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                                                                    Exhibit 4.20

                                     Stock Subscription Warrant to Subscribe for
                                                  600,000 Shares of Common Stock


Stock Subscription Warrant No. A-1

          THIS STOCK SUBSCRIPTION WARRANT AND ANY SHARES ACQUIRED UPON THE
EXERCISE OF THIS STOCK SUBSCRIPTION WARRANT HAVE NOT BEEN REGISTERED UNDER THE
SECURITIES ACT OF 1933, AS AMENDED. NEITHER THIS STOCK SUBSCRIPTION WARRANT NOR
ANY OF SUCH SHARES MAY BE SOLD OR TRANSFERRED IN THE ABSENCE OF SUCH
REGISTRATION OR AN EXEMPTION THEREFROM UNDER SAID ACT.


                          STOCK SUBSCRIPTION WARRANT

                     To Subscribe for and Purchase Shares
                              of Common Stock of

                             GRUBB & ELLIS COMPANY

                   THIS CERTIFIES THAT, for value received,

          AEGON USA REALTY ADVISORS, INC. or registered assigns, is entitled to
subscribe for and purchase from GRUBB & ELLIS COMPANY (herein called the
"Company"), a corporation organized and existing under the laws of the State of
Delaware, at any time or from time to time during the period specified in
paragraph 2 hereof, up to

                             SIX HUNDRED THOUSAND

fully paid and nonassessable shares of the Company's common stock, par value
$0.01 per share (the "Common Stock"), at an exercise price per share of $6.25
(the "Exercise Price").  The number of shares purchasable hereunder and the
Exercise Price are subject to adjustment as provided in paragraph 4 hereof.  The
term "Warrant," as used herein, shall mean this Stock Subscription Warrant,
including all amendments hereto.  The term "Warrant Shares," as used herein,
refers to the shares purchasable upon the exercise of the Warrants.

          Certain terms used herein and not elsewhere defined are defined in
paragraph 15 hereof.

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

          1.   Manner of Exercise; Issuance of Certificates; Payment for Shares.
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The rights represented by this Warrant may be exercised by the holder hereof in
whole or in part (but not as to a fractional Warrant Share), by the surrender of
this Warrant, together with a completed Exercise
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Agreement in the form attached hereto, during normal business hours on any
business day at the principal office of the Company (or such other office or
agency of the Company in New York, New York or Chicago, Illinois as it may
designate by notice in writing to the holder hereof at the address of such
holder appearing on the books of the Company) at any time during the period set
forth in paragraph 2 hereof and upon payment to the Company by certified check
or bank draft of the Exercise Price for such shares, or, at the election of the
holder hereof, by delivery of other Warrants equal in value to the aggregate
Exercise Price with respect to such Warrants being exercised, the value of which
other Warrants shall be deemed to equal the difference between the Market Price
of a share of Common Stock on the date immediately preceding the date of
exercise and the then current Exercise Price. The Company agrees that the shares
so purchased shall be and are deemed to be issued to the holder hereof or its
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 and payment made for such
shares as aforesaid. Certificates for the Warrant Shares so purchased,
representing the aggregate number of shares specified in said Exercise
Agreement, shall be delivered to the holder hereof within a reasonable time, not
exceeding five business days, after the rights represented by this Warrant shall
have been so exercised. Each stock certificate so delivered shall be in such
denominations as may be requested by the holder hereof and shall be registered
in the name of said holder or such other name (upon compliance with the transfer
requirements hereinafter set forth) as shall be designated by said holder. If
this Warrant shall have been exercised only in part, then, unless this Warrant
has expired, the Company shall, at its expense, at the time of delivery of said
stock certificates, deliver to said holder a new Warrant representing the number
of shares with respect to which this Warrant shall not then have been exercised.
The Company shall pay all taxes and other expenses and charges payable in
connection with the preparation, execution and delivery of stock certificates
(and any new Warrants) pursuant to this paragraph except that, in case such
stock certificates shall be registered in a name or names other than the holder
of this Warrant or its nominee, funds sufficient to pay all stock transfer taxes
which shall be payable in connection with the execution and delivery of such
stock certificates shall be paid by the holder hereof to the Company at the time
of the delivery of such stock certificates by the Company as mentioned above.

          2.   Period of Exercise.  This Warrant is exercisable at any time or
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from time to time prior to July 31, 2004.

          3.   Shares to be Fully Paid; Reservation of Shares.  The Company
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covenants and agrees that all Warrant Shares will, upon issuance, be fully paid
and nonassessable and free from preemptive rights and all taxes, liens and
charges with respect to the issue thereof; and without limiting the generality
of the foregoing, the Company covenants and agrees that it will from time to
time take all such action as may be required to assure that the par value per
Warrant Share is at all times equal to or less than the effective Exercise
Price. The Company further covenants and agrees that during the period within
which the rights represented by this Warrant may be exercised, the Company will
at all times have authorized, and reserved for the purpose of issue upon
exercise of the subscription rights evidenced by this Warrant, a sufficient
number of shares of Common Stock to provide for the exercise of the rights
represented by this Warrant. The Company shall take all such action as may be
necessary to assure that such shares of Common Stock may be so issued without
violation of any applicable law or regulation and will be approved for listing
on any domestic securities exchange upon which the Common Stock may be listed.
The Company further

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covenants and agrees that it will, at any time, at its expense, promptly list on
each national securities exchange on which any Capital Stock is at the time
listed, upon official notice of issuance, Common Stock issuable upon the
exercise of any Warrant as provided in paragraph 1 hereof, and maintain such
listing of all shares of Common Stock from time to time issuable upon such
exercise, and will, at any time, register under the Securities Exchange Act of
1934, as amended, all shares of Common Stock from time to time issuable upon
such exercise if and at the time that any existing shares of Capital Stock are
so registered.

          4.   Anti-dilution Provisions.  The Exercise Price set forth above
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shall be subject to adjustment from time to time as hereinafter provided. For
purposes of this paragraph 4, the term "Capital Stock" as used herein includes
the Company's Common Stock and shall also include any capital stock of any class
of the Company hereafter authorized which shall not be limited to a fixed sum or
percentage in respect of the rights of the holders thereof to participate in
dividends and in the distribution of assets upon the voluntary or involuntary
liquidation, dissolution or winding up of the Company; provided that the shares
purchasable pursuant to this Warrant shall include only Common Stock. Upon each
adjustment of the Exercise Price, this Warrant shall thereafter represent the
right to purchase, at the Exercise Price resulting from such adjustment, the
largest number of shares of Common Stock obtained by multiplying the Exercise
Price in effect immediately prior to such adjustment by the number of shares of
Common Stock purchasable thereunder immediately prior to such adjustment and
dividing the product thereof by the Exercise Price resulting from such
adjustment.

          In case the Company, at any time, shall be a party to any Transaction,
each holder hereof, upon the exercise hereof at any time on or after the
Consummation Date shall be entitled to receive, and this Warrant shall
thereafter represent the right to receive, in lieu of the Common Stock issuable
upon exercise prior to the Consummation Date, the kind and amount of securities
or property (including cash) which it would have owned or have been entitled to
receive after the happening of such Transaction had this Warrant been exercised
immediately prior to such Transaction.

          Notwithstanding anything contained herein to the contrary, the Company
shall not effect any Transaction unless prior to the consummation thereof each
corporation or entity (other than the Company) which may be required to deliver
any securities or other property upon the exercise of Warrants, the surrender of
Warrants or the satisfaction of exercise rights as provided herein, shall
assume, by written instrument delivered to each holder of Warrants, the
obligation to deliver to such holder such securities or other property to which,
in accordance with the foregoing provisions, such holder may be entitled, and
such corporation or entity shall have similarly delivered to each holder of
Warrants an opinion of counsel for such corporation or entity, satisfactory to
each holder of Warrants, which opinion shall state that all the outstanding
Warrants, including, without limitation, the exercise provisions applicable
thereto, if any, shall thereafter continue in full force and effect and shall be
enforceable against such corporation or entity in accordance with the terms
hereof and thereof and, together with such other matters as such holders may
reasonably request.

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          In case the Company shall (i) pay a dividend in shares of Capital
Stock or securities convertible into Capital Stock or make a distribution to all
holders of shares of Capital Stock in shares of Capital Stock or securities
convertible into Capital Stock, (ii) subdivide its outstanding shares of Capital
Stock, (iii) combine its outstanding shares of Capital Stock into a smaller
number of shares of Capital Stock or (iv) issue by reclassification of its
shares of Capital Stock other securities of the Corporation, the Exercise Price
shall be adjusted (to the nearest cent) by multiplying the Exercise Price
immediately prior to such adjustment by a fraction, of which the numerator shall
be the number of shares of Capital Stock outstanding immediately prior to the
occurrence of such event, and of which the denominator shall be the number of
shares of Capital Stock outstanding (including any convertible securities issued
pursuant to clause (i) or (iv) above on an as converted basis) immediately
thereafter. An adjustment made pursuant to the foregoing sentence shall become
effective immediately after the effective date of such event retroactive to the
record date, if any, for such event.

          (b)   Notice of Adjustment.  Upon the occurrence of any event
                --------------------
requiring an adjustment of the Exercise Price, then and in each such case the
Company shall promptly deliver to each holder of Warrants a certificate signed
by the President or any Vice President and the Secretary or any Assistant
Secretary of the Company (an "Officers' Certificate") stating the Exercise Price
resulting from such adjustment and the increase or decrease, if any, in the
number of shares of Common Stock issuable upon exercise of the Warrants, setting
forth in reasonable detail the method of calculation and the facts upon which
such calculation is based. Within 90 days after each fiscal year in which any
such adjustment shall have occurred, or within 30 days after any request
therefor by any holder of Warrants stating that such holder contemplates
exercise of such Warrants, the Company will obtain and deliver to each holder of
Warrants the opinion of its regular independent auditors or another firm of
independent public accountants of recognized national standing selected by the
Company's Board of Directors who are satisfactory to the registered holder of
this Warrant, which opinion shall confirm the statements in the most recent
Officers' Certificate delivered under this paragraph 4(d).

          (c)   Other Notices.  In case at any time:
                -------------

          (i)   the Company shall declare or pay to the holders of Capital Stock
     any dividend other than a regular periodic cash dividend or any periodic
     cash dividend in excess of 115% of the cash dividend for the comparable
     fiscal period in the immediately preceding fiscal year;

          (ii)  the Company shall declare or pay any dividend upon Capital Stock
     payable in stock or make any special dividend or other distribution (other
     than regular cash dividends) to the holders of Capital Stock;

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

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

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

          (vi)  there shall be any other Transaction;

then, in any one or more of such cases, the Company shall give to the holder of
each Warrant (a) at least 15 days prior to any event referred to in clause (i)
or (ii) above, at least 30 days prior to any event referred to in clause (iii),
(iv) or (v) above, and within five business days after it has knowledge of any
pending Transaction, written notice of the date on which the books of the
Company shall close or a record shall be taken for such dividend, distribution
or subscription rights or for determining rights to vote in respect of any such
reorganization, reclassification, consolidation, merger, sale, dissolution,
liquidation, winding-up or Transaction and (b) in the case of any such
reorganization, reclassification, consolidation, merger, sale, dissolution,
liquidation, winding-up or Transaction known to the Company, at least 30 days
prior written notice of the date (or, if not then known, a reasonable
approximation thereof by the Company) when the same shall take place.  Such
notice in accordance with the foregoing clause (a) shall also specify, in the
case of any such dividend, distribution or subscription rights, the date on
which the holders of Capital Stock shall be entitled thereto, and such notice in
accordance with the foregoing clause (b) shall also specify the date on which
the holders of Capital Stock shall be entitled to exchange their Capital Stock
for securities or other property deliverable upon such reorganization,
reclassification, consolidation, merger, sale, dissolution, liquidation,
winding-up or Transaction, as the case may be.  Such notice shall also state
that the action in question or the record date is subject to the effectiveness
of a registration statement under the Securities Act (a "Registration
Statement") or to a favorable vote of security holders, if either is required.
Any exercise of the Warrant may be made conditioned by the holder thereof upon
the consummation of any of the events described in clauses (i) through (iv)
above.

          5.   Certain Agreements of the Company.  The Company covenants and
               ---------------------------------
agrees that:

          (a)  Certain Actions Prohibited.  The Company will not by amendment of
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its certificate of incorporation 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 hereunder by the Company, 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 any Warrant in order to protect the exercise rights of the
holders of the Warrants. 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 the Warrants above the Exercise Price then in
effect, (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 all Warrants from time
to time outstanding, (iii) will not take any action which results in

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any adjustment of the number of shares of Common Stock issuable after the action
upon the exercise of all of the Warrants if, as a result of such adjustment, the
number of shares of Common Stock issuable upon exercise of all the Warrants
would exceed the total number of shares of Common Stock then authorized by the
Company's certificate of incorporation and available for the purpose of issue
upon such exercise, and (iv) will not issue any capital stock of any class which
has the right to more than one vote per share or any capital stock of any class
which is preferred as to dividends or as to the distribution of assets upon
voluntary or involuntary dissolution, liquidation or winding-up, unless the
rights of the holders thereof shall be limited to a fixed sum or percentage (or
floating rate related to market yields) of par value or stated value in respect
of participation in dividends and a fixed sum or percentage of par value or
stated value in any such distribution of assets.

          (b)  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.

          (c)  Issuance of Warrant Securities.  If the issuance of any Warrant
               ------------------------------
Shares required to be reserved for purposes of exercise of this Warrant or for
the conversion of such Warrant Shares requires registration with or approval of
any Federal governmental authority under any Federal or state law (other than
any registration under the Securities Act) or listing on any national securities
exchange, before such shares may be issued upon exercise of this Warrant, the
Company will, at its expense, use its best efforts to cause such shares to be
duly registered or approved, or listed on the relevant national securities
exchange, as the case may be, at such time, so that such shares may be issued in
accordance with the terms hereof and so converted.

          6.   Issue Tax.  The issuance of certificates for Warrant Shares upon
               ---------
the exercise of Warrants shall be made without charge to the holders of such
Warrants or such shares for any issuance tax 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 the Warrant exercised.

          7.   Closing of Books.  The Company will at no time close its
               ----------------
transfer books against the transfer of any Warrant, of any Warrant Shares issued
or issuable upon the exercise of any Warrant or in any manner which interferes
with the timely exercise of this Warrant.

          8.   Amendments to Terms of Warrant Shares.  The Company will not
               -------------------------------------
amend the terms of the Warrant Shares in any manner that would treat the Warrant
Shares differently from other shares of the Company's Common Stock.

          9.   Availability of Information.  The Company will cooperate with
               ---------------------------
each holder of any Warrants or Warrant Shares in supplying such information as
may be necessary for such holder to complete and file any information reporting
forms presently or hereafter required by the Securities and Exchange Commission
as a condition to the availability of an exemption from the Securities Act for
the sale of any Warrants or Warrant Shares. The Company will deliver to any
person at the time holding any Warrants, promptly upon their becoming available,
copies of all

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financial statements, reports, notices and proxy statements sent or made
available generally by the Company to its stockholders, and copies of all
regular and periodic reports and all registration statements and prospectuses
filed by the Company with any securities exchange or with the Securities and
Exchange Commission.

          10.  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.

          11.  Transfer and Exchange.
               ---------------------

          (a)  (1) The transfer of this Warrant and all rights hereunder, in
whole or in part, is registrable at the office or agency of the Company referred
to below by the holder hereof in person or by his duly authorized attorney, upon
surrender of this Warrant properly endorsed. Each taker and holder of this
Warrant, by taking or holding the same, consents and agrees that this Warrant,
when endorsed in blank, shall be deemed negotiable, and that the holder hereof,
when this Warrant shall have been so endorsed, may be treated by the Company and
all other persons dealing with this Warrant as the absolute owner and holder
hereof for any purpose and as the person entitled to exercise the rights
represented by this Warrant, or to the registration of transfer hereof on the
books of the Company; and until due presentment for registration of transfer on
such books the Company may treat the registered holder hereof as the owner and
holder for all purposes, and the Company shall not be affected by notice to the
contrary.

          (2)  The holder of this Warrant, by acceptance hereof, understands
that the Warrant Securities are characterized as "restricted securities" under
the federal securities laws inasmuch as they are being or will be acquired from
the Company in a transaction not involving a public offering and that under such
laws and applicable regulations such Warrant Securities may be resold without
registration under the Securities Act only in certain limited circumstances. The
holder of this Warrant, by acceptance hereof, agrees to comply with all
applicable laws (including, without limitation, any filing required by the Hart-
Scott-Rodino Antitrust Improvements Act of 1976) upon exercise hereof.

          The holder of this Warrant, by acceptance hereof, represents that such
holder is acquiring this Warrant and any Warrant Shares to be issued upon
exercise hereof for its own account (including any separate account) for the
purpose of investment and not with a view to or for sale in connection with any
distribution thereof. The holder hereof further represents that such holder has
had an opportunity to ask questions and receive answers from the Company
regarding the terms and conditions of the offering of the Warrant Securities as
required by Section (b)(2)(v) of Rule 502 of Regulation D under the Securities
Act.

          Without in any way limiting the foregoing, the holder hereof further
agrees not to make any disposition of all or any portion of the Warrant
Securities unless and until:

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          (x)  There is then in effect a Registration Statement under the
Securities Act covering such proposed disposition and such disposition is
made in accordance with such Registration Statement; or

          (y)  Such disposition is made in conformity with the limitations of
Rule 144 under the Securities Act or similar rule as then in effect under the
Securities Act; or

          (z)  (i) The holder hereof shall have notified the Company of the
proposed disposition and shall have furnished the Company with a detailed
statement of the circumstances surrounding the proposed disposition, and (ii)
shall have furnished the Company with an opinion of counsel, reasonably
satisfactory to the Company (it being understood that if the holder of this
Warrant is a party to the Agreement, counsel who is such party's employee shall
be deemed reasonably satisfactory to the Company), that such disposition will
not require registration of such Warrant Securities under the Securities Act.

          (b)  Register.  The Company shall maintain, at the principal office
               --------
of the Company (or such other office or agency of the Company in New York, New
York or Chicago, Illinois as it may designate by notice to the holder hereof), a
register for the Warrants, in which the Company shall record the name and
address of the person in whose name a Warrant has been issued, as well as the
name and address of each transferee and each prior owner of such Warrant. Within
10 days after any holder of Warrants shall by notice request the same, the
Company will deliver to such holder a certificate, signed by one of its
officers, listing the name and address of every other holder of Warrants and/or
Warrant Shares, as such information appears in said register and in the stock
transfer books of the Company at the close of business on the day before such
certificate is signed.

          (c)  Warrants 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 paragraph 10(b), for new Warrants
of like tenor representing in the aggregate the right to subscribe for and
purchase the number of shares which may be subscribed for and purchased
hereunder of Common Stock, each of such new Warrants to represent the right to
subscribe for and purchase such number of shares as shall be designated by said
holder hereof at the time of such surrender.

          (d)  Replacement of Warrants.  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 bond (or, in the case of any institutional holder, 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 such
Warrant, the Company at its expense will execute and deliver, in lieu thereof, a
new Warrant of like tenor.

          (e)  Cancellation; Payment of Expenses.  Upon the surrender of this
               ---------------------------------
Warrant in connection with any exchange, transfer or replacement as provided in
this paragraph 10, this Warrant shall be promptly canceled by the Company. The
Company shall pay all taxes (other than

                                       8
<PAGE>

securities transfer taxes) and all other expenses and charges payable in
connection with the preparation, execution and delivery of Warrants pursuant to
this paragraph 10.

          12.  Registration Rights.  The Company covenants and agrees as
               -------------------
follows:

          (a)  Definitions.  For purposes of this paragraph 11:
               -----------

          The term "Registrable Securities" means (i) the Common Stock issued
pursuant to this Warrant and (ii) any Common Stock of the Company issued
pursuant to a stock dividend, stock split or other distribution, merger,
consolidation, recapitalization or reclassification or otherwise, and any
securities of the Company which may be issued or distributed with respect to, or
in exchange for, any such Common Stock or such other securities pursuant to a
stock dividend, stock split or other distribution, merger, consolidation,
recapitalization or reclassification or otherwise; provided, however, that any
such Registrable Securities shall cease to be Registrable Securities when (i) a
Registration Statement with respect to the sale of such Registrable Securities
has been declared effective under the Securities Act and such Registrable
Securities have been disposed of in accordance with the plan of distribution set
forth in such Registration Statement, (ii) such Registrable Securities are
distributed pursuant to Rule 144 (or any similar provision then in force) under
the Securities Act or (iii) such Registrable Securities shall have been
otherwise transferred, new certificates for them not bearing a legend
restricting further transfer under the Securities Act shall have been delivered
by the Company and they may be resold without subsequent registration under the
Securities Act; provided, further, however, that any securities that have ceased
to be Registrable Securities cannot thereafter become Registrable Securities,
and any security that is issued or distributed in respect to securities that
have ceased to be Registrable Securities are not Registrable Securities.

          (b)  Grant of Rights. The Company hereby grants to the holder
               ---------------
registration rights as follows (the "Registration Rights"):

          (1)  Piggyback Registrations. Subject to paragraph 11(b)(2) hereof, if
at any time and from time to time after the date hereof, the Company files a
Registration Statement under the Securities Act with respect to any offering of
any equity securities by the Company for its own account or for the account of
any of its equity holders (other than (i) a registration on Form S-4 or Form S-8
or a shelf registration on Form S-3 for the sale of securities by the Company or
any successor form to such Forms or (ii) any registration of securities as it
relates to an offering and sale to management of the Company pursuant to any
employee stock plan or other employee benefit plan arrangement) then, as soon as
practicable (but in no event less than ten (10) days prior to the proposed date
of filing such Registration Statement), the Company shall give written notice of
such proposed filing to the holder of the Registrable Securities, and such
notice shall offer the holder of the Registrable Securities the opportunity to
register such number of Registrable Securities as such holder may request (a
"Piggyback Registration") and shall specify whether the offering is to be
underwritten or is to be offered on another basis. Subject to paragraph
11(b)(2), the Company shall include in such Registration Statement all
Registrable Securities requested within thirty (30) days after the receipt of
any such notice (which request shall specify the Registrable Securities intended
to be disposed of by such holder)

                                       9
<PAGE>

to be included in the Registration for such offering pursuant to a Piggyback
Registration; provided, however, that if, at any time after giving written
notice of its intention to register any securities and prior to the effective
date of the Registration Statement filed in connection with such Registration,
the Company shall determine for any reason not to register or to delay
registration of such securities, the Company may, at its election, give written
notice of such determination to such holder of Registrable Securities and,
thereupon, (i) in the case of a determination not to register, shall be relieved
of its obligation to register any Registrable Securities in connection with such
Registration (but not from its obligation to pay the Registration Expenses in
connection therewith), and (ii) in the case of a determination to delay
registering, shall be permitted to delay registering any Registrable Securities,
for the same period as the delay in registering such other securities. If the
offering pursuant to such Registration Statement is to be underwritten, then the
holder making a request for a Piggyback Registration pursuant to this paragraph
11(b)(1) must participate in such underwritten offering and shall not be
permitted to make any other offering in connection with such Registration. If
the offering pursuant to such Registration Statement is to be on any other
basis, then the holder making a request for a Piggyback Registration pursuant to
this paragraph 11(b)(1) must participate in such offering on such basis and
shall not be permitted to make an underwritten offering in connection with such
Registration. The holder of Registrable Securities shall be permitted to
withdraw all or part of such holder's Registrable Securities from a Piggyback
Registration at any time prior to the effective date thereof.

          (2)  Underwriter's Cutback.  The Company shall use its best efforts to
cause the managing underwriter or underwriters of a proposed underwritten
offering to permit the Registrable Securities requested to be included in the
Registration for such offering under paragraph 11(b)(1) or pursuant to other
piggyback registration rights granted by the Company, if any ("Piggyback
Securities"), to be included on the same terms and conditions as any similar
securities included therein.  Notwithstanding the foregoing, if the managing
underwriter or underwriters of any such proposed underwritten offerings informs
the Company and the holders of such Registrable Securities in writing that the
total amount or kind of securities, including Piggyback Securities, which such
holders and any other persons or entities intend to include in such offering
would be reasonably likely to adversely affect the price or distribution of the
securities offered in such offering or the timing thereof, then the securities
to be included in such Registration shall be (i) first, 100% of the securities
that the Company or the holder or holders making a request for a demand
registration pursuant to demand registration rights, as the case may be,
proposes to sell, and (ii) second, the number of securities that, in the opinion
of such underwriter or underwriters, can be sold without an adverse effect on
the price, timing or distribution of the securities to be included, selected pro
rata among holders of Registrable Securities and holders of other securities
subject to other piggyback registration rights granted by the Company, if any
("Piggyback Securities") to the extent any of such holders has requested
pursuant to paragraph 11(b)(1) or pursuant to other incidental registration
rights to be included in such Piggyback Registration, based on the number of
shares of Registrable Securities or Piggyback Securities requested to be
registered by each such holder.

          (c)  Hold-Back Agreements; Other Registration Rights Agreements.  Each
               ----------------------------------------------------------
holder of Registrable Securities agrees, if requested by (i) the Company or (ii)
the managing

                                       10
<PAGE>

underwriters in an underwritten offering, not to effect any public sale or
distribution of securities of the Company the same as or similar to those being
registered, or any securities convertible into or exchangeable or exercisable
for such securities, in any Registration Statement, including a sale pursuant to
Rule 144 under the Securities Act (except as part of such underwritten
registration), during the 14-day period prior to, and during the 90-day period
(or such longer period of up to 180 days as may be required by such underwriter)
beginning on, the effective date of any Registration Statement (except as part
of such registration) or the commencement of the public distribution of
securities, to the extent timely notified in writing by the Company or the
managing underwriters (or the holders, as the case may be). The Company may
enter into any other registration rights agreement.

          (d)  Holder Representations for Registration.  Each holder of
               ---------------------------------------
Registrable Securities agrees by acquisition of such Registrable Securities
that, upon receipt of any notice from the Company of the happening of any event
as a result of which a Registration Statement filed pursuant to this Agreement
or the Prospectus included in such Registration Statement (as then in effect)
contains any untrue statement of a material fact or omits to state a material
fact necessary to make the statements therein (in the case of the Prospectus and
any preliminary prospectus, in the light of the circumstances under which they
were made) not misleading or, if for any other reason it shall be necessary to
amend or supplement the Registration Statement or the Prospectus in order to
comply with the Securities Act, such holder will forthwith discontinue
disposition of Registrable Securities pursuant to such Registration Statement
until such holder's receipt of the copies of the supplemented or amended
Prospectus, or until it is advised in writing by the Company that the use of the
Prospectus may be resumed, and has received copies of any additional or
supplemental filings which are incorporated by reference in the Prospectus, and,
if so directed by the Company, such holder will deliver to the Company (at the
Company's expense) all copies, other than permanent file copies then in such
holder's possession, of the Prospectus covering such Registrable Securities
current at the time of receipt of such notice, and the Company shall, as
promptly as practicable thereafter, prepare and file with the Commission, and
furnish without charge to the selling holders and the managing underwriters, if
any, a supplement or amendment to such Registration Statement or Prospectus
which will correct such statement or omission or effect such compliance.

          (e)  Underwritten Offerings.  If the Company proposes to register any
               ----------------------
of its securities under the Securities Act as contemplated by paragraph 11(b)
and such securities are to be distributed by or through one or more
underwriters, the holders of Registrable Securities to be distributed by such
underwriters shall be parties to the underwriting agreement between the Company
and such underwriters and may, at their option, require that any or all of the
representations and warranties by, and the other agreements on the part of, the
Company to and for the benefit of such underwriters shall also be made to and
for the benefit of such holders of Registrable Securities and that any or all of
the conditions precedent to the obligations of such underwriters under such
underwriting agreement be conditions precedent to the obligations of such
holders of Registrable Securities.  Any such holder of Registrable Securities
shall not be required to make any representations or warranties to or agreements
with the Company or the underwriters other than representations, warranties or
agreements regarding such holder, such holders' Registrable Securities and such
holder's intended method of distribution or any other

                                       11
<PAGE>

representations required by law. No Person may participate in any underwritten
registration hereunder unless such Person (i) agrees to sell such Person's
securities on the basis provided in any underwriting arrangements approved by
the Persons entitled to approve such arrangements and (ii) completes and
executes all customary questionnaires, powers of attorney, indemnities,
underwriting agreements and other documents required under the terms of such
underwriting arrangements.

          (f)  Registration Expenses.  All expenses incident to the Company's
               ---------------------
performance of or compliance with the Company's registration obligations under
paragraph 11(b) will be borne by the Company, regardless of whether the
Registration Statement becomes effective; provided that the Company shall not be
responsible for fees and disbursements of counsel selected by the holders of the
Piggyback Securities being registered and underwriting discounts and commissions
and transfer taxes, if any, and fees and disbursements of counsel to such
underwriters (other than such fees and disbursements incurred in connection with
any registration or qualification of Registrable Securities under the securities
or blue sky laws of any state).  The Company will pay its internal expenses
(including, without limitation, all salaries and expenses of its officers and
employees performing legal or accounting duties), the expense of any audit and
the fees and expenses of any Person, including special experts, retained by the
Company.

          (g)  Indemnification.
               ----------------

          (1)  Indemnification by the Company.  The Company agrees to indemnify
and hold harmless, to the full extent permitted by law, each holder of
Registrable Securities, its officers, directors, employees, partners,
shareholders and agents and each Person who controls such holder (within the
meaning of the Securities Act or the Securities Exchange Act of 1934 (the
"Exchange Act")) from and against all losses, claims, damages, liabilities and
expenses (including reasonable costs of investigation and legal expenses)
arising out of or based upon any untrue or alleged untrue statement of a
material fact contained in any Registration Statement, Prospectus or preliminary
Prospectus or any omission or alleged omission to state therein a material fact
required to be stated therein or necessary to make the statements therein not
misleading, except insofar as the same are caused by or contained in any
information furnished in writing to the Company by such holder expressly for use
therein; provided, however, that the Company shall not be liable in any such
case to the extent that any such loss, claim, damage, liability or expense
arises out of or is based upon an untrue statement or alleged untrue statement
or omission or alleged omission made in any such preliminary Prospectus if (i)
it is determined that it was the responsibility of such holder to provide the
Person asserting such loss, claim, damage, liability or expense with a current
copy of the Prospectus and such holder failed to deliver or cause to be
delivered a copy of the Prospectus to such Person after the Company had
furnished such holder with a sufficient number of copies of the same and (ii)
the Prospectus completely corrected in a timely manner such untrue statement or
omission.  This indemnity shall be in addition to any liability the Company may
otherwise have, shall remain in full force and effect regardless of any
investigation made by or on behalf of such holder or any such officer, director,
employee, agent, partner, shareholder or controlling Person and shall survive
termination of this Agreement and the transfer of Registrable Securities by such
holder.  The Company will also indemnify underwriters, selling brokers, dealer
managers and similar

                                       12
<PAGE>

securities industry professionals participating in the distribution, their
officers, directors, partners, shareholders and each Person who controls such
Persons (within the meaning of the Securities Act and the Exchange Act) to the
same extent as provided above (with appropriate modification) with respect to
the indemnification of the holders of Registrable Securities, if requested.

          (2)  Indemnification by the Selling Holder of Registrable Securities.
Each selling holder of Registrable Securities, severally and not jointly, agrees
to indemnify and hold harmless, to the full extent permitted by law, the
Company, its directors and officers and each Person who controls the Company
(within the meaning of the Securities Act or the Exchange Act) from and against
any losses, claims, damages, liabilities and expenses resulting from any untrue
statement of a material fact or any omission of a material fact required to be
stated in the Registration Statement, Prospectus or preliminary Prospectus or
necessary to make the statements therein not misleading, to the extent, but only
to the extent, that such untrue statement or omission is caused by or contained
in any information furnished in writing by such selling holder to the Company
specifically for inclusion in such Registration Statement or Prospectus and has
not been corrected in a subsequent writing prior to or concurrently with the
sale of the Registrable Securities to the Person asserting such loss, claim,
damage, liability or expense.  This indemnity shall be in addition to any
liability such selling holder may otherwise have, shall remain in full force and
effect regardless of any investigation made by or on behalf of the Company or
any such officer, director or controlling Person and shall survive termination
of this Agreement and the transfer of Registrable Securities by such selling
holder.  The Company shall be entitled to receive indemnities from underwriters,
selling brokers, dealer managers and similar securities industry professionals
participating in the distribution, to the same extent as provided above (with
appropriate modification) with respect to information so furnished in writing by
such Persons specifically for inclusion in any Prospectus or Registration
Statement.

          (3)  Conduct of Indemnification Proceedings.  Any Person entitled to
indemnification hereunder will (i) give prompt written notice to the
indemnifying party of any claim with respect to which it seeks indemnification
and (ii) permit such indemnifying party to assume the defense of such claim with
counsel reasonably satisfactory to the indemnified party; provided, however,
that any delay or failure to so notify the indemnifying party shall relieve the
indemnifying party of its obligations hereunder only to the extent, if at all,
that it is prejudiced by reason of such delay or failure; provided further,
however, that any Person entitled to indemnification hereunder shall have the
right to select and employ separate counsel and to participate in the defense of
such claim, but the fees and expenses of such counsel shall be at the expense of
such Person unless (i) the indemnifying party has agreed in writing to pay such
fees or expenses, or (ii) the indemnifying party shall have failed to assume the
defense of such claim within a reasonable time after receipt of notice of such
claim from the Person entitled to indemnification hereunder and employ counsel
reasonably satisfactory to such Person, or (iii) in the reasonable judgment of
any such Person, based upon advice of its counsel, a conflict of interest may
exist between such Person and the indemnifying party with respect to such claims
(in which case, if the Person notifies the indemnifying party in writing that
such Person elects to employ separate counsel at the expense of the indemnifying
party, the indemnifying party shall not have the right to assume the defense of
such claim on behalf of such Person).  If such defense

                                       13
<PAGE>

is not assumed by the indemnifying party, the indemnifying party will not be
subject to any liability for any settlement made without its consent (but such
consent will not be unreasonably withheld), provided that an indemnifying party
shall not be required to consent to any settlement involving the imposition of
equitable remedies or involving the imposition of any material obligations on
such indemnifying party other than financial obligations for which such
indemnified party is entitled to be indemnified hereunder. No indemnifying party
shall consent to entry of any judgment or enter into any settlement which does
not include as an unconditional term thereof the giving by the claimant or
plaintiff to such indemnified party of a release from all liability in respect
to such claim or litigation. Whenever the indemnified party or the indemnifying
party receives a firm offer to settle a claim for which indemnification is
sought hereunder, it shall promptly notify the other of such offer. If the
indemnifying party refuses to accept such offer within 20 business days after
receipt of such offer (or of notice thereof), such claim shall continue to be
contested and, if such claim is within the scope of the indemnifying party's
indemnity contained herein, the indemnified party shall be indemnified pursuant
to the terms hereof. If the indemnifying party notifies the indemnified party in
writing that the indemnifying party desires to accept such offer, but the
indemnified party refuses to accept such offer within 20 business days after
receipt of such notice, the indemnified party may continue to contest such claim
and, in such event, the total maximum liability of the indemnifying party to
indemnify or otherwise reimburse the indemnified party hereunder with respect to
such claim shall be limited to and shall not exceed the amount of such offer,
plus reasonable out-of-pocket costs and expenses (including reasonable
attorneys' fees and disbursements) to the date of notice that the indemnifying
party desires to accept such offer, provided that this sentence shall not apply
to any settlement of any claim involving the imposition of equitable remedies or
to any settlement imposing any material obligations on such indemnified party
other than financial obligations for which such indemnified party is entitled to
be indemnified hereunder. An indemnifying party who is not entitled to, or
elects not to, assume the defense of a claim will not be obligated to pay the
fees and expenses of more than one counsel for all parties indemnified by such
indemnifying party with respect to such claim, unless in the written opinion of
counsel to the indemnified party reasonably satisfactory to the indemnifying
party, use of one counsel by all indemnified parties would be expected to give
rise to a conflict of interest between such indemnified parties with respect to
such claim, in which event the indemnifying party shall be obligated to pay the
fees and expenses of one such additional counsel.

          (4)  Contribution.  If for any reason the indemnification provided for
in the preceding paragraphs (a) and (b) is unavailable to an indemnified party
or insufficient to hold it harmless as contemplated by the preceding paragraphs
(a) and (b), then the indemnifying party shall contribute to the amount paid or
payable by the indemnified party as a result of such loss, claim, damage or
liability in such proportion as is appropriate to reflect not only the relative
benefits received by the indemnified party and the indemnifying party, but also
the relative fault of the indemnified party and the indemnifying party, as well
as any other relevant equitable considerations, provided that no selling holder
of Registrable Securities shall be required to contribute in an amount greater
than the dollar amount of the proceeds received by such selling holder with
respect to the sale of any such Registrable Securities.  No person guilty of
fraudulent misrepresentation (within the meaning of Section 11(f) of the
Securities Act) shall be entitled to contribution from any person who was not
guilty of such fraudulent misrepresentation.

                                       14
<PAGE>

          (h)  Assignment of Registration Rights.  The rights to cause the
               ---------------------------------
Company to register Registrable Securities pursuant to this Agreement may be
assigned by a holder to a transferee or assignee of such securities.

          (i)  No Conflicting Agreements.  The Company represents and warrants
               -------------------------
to the holder that the Company is not a party to any agreement that conflicts in
any manner with the holder's rights to cause the Company to register Registrable
Securities pursuant to any provision of this Agreement.

          (j)  Rights and Obligations Survive Exercise and Expiration of
               ---------------------------------------------------------
Warrant.  The rights and obligations of the Company and the holder set forth in
this paragraph 11 shall survive the exercise and expiration of this Warrant.

          13.  Notices.  All notices referred to in this Warrant shall be in
               -------
writing and shall be delivered personally or by certified or registered mail,
return receipt requested, postage prepaid and will be deemed to have been given
when so delivered or mailed (i) to the Company, at its principal executive
offices and (ii) to the holder of this Warrant, at such holder's address as it
appears in the records of the Company (unless otherwise indicated by such
holder).

          14.  Remedies.  The Company stipulates that the remedies at law of the
               --------
holder of this Warrant in the event of any default or threatened default by the
Company in the performance of or compliance with any of the terms of this
Warrant are not and will not be adequate, and that such terms may be
specifically enforced by a decree for the specific performance of any agreement
contained herein or by an injunction against a violation of any of the terms
hereof or otherwise.

          15.  Severability.  In the event that any one or more of the
               ------------
provisions contained herein, or the application thereof in any circumstance, is
held invalid, illegal or unenforceable, the validity, legality and
enforceability of any such provision in every other respect and of the remaining
provisions contained herein shall not be affected or impaired thereby.

          16.  Definitions.  For the purpose of this Warrant, the following
               -----------
terms shall have the following meanings:

          "Agreement" shall mean this Stock Subscription Warrant.
           ---------

          "Capital Stock" shall have the meaning assigned to such term in
           -------------
paragraph 4.

          "Consummation Date" shall mean the date of the consummation of a
           -----------------
Transaction.

          "Market Price" shall mean, on any date specified herein, (A) if any
           ------------
class of Capital Stock is listed or admitted to trading on any national
securities exchange, the highest price obtained by taking the arithmetic mean
over a period of twenty consecutive Trading Days ending the second Trading Day
prior to such date of the average, on each such Trading Day, of the high and low
sale price of shares of each such class of Capital Stock or if no such sale
takes place on such date, the

                                       15
<PAGE>

average of the highest closing bid and lowest closing asked prices thereof on
such date, in each case as officially reported on all national securities
exchanges on which each such class of Capital Stock is then listed or admitted
to trading, or (B) if no shares of any class of Capital Stock are then listed or
admitted to trading on any national securities exchange, the highest closing
price of any class of Capital Stock on such date in the over-the-counter market
as shown by Nasdaq Stock Market or, if no such shares of any class of Capital
Stock are then quoted in such system, as published by the National Quotation
Bureau, Incorporated or any similar successor organization, and in either case
as reported by any member firm of the New York Stock Exchange selected by the
Company. If no shares of any class of Capital Stock are then listed or admitted
to trading on any national securities exchange and if no closing bid and asked
prices thereof are then so quoted or published in the over-the-counter market,
"Market Price" shall mean the higher of (x) the book value per share of Capital
Stock (assuming for the purposes of this calculation the economic equivalence of
all shares of all classes of Capital Stock) as determined on a fully diluted
basis in accordance with generally accepted accounting principles by a firm of
independent public accountants of recognized standing (which may be its regular
auditors) selected by the Board of Directors of the Company as of the last day
of any month ending within 60 days preceding the date as of which the
determination is to be made or (y) the fair value per share of Capital Stock
(assuming for the purposes of this calculation the economic equivalence of all
shares of all classes of Capital Stock), as determined on a fully diluted basis
in good faith by an independent brokerage firm or Standard & Poor's Corporation
(as selected by the Board of Directors of the Company), as of a date which is 15
days preceding the date as of which the determination is to be made.

          "Person" shall mean any individual, corporation, partnership,
           ------
association, trust or other entity or organization, including a government or
political subdivision or instrumentality thereof.

          "Securities Act" shall mean the Securities Act of 1933, as amended.
           --------------

          "Trading Day" shall mean any day on which the New York Stock Exchange
           -----------
is open for trading on a regular basis.

          "Transaction" shall mean any transaction to which the Company is a
           -----------
party at any time (including, without limitation, a merger, consolidation, sale
of all or substantially all of the Company's assets, liquidation or
recapitalization of the Capital Stock) in which the previously outstanding
Capital Stock shall be changed into or exchanged for different securities of the
Company or common stock or other securities of another corporation or interests
in a noncorporate entity or other property (including cash) or any combination
of any of the foregoing or in which the Capital Stock ceases to be a publicly
traded security either listed on the New York Stock Exchange or the American
Stock Exchange or quoted by Nasdaq Stock Market or any successor thereto or
comparable system.

          "Warrant Securities" shall mean the Warrants and the Warrant Shares.
           ------------------

          17.  Miscellaneous.  This Warrant contains the entire agreement among
               -------------
the parties hereto with respect to the subject matter contained herein,
supersedes all prior agreements,

                                       16
<PAGE>

negotiations and understandings, whether written or oral, with respect to the
subject matter hereof, and any term hereof may be changed, waived, discharged or
terminated only by an instrument in writing signed by the party against which
enforcement of such change, waiver, discharge or termination is sought. This
Warrant is being delivered in the State of Illinois and shall be governed by and
construed and enforced in accordance with the internal laws of the State of
Illinois (without reference to any principles of the conflicts of laws). The
headings in this Warrant are for purposes of reference only, and shall not limit
or otherwise affect any of the terms hereof.

Dated:   July 30, 1999                            GRUBB & ELLIS COMPANY


                                                  /s/  Brian Parker
                                                  -------------------
                                                  Name:  Brian Parker
                                                  Title: EVP & CFO

Attest:

/s/  Robert J. Walner
--------------------------
Name:  Robert J. Walner
Title: Secretary

                                       17
<PAGE>

                                                                    Exhibit 4.20


                              FORM OF SUBSCRIPTION

                   (To be signed only on exercise of Warrant)

TO ______________________________

          The undersigned, the holder of the within Warrant, hereby irrevocably
elects to exercise the purchase right represented by such Warrant for, and to
purchase thereunder, ______________* shares of Common Stock of________________
_________________, and herewith makes payment of $_____________therefor [in
cash] [by cancellation of the right to buy ___ shares of Common Stock
represented by this Warrant], and requests that the certificates for such
shares be issued in the name of, and delivered to __________________________,
whose address is __________________________________________.


                                    ____________________________________
                                    (Signature must conform in all respects to
                                    name of holder as specified on the face of
                                    the Warrant)

                                    ____________________________________

                                    ____________________________________
                                                 (Address)

Dated: _____________________

_____________________________
*   Insert here the number of shares as to which the Warrant is being exercised.
<PAGE>

                                                                    Exhibit 4.20

                               FORM OF ASSIGNMENT

                   (To be signed only on transfer of Warrant)

          For value received, the undersigned hereby sells, assigns, and
transfers unto ________________________________ the right represented by the
within Warrant to purchase shares of Common Stock of________________________
_______ to which the within Warrant relates, and appoints _____________Attorney
to transfer such right on the books of ___________________________ full power of
substitution in the premises.


                                    ___________________________________
                                    (Signature must conform in all respects to
                                    name of holder as specified on the face of
                                    the Warrant)

                                    ___________________________________

                                    ___________________________________
                                                  (Address)

Dated:  ______________________