transfer of assets, consolidation,
merger, dissolution, issue or sale of securities, or any other voluntary action,
avoid or seek to avoid the observance or performance of any of the terms to be
observed or performed by it hereunder, but will at all times in good faith
assist in the carrying out of all the provisions of this Warrant and in the
taking of all such action as may reasonably be requested by the holder of this
Warrant in order to protect the economic benefit inuring to the holder hereof
and the exercise privilege of the holder of this Warrant against dilution or
other impairment, consistent with the tenor and purpose of this Warrant. Without
limiting the generality of the foregoing, the Company (i) will not increase the
par value of any shares of Common Stock receivable upon the exercise of this
Warrant above the Exercise Price then in effect, and (ii) will take all such
actions as may be necessary or appropriate in order that the Company may validly
and legally issue fully paid and nonassessable shares of Common Stock upon the
exercise of this Warrant.

              (e) Successors and Assigns. This Warrant will be binding upon any
entity succeeding to the Company by merger, consolidation, or acquisition of all
or substantially all of the Company's assets.

              (f) Blue Sky Laws. The Company shall, on or before the date of
issuance of any Warrant Shares, take such actions as the Company shall
reasonably determine are necessary to qualify the Warrant Shares for, or obtain
exemption for the Warrant Shares for, sale to the holder of this Warrant upon
the exercise hereof under applicable securities or "blue sky" laws of the states
of the United States, and shall provide evidence of any such action so taken to
the holder of this Warrant prior to such date; provided, however, that the
Company shall not be required in connection therewith or as a condition thereto
to (a) qualify to do business in any jurisdiction where it would

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not otherwise be required to qualify but for this Section 3(f), (b) subject
itself to general taxation in any such jurisdiction or (c) file a general
consent to service of process in any such jurisdiction.

       4. Antidilution Provisions. During the Exercise Period, the Exercise
Price and the number of Warrant Shares issuable hereunder shall be subject to
adjustment from time to time as provided in this Section 4.

              In the event that any adjustment of the Exercise Price as required
herein results in a fraction of a cent, such Exercise Price shall be rounded up
or down to the nearest cent.

              (a) Adjustment of Exercise Price. Except as otherwise provided in
Sections 4(c) and 4(e) hereof, if and whenever prior to the second anniversary
of the Issue Date the Company issues or sells, or in accordance with Section
4(b) hereof is deemed to have issued or sold, any shares of Common Stock for no
consideration or for a consideration per share less than the Exercise Price on
the Measurement Date (as such terms are hereinafter defined) (a "DILUTIVE
ISSUANCE"), then effective immediately upon the Dilutive Issuance, the Exercise
Price will be adjusted to equal the per share amount of such shares of Common
Stock issued or sold, or deemed to have been issued of sold, in such Dilutive
Issuance.

Notwithstanding the foregoing, no adjustment shall be made pursuant to this
Section 4(a) if such adjustment would result in an increase in the Exercise
Price.

              (b) Effect on Exercise Price of Certain Events. For purposes of
determining the adjusted Exercise Price under Section 4(a) hereof, the following
will be applicable:

                     (i) Issuance of Rights or Options. If the Company in any
manner issues or grants any warrants, rights or options, whether or not
immediately exercisable, to subscribe for or to purchase Common Stock or other
securities exercisable, convertible into or exchangeable for Common Stock
("CONVERTIBLE SECURITIES") (such warrants, rights and options to purchase Common
Stock or Convertible Securities are hereinafter referred to as "OPTIONS") and
the price per share for which Common Stock is issuable upon the exercise of such
Options (and the price of any conversion of Convertible Securities, if
applicable) is less than the Exercise Price in effect on the Measurement Date of
such securities ("BELOW MARKET OPTIONS"), then the maximum total number of
shares of Common Stock issuable upon the exercise of all such Below Market
Options (assuming full exercise, conversion or exchange of Convertible
Securities, if applicable) will, as of the date of the issuance or grant of such
Below Market Options, be deemed to be outstanding and to have been issued and
sold by the Company for such price per share. For purposes of the preceding
sentence, the "price per share for which Common Stock is issuable upon the
exercise of such Below Market Options" is determined by dividing (i) the total
amount, if any, received or receivable by the Company as consideration for the
issuance or granting of all such Below Market Options, plus the minimum
aggregate amount of additional consideration, if any, payable to the Company
upon the exercise of all such Below Market Options, plus, in the case of
Convertible Securities issuable upon the exercise of such Below Market Options,
the minimum aggregate amount of additional consideration payable upon the
exercise, conversion or exchange thereof (determined in accordance with the
calculation method set forth in (b)(ii) below) at the time such Convertible
Securities first become exercisable, convertible or exchangeable, by (ii) the
maximum total number of shares of

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Common Stock issuable upon the exercise of all such Below Market Options
(assuming full conversion of Convertible Securities, if applicable). No further
adjustment to the Exercise Price will be made upon the actual issuance of such
Common Stock upon the exercise of such Below Market Options or upon the
exercise, conversion or exchange of Convertible Securities issuable upon
exercise of such Below Market Options. If, in any case, the total number of
shares of Common Stock issuable upon exercise of any Below Market Options or
upon exercise, conversion or exchange of any Convertible Securities is not, in
fact, issued and the rights to exercise such option or to exercise, convert or
exchange such Convertible Securities shall have expired or terminated, the
Exercise Price then in effect will be readjusted to the Exercise Price which
would have been in effect at the time of such expiration or termination had such
Below Market Options or Convertible Securities, to the extent outstanding
immediately prior to such expiration or termination (other than in respect of
the actual number of shares of Common Stock issued upon exercise or conversion
thereof), never been issued.

                     (ii) Issuance of Convertible Securities.

                            (A) If the Company in any manner issues or sells any
Convertible Securities, which Convertible Securities do not have a fluctuating
conversion or exercise price or exchange ratio, whether or not immediately
convertible (other than where the same are issuable upon the exercise of
Options) and the price per share for which Common Stock is issuable upon such
exercise, conversion or exchange (as determined pursuant to Section 4(b)(ii)(B)
if applicable) is less than the Exercise Price in effect on the Measurement
Date, then the maximum total number of shares of Common Stock issuable upon the
exercise, conversion or exchange of all such Convertible Securities will, as of
the date of the issuance of such Convertible Securities, be deemed to be
outstanding and to have been issued and sold by the Company for such price per
share. For the purposes of the preceding sentence, the "price per share for
which Common Stock is issuable upon such exercise, conversion or exchange" is
determined by dividing (i) the total amount, if any, received or receivable by
the Company as consideration for the issuance or sale of all such Convertible
Securities, plus the minimum aggregate amount of additional consideration, if
any, payable to the Company upon the exercise, conversion or exchange thereof at
the time such Convertible Securities first become exercisable, convertible or
exchangeable, by (ii) the maximum total number of shares of Common Stock
issuable upon the exercise, conversion or exchange of all such Convertible
Securities. No further adjustment to the Exercise Price will be made upon the
actual issuance of such Common Stock upon exercise, conversion or exchange of
such Convertible Securities.

                            (B) If the Company in any manner issues or sells any
Convertible Securities with a fluctuating conversion or exercise price or
exchange ratio (a "VARIABLE RATE CONVERTIBLE SECURITY"), then the "price per
share for which Common Stock is issuable upon such exercise, conversion or
exchange" for purposes of the calculation contemplated by Section 4(b)(ii)(A)
shall be deemed to be the lowest price per share which would be applicable
(assuming all holding period and other conditions to any discounts contained in
such Convertible Security have been satisfied) if the Exercise Price on the
Measurement Date of such Convertible Security was 75% of the Exercise Price on
such date (the "ASSUMED VARIABLE EXERCISE PRICE"). Further, if the Exercise
Price at any time or times thereafter is less then or equal to the Assumed
Variable Exercise

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Price last used for making any adjustment under this Section 4 with respect to
any Variable Rate Convertible Security, the Exercise Price in effect at such
time shall be readjusted to equal the Exercise Price which would have resulted
if the Assumed Variable Exercise Price at the time of issuance of the Variable
Rate Convertible Security had been 75% of the Exercise Price existing at the
time of the adjustment required by this sentence.

                     (iii) Change in Option Price or Conversion Rate. If there
is a change at any time in (i) the amount of additional consideration payable to
the Company upon the exercise of any Options; (ii) the amount of additional
consideration, if any, payable to the Company upon the exercise, conversion or
exchange of any Convertible Securities; or (iii) the rate at which any
Convertible Securities are convertible into or exchangeable for Common Stock (in
each such case, other than under or by reason of provisions designed to protect
against dilution and except when an adjustment is made pursuant to (ii)(B)
above), the Exercise Price in effect at the time of such change will be
readjusted to the Exercise Price which would have been in effect at such time
had such Options or Convertible Securities still outstanding provided for such
changed additional consideration or changed conversion rate, as the case may be,
at the time initially granted, issued or sold.

                     (iv) Calculation of Consideration Received. If any Common
Stock, Options or Convertible Securities are issued, granted or sold for cash,
the consideration received therefor for purposes of this Warrant will be the
amount received by the Company therefor, after deduction of all commissions,
underwriting discounts or allowances and other expenses paid or incurred by the
Company in connection with such issuance, grant or sale. In case any Common
Stock, Options or Convertible Securities are issued or sold for a consideration
part or all of which shall be other than cash, including in the case of a
strategic or similar arrangement in which the other entity will provide services
to the Company, purchase services from the Company or otherwise provide
intangible consideration to the Company, the amount of the consideration other
than cash received by the Company (including the net present value of the
consideration expected by the Company for the provided or purchased services)
will be the fair market value of such consideration, except where such
consideration consists of securities, in which case the amount of consideration
received by the Company will be the Market Price thereof as of the date of
receipt. In case any Common Stock, Options or Convertible Securities are issued
in connection with any merger or consolidation in which the Company is the
surviving corporation, the amount of consideration therefor will be deemed to be
the fair market value of such portion of the net assets and business of the
non-surviving corporation as is attributable to such Common Stock, Options or
Convertible Securities, as the case may be. Notwithstanding anything else herein
to the contrary, if Common Stock, Options or Convertible Securities are issued,
granted or sold in conjunction with each other as part of a single transaction
or in a series of related transactions, the holder of this Warrant may elect to
determine the amount of consideration deemed to be received by the Company
therefore by deducting the fair value of any type of securities (the
"DISREGARDED SECURITIES") issued, granted or sold in such transaction or series
of transactions. If the holder makes an election pursuant to the immediately
preceding sentence, no adjustment to the Exercise Price shall be made pursuant
to this Section 4 for the issuance of the Disregarded Securities or upon any
conversion or exercise thereof. For example, if the Company were to issue
convertible notes having a face value of $1,000,000 and warrants to purchase
shares of Common Stock at an exercise price equal to the market price of the

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Common Stock on the date of issuance of such warrants in exchange for $1,000,000
of consideration, the fair value of the warrants would be subtracted from the
$1,000,000 of consideration received by the Company for the purposes of
determining whether the shares of Common Stock issuable upon conversion of the
convertible notes shall be deemed to be issued at a price per share below market
price and, if so, for purposes of determining any adjustment to the Exercise
Price hereunder as a result of the issuance of the Convertible Securities. The
Company shall calculate, using standard commercial valuation methods appropriate
for valuing such assets, the fair market value of any consideration other than
cash or securities; provided, however, that if the holder hereof does not agree
to such fair market value calculation within three business days after receipt
thereof from the Company, then such fair market value will be determined in good
faith by an investment banker or other appropriate expert of national reputation
selected by the Company and reasonably acceptable to the holder hereof, with the
costs of such appraisal to be borne by the Company.

                     (v) Issuances Pursuant to Existing Securities. If the
Company, at any time during the Exercise Period, issues (or becomes obligated to
issue) shares of Common Stock pursuant to any antidilution or similar
adjustments contained in a security or instrument outstanding as of the date
hereof but not included on Schedule 3(d) of the Securities Purchase Agreement,
then all shares of Common Stock so issued shall be deemed to have been issued
for no consideration. If the Company, at any time during the Exercise Period,
issues (or becomes obligated to issue) shares of Common Stock pursuant to any
antidilution or similar adjustments contained in a security or instrument
included on Schedule 3(d) of the Securities Purchase Agreement as a result of
the issuance of the Preferred Shares or Warrants and the number of shares that
the Company issues (or is obligated to issue) as a result of such initial
issuance exceeds the amount specified on Schedule 3(d) of the Securities
Purchase Agreement, such excess shares shall be deemed to have been issued for
no consideration.

                     (vi) Exceptions to Adjustment of Exercise Price. No
adjustment to the Exercise Price will be made (i) except as otherwise provided
in Section 4(b)(v), upon the exercise of any warrants, options or convertible
securities issued and outstanding on the Issue Date that are set forth on
Schedule 3(d) of the Securities Purchase Agreement in accordance with the terms
of such securities as of such date; (ii) upon the grant or exercise of any stock
or options which may hereafter be granted to or exercised by any employee,
director or consultant under any employee benefit plan of the Company now
existing or to be implemented in the future, so long as the issuance of such
stock or options is approved by a majority of the Board of Directors of the
Company or a majority of the members of a committee of non-employee directors
established for such purpose; (iii) upon the issuance of any shares of Series A
Preferred Stock or Warrants issued or issuable in accordance with the terms of
the Securities Purchase Agreement; (iv) upon conversion of the Series A
Preferred Stock or exercise of the Warrants, (v) the issuance of securities in
connection with strategic business partnerships or joint ventures (including,
without limitation, such transactions with major pharmaceutical lab or life
sciences companies), the primary purpose of which, in the reasonable judgment of
the Board of Directors, is not to raise additional capital, or (vii) the
issuance of securities pursuant to any equipment financing from a bank or
similar financial or lending institution approved by the Board of Directors.

                                       8
<PAGE>   9

              (c) Subdivision or Combination of Common Stock. If the Company, at
any time during the Exercise Period, subdivides (by any stock split, stock
dividend, recapitalization, reorganization, reclassification or otherwise) its
shares of Common Stock into a greater number of shares, then, after the date of
record for effecting such subdivision, the Exercise Price in effect immediately
prior to such subdivision will be proportionately reduced. If the Company, at
any time during the Exercise Period, combines (by reverse stock split,
recapitalization, reorganization, reclassification or otherwise) its shares of
Common Stock into a smaller number of shares, then, after the date of record for
effecting such combination, the Exercise Price in effect immediately prior to
such combination will be proportionately increased.

              (d) Adjustment in Number of Shares. Upon each adjustment of the
Exercise Price pursuant to the provisions of this Section 4, the number of
shares of Common Stock issuable upon exercise of this Warrant at each such
Exercise Price shall be adjusted by multiplying a number equal to the Exercise
Price in effect immediately prior to such adjustment by the number of shares of
Common Stock issuable upon exercise of this Warrant at such Exercise Price
immediately prior to such adjustment and dividing the product so obtained by the
adjusted Exercise Price.

              (e) Consolidation, Merger or Sale. In case of any consolidation of
the Company with, or merger of the Company into, any other corporation, or in
case of any sale or conveyance of all or substantially all of the assets of the
Company other than in connection with a plan of complete liquidation of the
Company at any time during the Exercise Period, then as a condition of such
consolidation, merger or sale or conveyance, adequate provision will be made
whereby the holder hereof will have the right to acquire and receive upon
exercise of this Warrant in lieu of the shares of Common Stock immediately
theretofore acquirable upon the exercise of this Warrant, such shares of stock,
securities, cash or assets as may be issued or payable with respect to or in
exchange for the number of shares of Common Stock immediately theretofore
acquirable and receivable upon exercise of this Warrant had such consolidation,
merger or sale or conveyance not taken place. In any such case, the Company will
make appropriate provision to insure that the provisions of this Section 4
hereof will thereafter be applicable as nearly as may be in relation to any
shares of stock or securities thereafter deliverable upon the exercise of this
Warrant. The Company will not effect any consolidation, merger or sale or
conveyance unless prior to the consummation thereof, the successor corporation
(if other than the Company) assumes by written instrument the obligations under
this Warrant and the obligations to deliver to the holder hereof such shares of
stock, securities or assets as, in accordance with the foregoing provisions, the
holder may be entitled to acquire. Notwithstanding the foregoing, in the event
of any consolidation of the Company with, or merger of the Company into, any
other corporation, or the sale or conveyance of all or substantially all of the
assets of the Company, at any time during the Exercise Period, the holder hereof
shall, at its option, have the right to receive, in connection with such
transaction, cash consideration equal to the fair market value of this Warrant
as determined in accordance with customary valuation methodology used in the
investment banking industry.

              (f) Distribution of Assets. In case the Company shall declare or
make any distribution of its assets (or rights to acquire its assets) to holders
of Common Stock as a partial liquidating dividend, stock repurchase by way of
return of capital or otherwise (including any dividend or distribution to the
Company's stockholders of cash or shares (or rights to acquire shares)

                                       9
<PAGE>   10

of capital stock of a subsidiary) (a "DISTRIBUTION"), at any time during the
Exercise Period, then the holder hereof shall be entitled upon exercise of this
Warrant for the purchase of any or all of the shares of Common Stock subject
hereto, to receive the amount of such assets (or rights) which would have been
payable to the holder had such holder been the holder of such shares of Common
Stock on the record date for the determination of stockholders entitled to such
Distribution. If the Company distributes rights, warrants, options or any other
form of convertible securities and the right to exercise or convert such
securities would expire in accordance with their terms prior to the expiration
of the Exercise Period, then the terms of such securities shall provide that
such exercise or convertibility right shall remain in effect until 30 days after
the date the holder hereof receives such securities pursuant to the exercise
hereof.

              (g) Notice of Adjustment. Upon the occurrence of any event which
requires any adjustment of the Exercise Price, then, and in each such case, the
Company shall give notice thereof to the holder hereof, which notice shall state
the Exercise Price resulting from such adjustment and the increase or decrease
in the number of Warrant Shares purchasable at such price upon exercise, setting
forth in reasonable detail the method of calculation and the facts upon which
such calculation is based. Such calculation shall be certified by the chief
financial officer of the Company.

              (h) Minimum Adjustment of Exercise Price. No adjustment of the
Exercise Price shall be made in an amount of less than $.01, but any such lesser
adjustment shall be carried forward and shall be made at the time and together
with the next subsequent adjustment which, together with any adjustments so
carried forward, shall amount to not less than $.01.

              (i) No Fractional Shares. No fractional shares of Common Stock are
to be issued upon the exercise of this Warrant, but the Company shall pay a cash
adjustment in respect of any fractional share which would otherwise be issuable
in an amount equal to the same fraction of the Market Price of a share of Common
Stock on the date of such exercise.

              (j) Other Notices. In case at any time:

                     (i) the Company shall declare any dividend upon the Common
Stock payable in shares of stock of any class or make any other distribution
(other than dividends or distributions payable in cash out of retained earnings
consistent with the Company's past practices with respect to declaring dividends
and making distributions) to the holders of the Common Stock;

                     (ii) the Company shall offer for subscription pro rata to
the holders of the Common Stock any additional shares of stock of any class or
other rights;

                     (iii) there shall be any capital reorganization of the
Company, or reclassification of the Common Stock, or consolidation or merger of
the Company with or into, or sale of all or substantially all of its assets to,
another corporation or entity; or

                     (iv) there shall be a voluntary or involuntary dissolution,
liquidation or winding-up of the Company;

                                       10
<PAGE>   11

then, in each such case, the Company shall give to the holder of this Warrant
(a) notice of the date or estimated date on which the books of the Company shall
close or a record shall be taken for determining the holders of Common Stock
entitled to receive any such dividend, distribution, or subscription rights or
for determining the holders of Common Stock entitled to vote in respect of any
such reorganization, reclassification, consolidation, merger, sale, dissolution,
liquidation or winding-up and (b) in the case of any such reorganization,
reclassification, consolidation, merger, sale, dissolution, liquidation or
winding-up, notice of the date (or, if not then known, a reasonable estimate
thereof by the Company) when the same shall take place. Such notice shall also
specify the date on which the holders of Common Stock shall be entitled to
receive such dividend, distribution, or subscription rights or to exchange their
Common Stock for stock or other securities or property deliverable upon such
reorganization, reclassification, consolidation, merger, sale, dissolution,
liquidation, or winding-up, as the case may be. Such notice shall be given at
least fifteen (15) days prior to the record date or the date on which the
Company's books are closed in respect thereto. Failure to give any such notice
or any defect therein shall not affect the validity of the proceedings referred
to in clauses (i), (ii), (iii) and (iv) above. Notwithstanding the foregoing,
the Company shall publicly disclose the substance of any notice delivered
hereunder prior to delivery of such notice to the holder hereof.

              (k) Certain Events. If, at any time during the Exercise Period,
any event occurs of the type contemplated by the adjustment provisions of this
Section 4 but not expressly provided for by such provisions, the Company will
give notice of such event as provided in Section 4(g) hereof, and an appropriate
adjustment in the Exercise Price and the number of shares of Common Stock
acquirable upon exercise of this Warrant at each such Exercise Price shall be
made so that the rights of the holder shall be neither enhanced nor diminished
by such event.

              (l) Certain Definitions.

                     (i) "MARKET PRICE," as of any date, (i) means the average
of the closing sales prices for the shares of Common Stock on the Nasdaq
National Market or other trading market where such security is listed or traded
as reported by Bloomberg Financial Markets (or a comparable reporting service of
national reputation selected by the Company and reasonably acceptable to the
holders if Bloomberg Financial Markets is not then reporting sales prices of
such security)(collectively, "BLOOMBERG") for the ten (10) consecutive trading
days immediately preceding such date, or (ii) if the Nasdaq National Market is
not the principal trading market for the shares of Common Stock, the average of
the reported sales prices reported by Bloomberg on the principal trading market
for the Common Stock during the same period, or, if there is no sales price for
such period, the last sales price reported by Bloomberg for such period, or
(iii) if the foregoing do not apply, the last sales price of such security in
the over-the-counter market on the pink sheets or bulletin board for such
security as reported by Bloomberg, or if no sales price is so reported for such
security, the last bid price of such security as reported by Bloomberg, or (iv)
if market value cannot be calculated as of such date on any of the foregoing
bases, the Market Price shall be the average fair market value as reasonably
determined by an investment banking firm selected by the Company and reasonably
acceptable to the holder, with the costs of the appraisal to be borne by the
Company. The manner of determining the Market Price of the Common Stock set
forth in the foregoing definition

                                       11
<PAGE>   12

shall apply with respect to any other security in respect of which a
determination as to market value must be made hereunder.

                     (ii) "COMMON STOCK," for purposes of this Section 4,
includes the Common Stock and any additional class of stock of the Company
having no preference as to dividends or distributions on liquidation, provided
that the shares purchasable pursuant to this Warrant shall include only Common
Stock in respect of which this Warrant is exercisable, or shares resulting from
any subdivision or combination of such Common Stock, or in the case of any
reorganization, reclassification, consolidation, merger, or sale of the
character referred to in Section 4(e) hereof, the stock or other securities or
property provided for in such Section.

                     (iii) "MEASUREMENT DATE" means (i) for purposes of any
private offering of securities under Section 4(2) of the Securities Act of 1933,
as amended, the date that the Company enters into legally binding definitive
agreements for the issuance and sale of such securities and (ii) for purposes of
any other issuance of securities, the date of issuance thereof.

       5. Issue Tax. The issuance of certificates for Warrant Shares upon the
exercise of this Warrant shall be made without charge to the holder of this
Warrant or such shares for any issuance tax or other costs in respect thereof,
provided that the Company shall not be required to pay any tax which may be
payable in respect of any transfer involved in the issuance and delivery of any
certificate in a name other than the holder of this Warrant.

       6. No Rights or Liabilities as a Stockholder. This Warrant shall not
entitle the holder hereof to any voting rights or other rights as a stockholder
of the Company. No provision of this Warrant, in the absence of affirmative
action by the holder hereof to purchase Warrant Shares, and no mere enumeration
herein of the rights or privileges of the holder hereof, shall give rise to any
liability of such holder for the Exercise Price or as a stockholder of the
Company, whether such liability is asserted by the Company or by creditors of
the Company.

       7. Transfer, Exchange and Replacement of Warrant.

              (a) Restriction on Transfer. This Warrant and the rights granted
to the holder hereof are transferable, in whole or in part, upon surrender of
this Warrant, together with a properly executed assignment in the form attached
hereto, at the office or agency of the Company referred to in Section 7(e)
below, provided, however, that any transfer or assignment shall be subject to
the conditions set forth in Sections 7(f) and (g) hereof and to the provisions
of Sections 2(f) and 2(g) of the Securities Purchase Agreement. Each transferee
of this Warrant or any portion thereof shall be bound by the selling
restrictions set forth in Section 4(q) of the Securities Purchase Agreement,
which Section is incorporated herein by reference. Until due presentment for
registration of transfer on the books of the Company, the Company may treat the
registered holder hereof as the owner and holder hereof for all purposes, and
the Company shall not be affected by any notice to the contrary. Notwithstanding
anything to the contrary contained herein, the registration rights described in
Section 8 hereof are assignable only in accordance with the provisions of the
Registration Rights Agreement.

                                       12
<PAGE>   13

              (b) Warrant Exchangeable for Different Denominations. This Warrant
is exchangeable, upon the surrender hereof by the holder hereof at the office or
agency of the Company referred to in Section 7(e) below, for new Warrants of
like tenor of different denominations representing in the aggregate the right to
purchase the number of shares of Common Stock which may be purchased hereunder,
each of such new Warrants to represent the right to purchase such number of
shares (at the Exercise Price therefor) as shall be designated by the holder
hereof at the time of such surrender.

              (c) Replacement of Warrant. Upon receipt of evidence reasonably
satisfactory to the Company of the loss, theft, destruction, or mutilation of
this Warrant and, in the case of any such loss, theft, or destruction, upon
delivery of an indemnity agreement reasonably satisfactory in form and amount to
the Company, or, in the case of any such mutilation, upon surrender and
cancellation of this Warrant, the Company, at its expense, will execute and
deliver, in lieu thereof, a new Warrant of like tenor.

              (d) Cancellation; Payment of Expenses. Upon the surrender of this
Warrant in connection with any transfer, exchange, or replacement as provided in
this Section 7, this Warrant shall be promptly canceled by the Company. The
Company shall pay all taxes (other than securities transfer taxes) and all other
expenses (other than legal expenses, if any, incurred by the Holder or
transferees) and charges payable in connection with the preparation, execution,
and delivery of Warrants pursuant to this Section 7.

              (e) Warrant Register. The Company shall maintain, at its principal
executive offices (or such other office or agency of the Company as it may
designate by notice to the holder hereof), a register for this Warrant, in which
the Company shall record the name and address of the person in whose name this
Warrant has been issued, as well as the name and address of each transferee and
each prior owner of this Warrant.

              (f) Exercise or Transfer Without Registration. If, at the time of
the surrender of this Warrant in connection with any exercise, transfer, or
exchange of this Warrant, this Warrant (or, in the case of any exercise, the
Warrant Shares issuable hereunder), shall not be registered under the Securities
Act and under applicable state securities or blue sky laws, the Company may
require, as a condition of allowing such exercise, transfer, or exchange, (i)
that the holder or transferee of this Warrant, as the case may be, furnish to
the Company a written opinion of counsel (which opinion shall be in form,
substance and scope customary for opinions of counsel in comparable
transactions) to the effect that such exercise, transfer, or exchange may be
made without registration under the Securities Act and under applicable state
securities or blue sky laws (the cost of which shall be borne by the Company if
the Company's counsel renders such an opinion and up to $500 of such cost shall
be borne by the Company if the holder's counsel is requested to render such
opinion), (ii) that the holder or transferee execute and deliver to the Company
an investment letter in form and substance acceptable to the Company and (iii)
that the transferee be an "ACCREDITED INVESTOR" as defined in Rule 501(a)
promulgated under the Securities Act; provided that no such opinion, letter, or
status as an "accredited investor" shall be required in connection with a
transfer pursuant to Rule 144 under the Securities Act.

                                       13
<PAGE>   14

              (g) Additional Restrictions on Exercise or Transfer. In no event
shall the holder hereof have the right to exercise any portion of this Warrant
for shares of Common Stock or to dispose of any portion of this Warrant to the
extent that such right to effect such exercise or disposition would result in
the holder or any of its affiliates beneficially owning more than 4.99% of the
outstanding shares of Common Stock. For purposes of this Section 7(g),
beneficial ownership shall be determined in accordance with Section 13(d) of the
Securities Exchange Act of 1934, as amended, and Regulation 13D-G thereunder.
The restriction contained in this Section 7(g) may not be altered, amended,
deleted or changed in any manner whatsoever unless the holders of a majority of
the outstanding shares of Common Stock and the holder hereof shall approve, in
writing, such alteration, amendment, deletion or change. In addition, in no
event will the Company issue a number of shares of Common Stock upon exercise of
this Warrant in excess of such holder's pro rata Cap Amount (as defined in the
Certificate of Designation). In the event the Company is prohibited from issuing
such shares upon exercise of this Warrant due to the Cap Amount, the holder
shall have the remedies set forth in the Certificate of Designation with respect
to the shares that cannot be issued.

       8. Registration Rights. The initial holder of this Warrant (and certain
assignees thereof) is entitled to the benefit of such registration rights in
respect of the Warrant Shares as are set forth in the Registration Rights
Agreement, including the right to assign such rights to certain assignees, as
set forth therein.

       9. Notices. Any notices required or permitted to be given under the terms
of this Warrant shall be sent by certified or registered mail (return receipt
requested) or delivered personally or by courier or by confirmed telecopy, and
shall be effective five days after being placed in the mail, if mailed, or upon
receipt or refusal of receipt, if delivered personally or by courier, or by
confirmed telecopy, in each case addressed to a party. The addresses for such
communications shall be:

              If to the Company:

              ViroLogic, Inc.
              270 East Grand Avenue
              South San Francisco, California 94080
              Telephone: (650) 635-1100
              Attn: Chief Executive Officer

              with a copy simultaneously transmitted by like means to:

              Cooley Godward LLP
              4365 Executive Drive, Suite 1100
              San Diego, California 92121
              Telephone:  (858) 550-6000
              Attn: Christopher J. Kearns, Esq.

If to the holder, at such address as such holder shall have provided in writing
to the Company, or at such other address as such holder furnishes by notice
given in accordance with this Section 9.

                                       14
<PAGE>   15

       10. Governing Law; Jurisdiction. This Warrant shall be governed by and
construed in accordance with the laws of the State of Delaware. The Company
irrevocably consents to the jurisdiction of the United States federal courts and
state courts located in the State of Delaware in any suit or proceeding based on
or arising under this Warrant and irrevocably agrees that all claims in respect
of such suit or proceeding may be determined in such courts. The Company
irrevocably waives any objection to the laying of venue and the defense of an
inconvenient forum to the maintenance of such suit or proceeding. The Company
further agrees that service of process upon the Company mailed by certified or
registered mail shall be deemed in every respect effective service of process
upon the Company in any such suit or proceeding. Nothing herein shall affect the
holder's right to serve process in any other manner permitted by law. The
Company agrees that a final non-appealable judgment in any such suit or
proceeding shall be conclusive and may be enforced in other jurisdictions by
suit on such judgment or in any other lawful manner.

       11. Miscellaneous.

              (a) Amendments. Except as provided in Section 7(g) hereof, this
Warrant and any provision hereof may only be amended by an instrument in writing
signed by the Company and the holder hereof.

              (b) Descriptive Headings. The descriptive headings of the several
Sections of this Warrant are inserted for purposes of reference only, and shall
not affect the meaning or construction of any of the provisions hereof.

              (c) Cashless Exercise. This Warrant may be exercised at any time
after the first anniversary of the Issue Date and before the expiration of the
Exercise Period by presentation and surrender of this Warrant to the Company at
its principal executive offices with a written notice of the holder's intention
to effect a cashless exercise, including a calculation of the number of shares
of Common Stock to be issued upon such exercise in accordance with the terms
hereof (a "CASHLESS EXERCISE"). In the event of a Cashless Exercise, in lieu of
paying the Exercise Price in cash, the holder shall surrender this Warrant for
that number of shares of Common Stock determined by multiplying the number of
Warrant Shares to which it would otherwise be entitled by a fraction, the
numerator of which shall be the difference between the then current Market Price
of a share of the Common Stock on the date of exercise and the Exercise Price,
and the denominator of which shall be the then current Market Price per share of
Common Stock.

              (d) Trading Day. For purposes of this Warrant, the term "trading
day" means any day on which the principal United States securities exchange or
trading market where the Common Stock is then listed is open for trading.

              (e) Redemption of Warrant by Company.

                     (i) Provided that (x) all shares of Common Stock issuable
upon exercise of the Warrants are then (A) authorized and reserved for issuance,
(B) registered under the Securities Act of 1933, as amended, for resale by the
holders of the Warrants, (C) eligible to be traded on the Nasdaq National Market
or its successor, (y) all of the Required Conditions (as defined in the
Certificate of Designation) are satisfied, and (z) the Closing Bid Price (as
defined in the Certificate

                                       15
<PAGE>   16

of Designation) of the Common Stock is greater than 200% of the Exercise Price
as in effect on the Issue Date for twenty (20) or more consecutive trading days
immediately prior to the delivery by the Company of a Redemption Notice (as
defined below), the Company may elect, upon delivery of at least twenty (20)
days' prior written notice (the "REDEMPTION NOTICE") to the holder hereof, to
redeem all or a portion of the Warrants for a redemption amount equal to the
number of Warrant Shares issuable upon the exercise of all or a portion of this
Warrant that is being redeemed multiplied by $.10 (the "REDEMPTION AMOUNT"). For
example, if the Company elects to redeem Warrants exercisable for 10,000 shares
of Common Stock, the Company will pay the holder a Redemption Amount equal to
$1,000. In the event the Company elects to redeem only some of the outstanding
Warrants pursuant to this Section 11(e), such Warrants shall be redeemed pro
rata among all the holders of the Warrants based upon the percentage of Warrants
held by such holders against the total outstanding Warrants. Notwithstanding the
foregoing, the Company may only redeem Warrants exercisable for no more than
400,000 shares of Common Stock in any 30 day period.

                     (ii) The Company may not deliver a Notice of Redemption
unless on or prior to the date of delivery of a Notice of Redemption, the
Company shall have segregated on the books and records of the Company an amount
of cash sufficient to pay all amounts to which holders of the Warrants that are
being redeemed are entitled pursuant to Section 11(e)(i). Any Notice of
Redemption delivered shall be irrevocable and shall be accompanied by a
statement executed by a duly authorized officer of the Company.

                     (iii) The Redemption Amount shall be paid to the holder
within three (3) business days of the date of redemption set forth in the Notice
of Redemption; provided, however, that the Company shall not be obligated to
deliver any portion of the Redemption Amount until either this Warrant is
delivered to the Company or the holder notifies the Company that the Warrant has
been lost, stolen or destroyed and delivers the documentation in accordance with
Section 7(c) hereof. In the event only a portion of this Warrant is being
redeemed, the Company shall issue , at its expense, a new Warrant representing
the number of shares with respect to which this Warrant shall not then have been
redeemed or exercised.

                     (iv) Notwithstanding the delivery of a Redemption Notice,
the holder may exercise all or a portion of this Warrant subject to such
Redemption Notice by the delivery prior to the date of redemption set forth in
such notice of an Exercise Agreement pursuant to the procedures set forth in
Section 1.

              (f) Indemnification by Company.

                     (i) The Company shall hold harmless and indemnify the
holder of this Warrant from and against, and shall compensate and reimburse such
holder for, any damages which are directly or indirectly suffered or incurred by
such holder or to which such holder may otherwise become subject (regardless of
whether or not such damages relate to any third-party claim) and which arise
from or as a result of, or are directly or indirectly connected with any breach
of any of the Company's covenants set forth herein.

                                       16
<PAGE>   17

                     (ii) In the event of the assertion or commencement by any
person of any claim or legal proceeding with respect to which the holder may
have indemnification rights pursuant to this Section 11(f)(i), the holder shall
promptly notify the Company thereof in writing, but the failure to so notify the
Company will not limit the holder's rights to indemnification hereunder, except
to the extent the Company demonstrates that the defense of such action is
prejudiced by the failure to so give such notice.

                                       17
<PAGE>   18

       IN WITNESS WHEREOF, the Company has caused this Warrant to be signed by
its duly authorized officer.

                                        VIROLOGIC, INC.

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

                                       18
<PAGE>   19

                                   ADDENDUM A
                           SCHEDULE OF WARRANTHOLDERS

<TABLE>
<CAPTION>
                                              NUMBER OF SHARES OF
               NAME                       COMMON STOCK PURCHASEABLE
-------------------------------------------------------------------------
<S>                                       <C>
S.A.C. Capital Associates, LLC                       280,393

SDS Merchant Fund, L.P.                              119,608

Narrangansett I, L.P.                                131,373

Narragansett Offshore, Ltd.                          268,628

Castle Creek Healthcare Partners, L.P.                60,785

CCL Fund LLC                                          60,785

Crestwood Capital Partners, L.P.                     176,471

Crestwood Capital International, L.P.                100,000

Crestwood Capital Partners II, L.P.                   19,608

Bridgewood Capital Partners, L.P.                     25,491

Anvers Healthcare Investors, L.P.                     41,177

Anvers II, L.P.                                        7,894

Anvers L.P.                                           11,765
</TABLE>

                                       1.

<PAGE>   20

                           FORM OF EXERCISE AGREEMENT

         (TO BE EXECUTED BY THE HOLDER IN ORDER TO EXERCISE THE WARRANT)

To:    ViroLogic,Inc.
       270 East Grand Avenue
       South San Francisco, California 94080
       Telephone:  (650) 635-1100
       Attn:  Chief Executive Officer

       The undersigned hereby irrevocably exercises the right to purchase
_____________ shares of the Common Stock of ViroLogic, Inc., a corporation
organized under the laws of the State of Delaware (the "COMPANY"), evidenced by
the attached Warrant, and herewith [makes payment of the Exercise Price with
respect to such shares in full][elects to effect a Cashless Exercise (as defined
in Section 11(c) of such Warrant], all in accordance with the conditions and
provisions of said Warrant.

       The undersigned agrees not to offer, sell, transfer or otherwise dispose
of any Common Stock obtained on exercise of the Warrant, except under
circumstances that will not result in a violation of the Securities Act of 1933,
as amended, or any state securities laws. The undersigned represents that it is
an "accredited investor" as that term is defined in Rule 501(a) of Regulation D
under the Securities Act of 1933, as amended.

[ ]    The undersigned requests that the Company cause its transfer agent to
       electronically transmit the Common Stock issuable pursuant to this
       Exercise Agreement to the account of the undersigned or its nominee
       (which is _________________) with DTC through its Deposit Withdrawal
       Agent Commission System ("DTC TRANSFER"), provided that such transfer
       agent participates in the DTC Fast Automated Securities Transfer program.

[ ]    In lieu of receiving the shares of Common Stock issuable pursuant to this
       Exercise Agreement by way of DTC Transfer, the undersigned hereby
       requests that the Company cause its transfer agent to issue and deliver
       to the undersigned physical certificates representing such shares of
       Common Stock.

       The undersigned requests that a Warrant representing any unexercised
portion hereof be issued, pursuant to the Warrant, in the name of the Holder and
delivered to the undersigned at the address set forth below:

Dated:
      -----------------             ----------------------------------------
                                             Signature of Holder

                                    ----------------------------------------
                                             Name of Holder (Print)

                                             Address:

                                    ----------------------------------------

                                    ----------------------------------------

                                    ----------------------------------------

<PAGE>   21

                               FORM OF ASSIGNMENT

       FOR VALUE RECEIVED, the undersigned hereby sells, assigns, and transfers
all the rights of the undersigned under the within Warrant, with respect to the
number of shares of Common Stock covered thereby set forth hereinbelow, to:

<TABLE>
<CAPTION>
Name of Assignee              Address                             No. of Shares
----------------              -------                             -------------
<S>                           <C>                                 <C>
</TABLE>

, and hereby irrevocably constitutes and appoints
_____________________________________ as agent and attorney-in-fact to transfer
said Warrant on the books of the within-named corporation, with full power of
substitution in the premises.

Dated: _____________________, ____

In the presence of

------------------

                                Name:
                                     -----------------------------------

                                     Signature: ________________________________
                                     Title of Signing Officer or Agent (if any):

                                                --------------------------------
                                     Address:
                                                --------------------------------

                                                --------------------------------

                                     Note:   The above signature should
                                             correspond exactly with the name on
                                             the face of the within Warrant.

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