<PAGE>

                                                                   EXHIBIT 10.26


     The security represented by this certificate was originally issued
     on December 16, 1997, and has not been registered under the
     Securities Act of 1933, as amended. The transfer of such security is
     subject to the restrictions on transfer specified in the Purchase
     Agreement, dated December 16, 1997 (as amended and modified from
     time to time), between the issuer hereof (the "Company") and the
     initial holder hereof, and the Company reserves the right to refuse
     the transfer of such security until such conditions have been
     fulfilled. Upon written request, a copy of such conditions shall be
     furnished by the Company to the holder hereof without charge.


                              HINES HOLDINGS, INC.
                             STOCK PURCHASE WARRANT
                             ----------------------


Date of Issuance:  December 16, 1997                         Certificate No. W-6


          FOR VALUE RECEIVED, Hines Holdings, Inc., a Nevada corporation (the
"Company"), hereby grants to Madison Dearborn Capital Partners, L.P. (the
"Registered Holder") the right to purchase from the Company 104,282 shares of
the Company's Common Stock, par value $.01 per share, at a price per share of
$.01 (as adjusted from time to time in accordance herewith, the "Exercise
Price").  This Warrant is subject to the terms and provisions regarding the
transfer of restricted securities contained in the Purchase Agreement, dated as
of the date hereof (the "Purchase Agreement"), between the Company and certain
persons named therein.  Certain capitalized terms used herein are defined in
Section 4 hereof.  The amount and kind of securities obtainable pursuant to the
rights granted hereunder and the purchase price for such securities are subject
to adjustment pursuant to the provisions contained in this Warrant.

          This Warrant is subject to the following provisions:

          Section 1.     Exercise of Warrant.

          1A.  Exercise Period.  The Registered Holder may exercise, in whole or
in part, the purchase rights represented by this Warrant at any time and from
time to time prior to the earlier of (i) the tenth anniversary of the date
hereof,  (ii) a Qualified Public Offering or (iii) a Sale of the Company (the
"Exercise Period").  The Company shall give the Registered Holder written notice
of the expiration of the Exercise Period at least 10 days but not more than 90
days prior to the end of the Exercise Period.

          1B.  Exercise Procedure.
<PAGE>

          (i) This Warrant shall be deemed to have been exercised when the
Company has received all of the following items (the "Exercise Time"):

          (a) a completed Exercise Agreement, as described in paragraph 1C
     below, executed by the Person exercising all or part of the purchase rights
     represented by this Warrant (the "Purchaser");

          (b)  this Warrant;

          (c) if this Warrant is not registered in the name of the Purchaser, an
     Assignment or Assignments in the form set forth in Exhibit II hereto
     evidencing the assignment of this Warrant to the Purchaser, in which case
     the Registered Holder shall have complied with the provisions set forth in
     Section 5 hereof; and

          (d) either (1) a check payable to the Company in an amount equal to
     the product of the Exercise Price multiplied by the number of shares of
     Common Stock being purchased upon such exercise (the "Aggregate Exercise
     Price"), (2) the surrender to the Company of debt or equity securities of
     the Company having a Market Value equal to the Aggregate Exercise Price of
     the Common Stock being purchased upon such exercise (provided that for
     purposes of this subparagraph, the Market Value of any note or other debt
     security or any preferred stock shall be deemed to be equal to the
     aggregate outstanding principal amount or liquidation value thereof plus
     all accrued and unpaid interest thereon or accrued or declared and unpaid
     dividends thereon) or (3) a written notice to the Company that the
     Purchaser is exercising the Warrant (or a portion thereof) by authorizing
     the Company to withhold from issuance a number of shares of Common Stock
     issuable upon such exercise of the Warrant which when multiplied by the
     Market Value of the Common Stock is equal to the Aggregate Exercise Price
     (and such withheld shares shall no longer be issuable under this Warrant).

          (ii)  Certificates for shares of Common Stock purchased upon exercise
of this Warrant shall be delivered by the Company to the Purchaser within 5
business days after the date of the Exercise Time.  Unless this Warrant has
expired or all of the purchase rights represented hereby have been exercised,
the Company shall prepare a new Warrant, substantially identical hereto,
representing the rights formerly represented by this Warrant which have not
expired or been exercised and shall, within such 5 business day period, deliver
such new Warrant to the Person designated for delivery in the Exercise
Agreement.

          (iii) The Common Stock issuable upon the exercise of this Warrant
shall be deemed to have been issued to the Purchaser at the Exercise Time, and
the Purchaser shall be deemed for all purposes to have become the record holder
of such Common Stock at the Exercise Time.

          (iv) The issuance of certificates for shares of Common Stock upon
exercise of this Warrant shall be made without charge to the Registered Holder
or the Purchaser for any issuance tax in respect thereof or other cost incurred
by the Company in connection with such exercise and the

                                       2
<PAGE>

related issuance of shares of Common Stock. Each share of Common Stock issuable
upon exercise of this Warrant shall, upon payment of the Exercise Price
therefor, be fully paid and nonassessable and free from all liens and charges
with respect to the issuance thereof.

          (v) The Company shall not close its books against the transfer of this
Warrant or of any share of Common Stock issued or issuable upon the exercise of
this Warrant in any manner which interferes with the timely exercise of this
Warrant.

          (vi) The Company shall assist and cooperate with any Registered Holder
or Purchaser required to make any governmental filings or obtain any
governmental approvals prior to or in connection with any exercise of this
Warrant (including, without limitation, making any filings required to be made
by the Company).

          (vii) Notwithstanding any other provision hereof, if an exercise of
any portion of this Warrant is to be made in connection with a registered public
offering or the sale of the Company, the exercise of any portion of this Warrant
may, at the election of the holder hereof, be conditioned upon the consummation
of the public offering or sale of the Company in which case such exercise shall
not be deemed to be effective until the consummation of such transaction.

          (viii) The Company shall at all times reserve and keep available out
of its authorized but unissued shares of Common Stock solely for the purpose of
issuance upon the exercise of the Warrants, such number of shares of Common
Stock issuable upon the exercise of all outstanding Warrants. All shares of
Common Stock which are so issuable shall, when issued, be duly and validly
issued, fully paid and nonassessable and free from all taxes, liens and charges.
The Company shall take all such actions as may be necessary to assure that all
such shares of Common Stock may be so issued without violation of any applicable
law or governmental regulation or any requirements of any domestic securities
exchange upon which shares of Common Stock may be listed (except for official
notice of issuance which shall be immediately delivered by the Company upon each
such issuance). The Company shall not take any action which would cause the
number of authorized but unissued shares of Common Stock to be less than the
number of such shares required to be reserved hereunder for issuance upon
exercise of the Warrant.

          1C.  Exercise Agreement.  Upon any exercise of this Warrant, the
Exercise Agreement shall be substantially in the form set forth in Exhibit I
hereto, except that if the shares of Common Stock are not to be issued in the
name of the Person in whose name this Warrant is registered, the Exercise
Agreement shall also state the name of the Person to whom the certificates for
the shares of Common Stock are to be issued, and if the number of shares of
Common Stock to be issued does not include all the shares of Common Stock
purchasable hereunder, it shall also state the name of the Person to whom a new
Warrant for the unexercised portion of the rights hereunder is to be delivered.
Such Exercise Agreement shall be dated the actual date of execution thereof.

          Section 2.  Adjustment of Exercise Price and Number of Shares.  In
order to prevent dilution of the rights granted under this Warrant, the Exercise
Price shall be subject to adjustment from time to time as provided in this
Section 2, and the number of shares of Common Stock obtainable upon exercise of
this Warrant shall be subject to adjustment from time to time as provided in
this Section 2.

                                       3
<PAGE>

          2A.  Subdivision or Combination of Common Stock.  If the Company at
any time subdivides (by any stock split, stock dividend, recapitalization or
otherwise) one or more classes of its outstanding shares of Common Stock into a
greater number of shares, the Exercise Price in effect immediately prior to such
subdivision shall be proportionately reduced and the number of shares of Common
Stock obtainable upon exercise of this Warrant shall be proportion  ately
increased.  If the Company at any time combines (by reverse stock split or
otherwise) one or more classes of its outstanding shares of Common Stock into a
smaller number of shares, the Exercise Price in effect immediately prior to such
combination shall be proportionately increased and the number of shares of
Common Stock obtainable upon exercise of this Warrant shall be proportionately
decreased.

          2B.  Reorganization, Reclassification, Consolidation, Merger or Sale.
Any recapitalization, reorganization, reclassification, consolidation, merger,
sale of all or substantially all of the Company's assets or other transaction,
in each case which is effected in such a way that the holders of Common Stock
are entitled to receive (either directly or upon subsequent liquidation) stock,
securities or assets with respect to or in exchange for Common Stock is referred
to herein as an "Organic Change."  Prior to the consummation of any Organic
Change, the Company shall make appropriate provision (in form and substance
reasonably satisfactory to the Registered Holders of the Warrants representing a
majority of the Common Stock obtainable upon exercise of all Warrants then
outstanding) to insure that each of the Registered Holders of the Warrants shall
thereafter have the right to acquire and receive, in lieu of or in addition to
(as the case may be) the shares of Common Stock immediately theretofore
acquirable and receivable upon the exercise of such holder's Warrant, such
shares of stock, securities 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 such holder's Warrant had
such Organic Change not taken place.  In any such case, the Company shall make
appropriate provision (in form and substance reasonably satisfactory to the
Registered Holders of the Warrants representing a majority of the Common Stock
obtainable upon exercise of all Warrants then outstanding) with respect to such
holders' rights and interests to insure that the provisions of this Section 2
shall thereafter be applicable to the Warrants (including, in the case of any
such consolidation, merger or sale in which the successor entity or purchasing
entity is other than the Company, an immediate adjustment of the Exercise Price,
and a corresponding immediate adjustment in the number of shares of Common Stock
acquirable and receivable upon exercise of the Warrants). The Company shall not
effect any such consolidation, merger or sale, unless prior to the consummation
thereof, the successor entity (if other than the Company) resulting from
consolidation or merger or the entity purchasing such assets assumes by written
instrument (in form and substance satisfactory to the Registered Holders of
Warrants representing a majority of the Common Stock obtainable upon exercise of
all of the Warrants then outstanding) the obligation to deliver to each such
holder such shares of stock, securities or assets as, in accordance with the
foregoing provisions, such holder may be entitled to acquire.

          2C.  Certain Events.  If any event occurs of the type contemplated by
the provisions of this Section 2 but not expressly provided for by such
provisions then the Company's board of directors shall make an appropriate
adjustment in the Exercise Price and the number of shares of Common Stock
obtainable upon exercise of this Warrant so as to protect the rights of the
holders of the Warrants.

                                       4
<PAGE>

          2D.  Notices.

          (i) Immediately upon any adjustment of the Exercise Price, the Company
shall give written notice thereof to the Registered Holder, setting forth in
reasonable detail and certifying the calculation of such adjustment.

          (ii) The Company shall give written notice to the Registered Holder at
least 20 days prior to the date on which the Company closes its books or takes a
record (A) with respect to any dividend or distribution upon the Common Stock,
(B) with respect to any pro rata subscription offer to holders of Common Stock
or (C) for determining rights to vote with respect to any Organic Change,
dissolution or liquidation.

          (iii) The Company shall also give written notice to the Registered
Holders at least 20 days prior to the date on which any Organic Change,
dissolution or liquidation shall take place.

          Section 3.  Definitions.  The following terms have the meanings set
forth below:

          "Affiliate" of any particular Person means any other Person
controlling, controlled by or under common control with such particular Person,
where "control" means the possession, directly or indirectly, of the power to
direct the management and policies of a Person whether through the ownership of
voting securities, contract or otherwise.

          "Common Stock" means shares of the Company's Common Stock, par
value $.01 per share.

          "Independent Third Party" means any Person who, immediately prior to
the contemplated transaction, does not own in excess of 5%, on a fully-diluted
basis, of the Company's voting capital stock (a "5% Owner"), who is not
controlling, controlled by or under common control with any such 5% Owner and
who is not the spouse or descendent (by birth or adoption) of any such 5% Owner
or a trust for the benefit of such 5% Owner and/or such other Persons.

          "Market Value" as to any security means the fair market value of such
security as determined by the board of directors of the Company in its
reasonable good faith judgment.

          "Person" means an individual, a partnership, a corporation, a limited
liability company, an association, a joint stock company, a trust, a joint
venture, an unincorporated organization and a governmental entity or any
department, agency or political subdivision thereof.

          "Purchase Agreement" has the meaning set forth in the preamble.

          "Qualified Public Offering" means the sale in an underwritten public
offering registered under the Securities Act of 1933, as amended, of shares of
the Company's Common Stock having an aggregate offering value of at least $10
million.

          "Sale of the Company" means the sale of the Company to an Independent
Third Party or group of Independent Third Parties pursuant to which such party
or parties acquire

                                       5
<PAGE>

(i) capital stock of the Company possessing the voting power under normal
circumstances to elect a majority of the Company's board of directors (whether
by merger, consolidation or sale or transfer of the Company's capital stock) or
(ii) all or substantially all of the Company's assets determined on a
consolidated basis.

          Section 4.  No Voting Rights; Limitations of Liability.  This Warrant
shall not entitle the holder hereof to any voting rights or other rights as a
stockholder of the Company.  No provision hereof, in the absence of affirmative
action by the Registered Holder to purchase Common Stock, and no enumeration
herein of the rights or privileges of the Registered Holder shall give rise to
any liability of such holder for the Exercise Price of Common Stock acquirable
by exercise hereof or as a stockholder of the Company.

          Section 5.  Warrant Not Transferable.  Except as expressly provided
herein or in the Purchase Agreement, this Warrant, the Common Stock issued upon
exercise hereof and all rights hereunder are transferable, in whole or in part,
by the holder hereof only to its Affiliates; provided that any Affiliate to whom
this Warrant is transferred agrees to be bound in all respects to the provisions
hereof and of the Purchase Agreement, including, without limitation,
restrictions on the transfer of this Warrant.  Subject to the transfer
conditions contained herein and in the Purchase Agreement, this Warrant and all
rights hereunder may be transferred upon surrender of this Warrant with a
properly executed Assignment (in the form of Exhibit II hereto) at the principal
office of the Company.

          Section 6.  Warrant Exchangeable for Different Denominations.  This
Warrant is exchangeable, upon the surrender hereof by the Registered Holder at
the principal office of the Company, for new Warrants of like tenor representing
in the aggregate the purchase rights hereunder, and each of such new Warrants
shall represent such portion of such rights as is designated by the Registered
Holder at the time of such surrender.  The date the Company initially issued
this Warrant shall be deemed to be the "Date of Issuance" hereof regardless of
the number of times new certificates representing the unexpired and unexercised
rights formerly represented by this Warrant shall be issued.  All Warrants
representing portions of the rights hereunder are referred to herein as the
"Warrants."

          Section 7.  Replacement.  Upon receipt of evidence reasonably
satisfactory to the Company (an affidavit of the Registered Holder shall be
satisfactory) of the ownership and the loss, theft, destruction or mutilation of
any certificate evidencing this Warrant, and in the case of any such loss, theft
or destruction, upon receipt of indemnity reasonably satisfactory to the
Company, or, in the case of any such mutilation upon surrender of such
certificate, the Company shall (at its expense) execute and deliver in lieu of
such certificate a new certificate of like kind representing the same rights
represented by such lost, stolen, destroyed or mutilated certificate and dated
the date of such lost, stolen, destroyed or mutilated certificate.

          Section 8.  Notices.  Except as otherwise expressly provided herein,
all notices referred to in this Warrant shall be in writing and shall be
delivered personally or sent by registered or certified mail, return receipt
requested, postage prepaid and shall be deemed to have been given when so
delivered or deposited in the U.S. Mail (i) to the Company, at its principal
executive offices

                                       6
<PAGE>

and (ii) to the Registered Holder of this Warrant, at such holder's address as
it appears in the records of the Company (unless otherwise indicated by such
holder).

          Section 9.  Amendment and Waiver.  Except as otherwise provided
herein, the provisions of the Warrants may be amended and the Company may take
any action herein prohibited, or omit to perform any act herein required to be
performed by it, only if the Company has obtained the written consent of the
Registered Holders of Warrants representing a majority of the shares of Common
Stock obtainable upon exercise of the Warrants; provided that no such action may
change the Exercise Price of the Warrants or the number of shares issuable upon
exercise of the Warrants without the prior written consent of registered holders
representing at least 95% of the shares of Common Stock obtainable upon exercise
of all of the warrants issued under the Purchase Agreement; and provided
further, no amendment shall be enforceable against one holder of Warrants
without also being enforceable against all other holders of Warrants.  In
exercising its rights hereunder, the Company shall exercise such rights in the
same manner with respect to each holder of Warrants.  The Company shall not
enter into any other agreement or conduct any course of dealing which alters the
rights or obligations of any holder of Warrants with respect thereto without
first offering to each other holder of Warrants the opportunity to enter into
such agreement or course of dealing.

          Section 10.  Descriptive Headings.  The descriptive headings of the
several Sections and paragraphs of this Warrant are inserted for convenience
only and do not constitute a part of this Warrant.

          Section 11.   Governing Law.  All issues and questions concerning the
construction, validity, enforcement and interpretation of this Agreement and the
exhibits and schedules hereto shall be governed by, and construed in accordance
with, the laws of the State of Nevada, without giving effect to any choice of
law or conflict of law rules or provisions (whether of the State of Nevada or
any other jurisdiction) that would cause the application of the laws of any
jurisdiction other than the State of Nevada.

                              *     *     *     *

                                       7
<PAGE>

          IN WITNESS WHEREOF, the Company has caused this Warrant to be signed
and attested by its duly authorized officers under its corporate seal and to be
dated the Date of Issuance hereof.


                                        HINES HOLDINGS, INC.


                                        By: /s/ Paul R. Wood

                                        Its: President


Attest:


By: /s/ Paul R. Wood

Hines Holdings, Inc., Secretary

                                       8
<PAGE>

                                                                       EXHIBIT I

                              HINES HOLDINGS, INC.
                           WARRANT EXERCISE AGREEMENT
                           --------------------------


To:                                                     Dated:

          The undersigned, pursuant to the provisions set forth in the attached
Warrant (Certificate No. W-1) hereby agrees to subscribe for the purchase of
______ shares of the Common Stock covered by such Warrant and makes payment
herewith in full therefor at the price per share provided by such Warrant.


                                        Signature ____________________

                                        Address ______________________



                                                                      EXHIBIT II

                                   ASSIGNMENT
                                   ----------


          FOR VALUE RECEIVED, _____________________________ hereby sells,
assigns and transfers all of the rights of the undersigned under the attached
Warrant (Certificate No. W-_____) with respect to the number of shares of the
Common Stock covered thereby set forth below, unto:

Names of Assignee                 Address                      No. of Shares
-----------------                 -------                      -------------







Dated:                                  Signature  _______________________

                                                   _______________________

                                        Witness    _______________________

                                       9