EXHIBIT 10.20
                                                                   -------------

                  PAYMENT AND REGISTRATION RIGHTS AGREEMENT dated as of December
         28, 1999 (this "Agreement"), between EXCHANGE APPLICATIONS, INC., a
         Delaware corporation ("Exchange"), and MICROSTRATEGY INCORPORATED, a
         Delaware corporation ("MicroStrategy").

         The parties hereby agree as follows:

                                   ARTICLE I.

                          Definitions and Construction
                          ----------------------------

         Section 1.01. Certain Definitions. As used in this Agreement, the
following terms shall have the meanings specified below:

         "Business Day" shall mean any day other than a day which is a Saturday
or Sunday or any other day on which commercial banks in New York, New York are
authorized or required to remain closed.

         "Business Unit" shall have the meaning set forth in the Development
Agreement.

         "Closing" shall mean the payment of the Closing Payment on the Closing
Date.

         "Closing Date" shall mean December 28, 1999.

         "Closing Share Amount" shall mean the number of shares of Common Stock
(rounded to the nearest whole number) equal to the result obtained by dividing
(a) $20,000,000 by (b) the Fair Market Value of the Common Stock as of the
Closing Date.

         "Common Stock" shall mean the Common Stock, par value $0.001 per share,
of Exchange.

         "control" (including, with its correlative meanings, "controlled by"
and "under common control with") shall mean possession, directly or indirectly,
of power to direct or cause the direction of management or policies (whether
through ownership of securities or partnership or other ownership interests, by
contract or otherwise).

          "Designee" shall mean any wholly-owned subsidiary of MicroStrategy
designated in writing by MicroStrategy as the recipient and registered holder of
any or all of the Payment Shares to be issued under Article II.

          "Development Agreement" shall mean the Software Development and OEM
Agreement, dated as of the Closing Date, by and between MicroStrategy and
Exchange. The final form of the Development Agreement is attached hereto as
Exhibit A.
<PAGE>

         "dollars" or "$" shall mean lawful money of the United States of
America.


         "Exchange Act" shall mean the Securities Exchange Act of 1934.

         "Fair Market Value" means, as of any date of determination, the lowest
closing sale price (if listed on a stock exchange or quoted on the Nasdaq
National Market System or any successor thereto), or the lowest of the mean
between the closing bid and asked prices (if quoted on NASDAQ or otherwise
publicly traded), of the Common Stock during the period commencing on the third
trading day prior to (and including) such date and ending on the third trading
day after such date.

          "Governmental Authority" shall mean any court, administrative agency
or commission or other governmental agency or instrumentality, domestic or
foreign, or any arbitrator, of competent jurisdiction.

         "Group" shall mean a "Group" within the meaning of Section 13(d)(3) of
the Exchange Act.

          "Installment Share Amount" shall mean, with respect to any Installment
for which Exchange has elected in accordance with Section 2.02(b) to pay all or
any portion of the Payment Amount in Common Stock, the number of shares of
Common Stock (rounded to the nearest whole number) equal to the result obtained
by dividing (a) the Payment Amount to be paid on the applicable Installment Date
minus the Cash Component set forth in the applicable Stock Election Notice by
(b) the Fair Market Value of the Common Stock as of the originally scheduled
Installment Date set forth in the table contained in Section 2.01(c); provided,
however, that for purposes of this definition, in no event shall the "Fair
Market Value" as at any date be less than 75% of the Fair Market Value
determined as of the Closing Date or exceed 125% of the Fair Market Value
determined as of the Closing Date.

         "Marketing Agreement" shall mean the Joint Marketing Agreement, dated
as of the Closing Date, by and between MicroStrategy and Exchange. The final
form of the Marketing Agreement is attached hereto as Exhibit B.

         "MicroStrategy License Agreement" shall mean the License Agreement,
dated as of the Closing Date, by and between MicroStrategy and Exchange. The
final form of the MicroStrategy License Agreement is attached hereto as Exhibit
C.

         "Milestones" shall mean, at any time of determination, the milestones
for the Business Unit in effect at such time. On the Closing Date, the
Milestones shall be set forth on Exhibit A to the Development Agreement, and
thereafter, may be established or modified from time to time by the Steering
Committee.

         "Operative Agreements" shall mean this Agreement, the Development
Agreement, the Marketing Agreement, the MicroStrategy License Agreement and the
Strategy.com Agreement.

          "Payment Shares" shall mean all shares of Common Stock issued to
MicroStrategy under Article II.

                                       2
<PAGE>

         "Person" shall mean any individual, firm, corporation, partnership,
Group, trust, joint venture, Governmental Authority or other entity, and shall
include any successor (by merger or otherwise) of such entity.

         "Registration Shares" shall mean (i) all Payment Shares issued to
MicroStrategy or a Designee and (ii) all securities issued or issuable to
MicroStrategy or a Designee in respect thereof by way of stock dividend, stock
split or reclassification or in connection with a combination of shares,
recapitalization, merger or, consolidation or other reorganization or otherwise.

         "Registration Statement" shall mean, as applicable, the Shelf
Registration Statement or a registration statement filed with the SEC in
connection with a Piggyback Registration.

         "Registration Termination Date" means, with respect to any Registration
Statement, the earlier of (i) the date when all of the Registration Shares
registered thereunder shall have been sold or (ii) the third anniversary of the
Closing Date; provided however, that in the event that the right of
MicroStrategy or any Designee to use such Registration Statement (and the
prospectus relating thereto) is delayed or suspended pursuant to Section 5.07 or
5.09, Exchange shall be required to extend the Registration Termination Date
beyond the third anniversary of the Closing Date by the same number of days as
such delay or Suspension Period.

         "SEC" shall mean the Securities and Exchange Commission or any
successor commission or agency having similar powers.

         "Securities Act" shall mean the Securities Act of 1933.

         "Shelf Registration" shall mean the registration of Registration Shares
pursuant to the Shelf Registration Statement.

          "Steering Committee" shall have the meaning set forth in the
Development Agreement.

         "Strategy.com Agreement" shall mean the Strategy.com Affiliate
Agreement, dated as of the Closing Date, by and between MicroStrategy and
Exchange. The final form of the Strategy.com Agreement is attached hereto as
Exhibit D.

          "Transactions" shall mean the transactions contemplated by the
Operative Agreements.

         "Transfer" shall mean to sell, transfer or assign.

                                       3
<PAGE>

Section 1.02.     Additional Definitions.
----------------------------------------

   Defined Term                                       Section Defined in
   ------------                                       ------------------
   Accelerated Installment Date                       2.03(c)
   Closing Payment                                    2.01(a)
   Cash Component                                     2.02(b)
   Election Date                                      2.02(b)
   Extension Date                                     2.03(b)
   Installment Dates                                  2.01(c)
   Installments                                       2.01(c)
   Payment Amounts                                    2.01(c)
   Piggyback Registration                             5.02(a)
   Preferred Stock                                    3.01(c)
   Registered Sale                                    4.01
   Sale                                               4.01
   SEC Documents                                      3.01(e)
   Securities                                         3.01(c)
   Shelf Registration Statement                       5.01(a)
   Stock Election Notice                              2.02(b)
   Suspension Period                                  5.09
   Unachieved Milestones                              2.03(b)

         Section 1.03. Terms Generally. The definitions in Sections 1.01 and
1.02 shall apply equally to both the singular and plural forms of the terms
defined. Whenever the context may require, any pronoun shall include the
corresponding masculine, feminine and neuter forms. The words "include",
"includes" and "including" shall be deemed to be followed by the phrase "without
limitation". All references herein to Articles, Sections, Exhibits and Schedules
shall be deemed references to Articles and Sections of, and Exhibits and
Schedules to, this Agreement unless the context shall otherwise require. The
headings of the Articles and Sections are inserted for convenience of reference
only and are not intended to be a part of or to affect the meaning or
interpretation of this Agreement. Unless the context shall otherwise require,
any reference to any agreement or other instrument or statute or regulation are
to it as amended and supplemented from time to time (and, in the case of a
statute or regulation, to any successor provision). Any reference in this
Agreement to a "day" or a number of "days" (without the explicit qualification
of "Business") shall be interpreted as a reference to a calendar day or number
of calendar days. If any action or notice is to be taken or given on or by a
particular calendar day, and such calendar day is not a Business Day, then such
action or notice shall be deferred until, or may be taken or given on, the next
Business Day.

                                       4
<PAGE>

                                   ARTICLE II.

                         Payments and Issuance of Shares
                         -------------------------------

         Section 2.01. Payments and Issuance of Shares. In reliance upon the
representations, warranties and agreements of MicroStrategy set forth in the
Operative Agreements, and upon the terms and conditions set forth herein, in
consideration for the rights, services, interests and benefits received or to be
received by Exchange under the Development Agreement, the Marketing Agreement,
the MicroStrategy License Agreement and the Strategy.com Agreement during the
initial terms thereof:

         (a) At the Closing, Exchange shall pay MicroStrategy the sum of
$10,000,000 (the "Closing Payment").

         (b) On or before January 20, 2000, Exchange shall issue to
MicroStrategy or a Designee the number of shares of Common Stock equal to the
Closing Share Amount. Exchange shall prepare and deliver to MicroStrategy on or
prior to January 14, 2000 a certificate setting forth its calculation of the
Closing Share Amount, which certificate shall be conclusive absent manifest
error.

         (c) Subject to Section 2.03, Exchange shall pay to MicroStrategy on the
dates set forth below (the "Installment Dates") the amounts (the "Payment
Amounts") set forth opposite such dates (the "Installments"):

                  Installment Dates                           Payment Amounts
                  -----------------                           ---------------
                  June 30, 2000                               $5,833,333
                  September 1, 2000                           $5,833,333
                  December 1, 2000                            $5,833,333
                  March 1, 2001                               $5,833,333
                  June 1, 2001                                $5,833,333
                  September 1, 2001                           $5,833,335;

provided, however, that if Exchange has elected in accordance with Section
2.02(b) to pay all or any portion of the Payment Amount due on any Installment
Date in Common Stock, the relevant Installment Date shall be extended until the
tenth Business Day immediately following the date set forth above. If Exchange
has elected to pay all or any portion of any Payment Amount in Common Stock,
Exchange shall prepare and deliver to MicroStrategy on the third Business Day
prior to the Installment Date (as so extended) a certificate setting forth its
calculation of the Installment Share Amount, which certificate shall be
conclusive absent manifest error.

         (d) Payments under Section 2.01(a) or (b) are non-cancelable and, once
made, are non-refundable. Payments made under Section 2.01(c) are
non-refundable.

         Section 2.02. Payment in Common Stock; Stock Election Notice. (a) If
Exchange elects in accordance with Section 2.02(b) to pay all or any portion of
the Payment Amount for any Installment Date in Common Stock, the number of
shares of

                                       5
<PAGE>

Common Stock to be issued to MicroStrategy or a Designee on such Installment
Date shall be the Installment Share Amount determined as of the Installment
Date.

         (b) On or before the fifteenth day prior to Installment Date set forth
in the table contained in Section 2.01(c) (such fifteenth day being the
"Election Date"), Exchange may by written notice to MicroStrategy (each, a
"Stock Election Notice") elect to pay all or any portion of the Payment Amount
payable in respect of the Installment in Common Stock. Each Stock Election
Notice shall indicate the portion of the Payment Amount in respect of such
Installment to be paid in cash (the "Cash Component"), and shall be irrevocable.
If Exchange does not deliver a Stock Election Notice to MicroStrategy on or
before the Election Date for any Installment, then the entire Payment Amount
shall be paid in cash on the applicable Installment Date set forth in the table
contained in Section 2.01(c).

         Section 2.03. Termination of Installment Obligations; Extension of
Installment Dates. Anything to the contrary notwithstanding:

         (a) If either Exchange or MicroStrategy delivers a notice of
termination in accordance with Section 10.3 of the Development Agreement or
Exchange delivers a notice of termination in accordance with Section 10.1 of the
Development Agreement, the obligations of Exchange to pay any and all
Installments not yet due and payable at the time of such notice of termination
shall automatically terminate. If either Exchange or MicroStrategy terminates
the Development Agreement in accordance with Section 11.4 of the Development
Agreement, the obligations of Exchange to pay any and all Installments not yet
due and payable at the time of delivery of the written notice of default giving
rise to such termination shall automatically terminate.

         (b) If any of the Milestones for a particular Installment Date have not
been achieved by the Business Unit (the "Unachieved Milestones") on or prior to
that Installment Date with respect to any Installment payable after June 30,
2000, Exchange may elect by written notice to MicroStrategy on or before the
Installment Date to extend the applicable Installment Date until the earlier (i)
the 45th day immediately following the scheduled Installment Date contained in
the table set forth in Section 2.01(c) and (ii) the third Business Day following
the achievement of the Unachieved Milestones. If at the end of the 45 day period
described in this Section 2.03(b) (the "Extension Date"), the Business Unit has
not achieved the Milestone, then Exchange shall either (a) pay the Payment
Amount by the third Business Day following the Extension Date or (b) terminate
the Business Unit obligations pursuant to Section 10.1 of the Development
Agreement.

         (c) If the Business Unit achieves a Milestone for a particular
Installment Date prior to such Installment Date, then MicroStrategy may elect by
written notice to Exchange to accelerate the applicable Installment Date to the
20th Business Day following such notice (the "Accelerated Installment Date").
The Accelerated Installment Date shall be deemed an Installment Date for the
purposes of Section 2.02 above.

         Section 2.04. Payments; Delivery of Shares. (a) On each date on which
Exchange is obligated to make a payment of cash to MicroStrategy under this
Article

                                       6
<PAGE>

II, Exchange shall deliver to MicroStrategy the applicable sum by check or by
wire transfer to a bank account designated in writing by MicroStrategy. (b) On
each date on which Exchange is obligated to deliver shares of Common Stock to
MicroStrategy or a Designee under this Article II, Exchange shall deliver to
MicroStrategy a certificate representing the applicable number of shares of
Common Stock registered in the name of MicroStrategy or such Designee.

         Section 2.05. Designees. Each reference to MicroStrategy in Section
3.02, Article IV and Article V shall be deemed a reference to MicroStrategy and,
where applicable, each of its Designees.

                                  ARTICLE III.

                         Representations and Warranties
                         ------------------------------

         Section 3.01. Representations and Warranties of Exchange. Exchange
hereby represents and warrants to MicroStrategy on and as of the Closing Date as
follows:

         (a) Organization. Exchange is a corporation duly organized, validly
existing and in good standing under the laws of the State of Delaware and is
qualified to do business in each jurisdiction in which the character of its
properties or the nature of its business requires such qualification, except
where the failure to so qualify would not have a material adverse effect upon
Exchange.

         (b) Authorization. All corporate action on the part of Exchange, its
officers, directors and stockholders, necessary for the authorization,
execution, delivery and performance of this Agreement and the other Operative
Agreements and the consummation of the transactions contemplated herein and
therein has been taken. Each of this Agreement and the other Operative
Agreements constitute the legal, valid and binding obligation of Exchange,
enforceable against Exchange in accordance with its terms, except as such may be
limited by bankruptcy, insolvency, reorganization or other laws affecting
creditors' rights generally and by general equitable principles. Exchange has
all requisite corporate power to enter into this Agreement and the other
Operative Agreements and to carry out and perform its obligations under this
Agreement and the other Operative Agreements.

         (c) Capitalization. The authorized capital stock of Exchange consists
of (i) 30,000,000 shares of Common Stock and (ii) 10,000,000 shares of preferred
stock, par value $.001 per share (the "Preferred Stock"). The number of
outstanding shares of each class of capital stock are set forth in Schedule
3.01(c) hereto. Except as set forth in Schedule 3.01(c) hereto, there are no
existing options, warrants, calls, preemptive (or similar) rights, subscriptions
or other rights, agreements, arrangements or commitments of any character
obligating Exchange to issue, transfer or sell, or cause to be issued,
transferred or sold, any shares of capital stock of Exchange or other equity
interests in Exchange or any securities convertible into or exchangeable for
such shares of capital stock or other equity interests (collectively,

                                       7
<PAGE>

"Securities"). Schedule 3.01(c) sets forth the number of stock options
outstanding under Exchange's stock incentive plans, and the number of shares
reserved for issuance under such plans that are not subject to outstanding
options. Except as set forth in Schedule 3.01(c), no holder of any capital stock
or Securities of Exchange has any outstanding registration rights.

         (d) Valid Issuance of the Payment Share. The Payment Shares to be
issued to MicroStrategy or any Designee hereunder, upon issuance pursuant to the
terms hereof, will be duly authorized and validly issued, fully paid,
nonassessable and free of any liens or encumbrances created by Exchange and,
assuming the accuracy of the representations and warranties made by
MicroStrategy to Exchange, will be issued and sold by Exchange to MicroStrategy
or such Designee in compliance with applicable state and federal securities
laws.

         (e) SEC Documents. Exchange has furnished to MicroStrategy (or
otherwise provided access by MicroStrategy to) true and complete copies of the
documents filed by Exchange with the SEC and set forth on Schedule 3.01(e)
hereto (all such documents, collectively, the "SEC Documents"). As of their
respective filing dates, the SEC Documents complied in all material respects
with the requirements of the Exchange Act or the Securities Act, as applicable,
and none of the SEC Documents contained any untrue statement of a material fact
or omitted to state a material fact required to be stated therein or necessary
in order to make the statements made therein, in light of the circumstances
under which they were made, not misleading, as of their respective filing dates,
except to the extent corrected by a subsequently filed SEC Document.

         (f) No Conflict. The execution and delivery of this Agreement and the
other Operative Agreements by Exchange and the consummation of the transactions
contemplated hereby and thereby will not conflict with or result in any
violation of or default (with or without notice or lapse of time, or both)
under, or give rise to a right of termination, cancellation or acceleration of
any obligation or to a loss of a material benefit or give rise to an event which
results in the creation of any lien, charge or encumbrance upon any of
Exchange's properties or assets under (i) any provision of the Certificate of
Incorporation or By-laws of Exchange or (ii) any agreement or instrument,
permit, franchise, license, judgment, order, statute, law, ordinance, rule or
regulation, applicable to Exchange or its respective properties or assets,
except where any such event under clause (ii) could not reasonably be expected
to have a material adverse effect on the Transactions contemplated by this
Agreement and the other Operative Agreements.

         (g) Consents. All consents, approvals, orders, authorizations,
registrations, qualifications, and filings required on the part of Exchange to
be obtained or made prior to the Closing in connection with the execution,
delivery or performance of this Agreement and the other Operative Agreements,
and the consummation of the transactions contemplated herein and therein have
been obtained or made prior to the Closing.

                                       8
<PAGE>

         (h) Absence of Certain Changes or Events. Since the last filing date of
the SEC Documents, no event has occurred that has had a material adverse effect
on Exchange (excluding for this purpose the execution or announcement of the
transactions contemplated by this Agreement and the other Operative Agreements
and any adverse effect resulting therefrom).

         Section 3.02. Representations and Warranties of MicroStrategy.
MicroStrategy hereby represents and warrants to Exchange on and as of the
Closing Date as follows:

         (a) Organization. MicroStrategy is a corporation duly organized,
validly existing and in good standing under the laws of the State of Delaware
and is qualified to do business in each jurisdiction in which the character of
its properties or the nature of its business requires such qualification, except
where the failure to so qualify would not have a material adverse effect upon
MicroStrategy.

         (b) Authorization. All corporate action on the part of MicroStrategy,
its officers, directors and stockholders, necessary for the authorization,
execution, delivery and performance of this Agreement and the other Operative
Agreements and the consummation of the transactions contemplated herein and
therein has been taken. Each of this Agreement and the other Operative
Agreements constitute the legal, valid and binding obligation of MicroStrategy,
enforceable against MicroStrategy in accordance with its terms, except as such
may be limited by bankruptcy, insolvency, reorganization or other laws affecting
creditors' rights generally and by general equitable principles. MicroStrategy
has all requisite corporate power to enter into this Agreement and the other
Operative Agreements and to carry out and perform its obligations under this
Agreement and the other Operative Agreements.

         (c) Acquisition Solely for the Purpose of Investment. MicroStrategy is
acquiring the Payment Shares being acquired by it hereunder, for investment, for
its own account, and not for resale or with a view to distribution thereof in
violation of the Securities Act or any other applicable securities law.
MicroStrategy has no intention of participating in, and, so long as
MicroStrategy holds or has any right to acquire any Payment Shares MicroStrategy
will not participate in, the formulation, determination or direction of the
basic business decisions of Exchange within the meaning of 16 C.F.R.
801.1(i)(1).

         (d) Investor Status, etc. MicroStrategy certifies and represents to
Exchange that, at the time MicroStrategy acquires any of the Payment Shares,
MicroStrategy will be an "accredited investor" as defined in Rule 501 of
Regulation D promulgated under the Securities Act. MicroStrategy's financial
condition is such that it is able to bear the risk of holding any and all of the
Payment Shares acquired by it for an indefinite period of time and the risk of
loss of its entire investment. MicroStrategy has been afforded the opportunity
to ask questions of and receive answers from the management of Exchange
concerning Exchange and its business and this investment, and has also been
afforded the opportunity to review any relevant documents and records concerning
the business of Exchange. MicroStrategy has such

                                       9
<PAGE>

knowledge and experience in financial and business matters that it is capable of
evaluating the merits and risks of an investment in Exchange.

         (e) Payment Shares Not Registered. MicroStrategy understands that
because the Payment Shares are issued by Exchange in a transaction exempt from
the registration requirements of the Securities Act, the Payment Shares have not
been registered under the Securities Act, and that the Payment Shares must
continue to be held by MicroStrategy unless a subsequent disposition thereof is
registered under the Securities Act or is exempt from such registration.
MicroStrategy understands that the exemptions from registration afforded by Rule
144 (the provisions of which are known to it) promulgated under the Securities
Act depend on the satisfaction of various conditions, and that, if applicable,
Rule 144 may afford the basis for sales only in limited amounts.

         (f) No Conflict. The execution and delivery of this Agreement and the
other Operative Agreements by MicroStrategy and the consummation of the
transactions contemplated hereby and thereby will not conflict with or result in
any violation of or default (with or without notice or lapse of time, or both)
under, or give rise to a right of termination, cancellation or acceleration of
any obligation or to a loss of a material benefit under (i) any provision of the
Certificate of Incorporation or By-laws of MicroStrategy or (ii) any agreement
or instrument, permit, franchise, license, judgment, order, statute, law,
ordinance, rule or regulation, applicable to MicroStrategy or its respective
properties or assets, except where any such event under clause (ii) could not
reasonably be expected to have a material adverse effect on the Transactions
contemplated by this Agreement and the other Operative Agreements.

         (g) Consents. All consents, approvals, orders, authorizations,
registrations qualifications and filings required on the part of MicroStrategy
to be obtained or made prior to the Closing in connection with the execution,
delivery or performance of this Agreement and the other Operative Agreements and
the consummation of the Transactions contemplated herein or therein have been
obtained or made prior to the Closing.

         (h) Certain Acknowledgements. MicroStrategy has reviewed and
understands the SEC Documents, including the "Risk Factors" set forth therein,
and acknowledges that Exchange has made no representations or warranties to
MicroStrategy to induce MicroStrategy to enter into the Transactions, except for
those set forth herein (or, in the case of the SEC Documents, incorporated
herein by reference) and in the other Operative Agreements. MicroStrategy
acknowledges that investments in the Common Stock are risky, that the market
price of the Common Stock is volatile and subject to a variety of factors, many
of which are outside Exchange's control, and that no assurances can be or are
given by Exchange or any of its officers or directors as to the market price at
which MicroStrategy may be able to sell the Payment Shares.

                                       10
<PAGE>

                                  ARTICLE IV.

                                 Other Covenants
                                 ---------------

         Section 4.01. Restrictions on Transfer of the Payment Shares.
MicroStrategy shall not offer, sell, assign, transfer, endorse, pledge,
mortgage, hypothecate or otherwise convey or dispose of (a "Sale") any of the
Payment Shares acquired by it, or any interest therein, unless (i) any such sale
shall be effected (A) pursuant to and in conformity with an effective
registration statement under the Securities Act (a "Registered Sale"), or (B)
pursuant to and in conformity with Rule 144 under the Securities Act, and (ii)
in the case of any Sale under such Rule 144, if requested by Exchange,
MicroStategy shall have obtained and delivered to Exchange a written legal
opinion of counsel (reasonably satisfactory to Exchange as to such counsel and
as to the substance of such opinion) to the effect that any such proposed Sale
by MicroStategy does not violate the registration provisions of the Securities
Act and any applicable state securities or blue sky laws.

         Section 4.02. Effect of Violation of Transfer Restrictions; Preventive
Measures. Any Sale of any Payment Shares, or of any interest therein, in
violation of this Article IV shall be null and void. Exchange may make a
notation on its records or give instructions to any of its transfer agents in
order to implement the restrictions on transfer set forth in this Article IV.
Exchange shall not incur any liability for any delay in recognizing any transfer
of any Purchased Shares if Exchange reasonably believes that any such transfer
may have been or would be in violation of the provisions of the Securities Act,
applicable blue sky laws or this Article IV.

         Section 4.03. Legends. (a) Each certificate evidencing any of the
Payment Shares shall be endorsed with the legend set forth below, and
MicroStrategy covenants that, except to the extent such restrictions are waived
by Exchange, it shall not transfer the Payment Shares represented by any such
certificate without complying with the restrictions on transfer described in
this Agreement and the legends endorsed on such certificate:

         "THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED
         UNDER THE SECURITIES ACT OF 1933, AS AMENDED, OR THE SECURITIES LAWS OF
         ANY STATE AND MAY NOT BE OFFERED, SOLD, ASSIGNED, TRANSFERRED,
         ENDORSED, PLEDGED, MORTGAGED, HYPOTHECATED OR OTHERWISE CONVEYED OR
         DISPOSED OF, UNLESS SUCH SHARES ARE (1) SO REGISTERED OR (2) AN
         EXEMPTION FROM SUCH REGISTRATION IS AVAILABLE AND, IF REQUESTED BY
         EXCHANGE APPLICATIONS, INC. (THE "COMPANY"), A WRITTEN LEGAL OPINION OF
         COUNSEL REASONABLY SATISFACTORY TO THE COMPANY IS PROVIDED BY THE
         TRANSFEROR. IF THE SHARES REPRESENTED BY THIS CERTIFICATE ARE NOT
         TRANSFERRED PURSUANT TO AND IN CONFORMITY WITH AN EFFECTIVE
         REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 OR IN
         ACCORDANCE WITH RULE 144 OF THE SECURITIES

                                       11
<PAGE>

         ACT OF 1933, SUCH SHARES ARE ALSO SUBJECT TO CERTAIN RESTRICTIONS ON
         TRANSFER SET FORTH IN ARTICLE IV OF A PAYMENT AND REGISTRATION RIGHTS
         AGREEMENT DATED AS OF DECEMBER 28, 1999, AND NO TRANSFER OF SUCH SHARES
         SHALL BE VALID OR EFFECTIVE IF IT IS NOT EFFECTED IN COMPLIANCE WITH
         ALL OF SUCH RESTRICTIONS ON TRANSFER. A COPY OF SUCH PAYMENT AND
         REGISTRATION RIGHTS AGREEMENT MAY BE OBTAINED AT NO COST BY WRITTEN
         REQUEST MADE BY THE HOLDER OF RECORD OF SUCH SHARES TO THE SECRETARY OF
         THE COMPANY. "

         (b) Each certificate evidencing any of the Payment Shares shall be
endorsed with any legend required under any applicable state securities or blue
sky laws.

                                   ARTICLE V.

                               Registration Rights
                               -------------------

         Section 5.01. Shelf Registration. (a) As soon as possible and, in any
event, on or prior to January 31, 2000, Exchange will prepare and file with the
SEC a registration statement on Form S-3 (or Form S-1 if registration on Form
S-3 is not available to Exchange at such time) for the purpose of registering
under the Securities Act all of the Registration Shares for resale by, and for
the account of, MicroStrategy as selling stockholder thereunder (the "Shelf
Registration Statement"); provided, however, that Exchange may extend the period
to file the Shelf Registration Statement for not more than an additional 60 days
if (i) such delay would relieve Exchange of the obligation to include any
interim financial statements in the Registration Statement or (ii) Exchange
would be required to disclose in the Registration Statement any material
nonpublic information and Exchange concludes that the disclosure of such
information would be inadvisable at that time. The Shelf Registration Statement
shall permit MicroStrategy to offer and sell, on a delayed or continuous basis
pursuant to Rule 415 under the Securities Act, any or all of the Registration
Shares for the periods set forth herein.

         (b) The initial number of Registration Shares to be registered under
the Shelf Registration Statement shall equal 50% of the Closing Share Amount.
Exchange agrees to prepare and file such amendments and supplements to the Shelf
Registration Statement to increase the number of Registration Shares eligible to
be sold thereunder by an amount equal to the balance of the Closing Share Amount
on or before May 1, 2000. Exchange also agrees to prepare and file such
amendments and supplements to the Shelf Registration Statement as may be
necessary so that at any time after May 1, 2000 the Shelf Registration Statement
will cover the Payment Shares already issued to MicroStrategy (unless such
shares have been sold under the Shelf Registration Statement or sold in
connection with a Piggyback Registration) and the Installment Share Amount for
the next Installment (assuming that such

                                       12
<PAGE>

Installment will be paid entirely in Common Stock and that the Fair Market Value
on such Installment Date will equal 75% of the Fair Market Value calculated as
of the Closing Date).

         (c) Sales of the Registrable Shares pursuant to the Shelf Registration
Statement shall not be underwritten.

         Section 5.02. Piggyback Registrations. (a) If Exchange proposes to
register any Common Stock under the Securities Act for sale for cash in an
underwritten offering, Exchange shall give MicroStrategy notice of such proposed
registration (a "Piggyback Registration") at least 30 days prior to the filing
of the registration statement. At the written request of MicroStrategy delivered
to Exchange within 10 days after the receipt of the notice from Exchange, which
request shall state the number of Registration Shares that MicroStrategy wishes
to sell under the registration statement proposed to be filed by Exchange,
Exchange will use reasonable efforts to include in such underwritten
registration the Registration Shares requested to be included by MicroStrategy.

         (b) If the managing underwriters of a Piggyback Registration advise
Exchange in writing that in their opinion the number of securities requested to
be included in the registration exceeds the number which can be sold in the
offering, Exchange may exclude from the registration any or all Registration
Shares that MicroStrategy proposes to sell; provided, however, that no
Registration Shares may be excluded if the registration includes Common Stock of
holders other than MicroStrategy unless MicroStrategy is permitted to
participate in such registration with such holders on a pro rata basis.

         (c) All necessary amendments to the Shelf Registration Statement will
be made to reduce the number of shares to be sold by MicroStrategy thereunder,
in the event that shares are sold by MicroStrategy in a Piggyback Registration.

         Section 5.03. Indemnification by Exchange. In the event of any
registration of any Registration Shares of MicroStrategy under the Securities
Act, Exchange shall, and hereby does, indemnify and hold harmless MicroStrategy,
its directors and officers, each other Person who participates as an underwriter
in the offering or sale of such Registration Shares and each other Person, if
any, who controls such party or any such underwriter within the meaning of
Section 15 of the Securities Act against any losses, claims, damages or
liabilities, joint or several, to which such party or any such director or
officer or underwriter or controlling Person may become subject under the
Securities Act or otherwise, insofar as such losses, claims, damages or
liabilities (or actions or proceedings, whether commenced or threatened, in
respect thereof) arise out of or are based upon any untrue statement or alleged
untrue statement of any material fact contained in any registration statement
under which the Registration Shares were registered under the Securities Act,
any preliminary prospectus, final prospectus or summary prospectus contained
therein, or any amendment or supplement thereto, or any omission or alleged
omission to state therein a material fact required to be stated therein or
necessary to make the statements therein in light of the circumstances in which
they were made not misleading, and Exchange shall

                                       13
<PAGE>

reimburse such party and each such director, officer, underwriter and
controlling Person for any legal or any other expenses reasonably incurred by
them in connection with investigating or defending any such loss, claim,
liability, action or proceeding; provided, however, that Exchange shall not be
liable in any such case to the extent that any such loss, claim, damage,
liability (or action or proceeding in respect thereof) or expense arises out of
or is based upon an untrue statement or alleged untrue statement or omission or
alleged omission made in such registration statement, preliminary prospectus,
final prospectus, summary prospectus, amendment or supplement in reliance upon
and in conformity with written information about such party as a stockholder of
Exchange furnished to Exchange through an instrument duly executed by such party
specifically stating it is for use in the preparation thereof. Such indemnity
shall remain in full force and affect regardless of any investigation made by or
on behalf of such party or any such director, officer, controlling Person or
underwriter and shall survive any transfer of the Registration Shares.

         Section 5.04. Indemnification by MicroStrategy. Exchange may require,
as a condition to including any Registration Shares of MicroStrategy in any
registration statement filed pursuant to Section 5.01 or 5.02, that Exchange
shall have received an undertaking satisfactory to it from MicroStrategy to
indemnify and hold harmless (in the same manner and to the same extent as set
forth in Section 5.03) Exchange, each director of Exchange, each officer of
Exchange signing such Registration Statement, each Person who participates as an
underwriter in the offering or sale of such Registration Shares and each other
Person, if any, who controls Exchange or any such underwriter within the meaning
of Section 15 of the Securities Act with respect to any untrue statement or
alleged untrue statement in or omission or alleged omission from such
registration statement, any preliminary prospectus, final prospectus or summary
prospectus contained therein or any amendment or supplement thereto, if such
untrue statement or alleged untrue statement or omission or alleged omission was
made in reliance upon and in conformity with written information about
MicroStrategy furnished to Exchange through an instrument duly executed by
MicroStrategy specifically stating that it is for use in the preparation of such
registration statement, preliminary prospectus, final prospectus, summary
prospectus, amendment or supplement; provided, however, that the liabilities of
MicroStrategy hereunder shall be limited to an amount equal the net proceeds to
MicroStrategy and its permitted assignees from the Registration Shares sold in
connection with any such registration statement. Such indemnity shall remain in
full force and effect, regardless of any investigation made by or an behalf of
Exchange or any such director, officer or controlling Person and shall survive
the Transfer by MicroStrategy of the Registration Shares being registered.

         Section 5.05. Notices of Claims, etc. Promptly after receipt by an
indemnified party of notice of the commencement of any action or proceeding
involving a claim referred to in Section 5.03 or 5.04, such indemnified party
will, if a claim in respect thereof is to be made against an indemnifying party,
give notice to the latter of the commencement of such action; provided, however,
that the failure of any indemnified party to give notice as provided herein
shall not relieve the indemnifying party of its obligations under Section 5.03
or 5.04, except to the extent that the indemnifying party is actually prejudiced
by such failure to give notice. In case any such action is

                                       14
<PAGE>

brought against an indemnified party, unless in such indemnified party's
reasonable judgment a conflict of interest between such indemnified and
indemnifying parties may exist or the indemnified party may have defenses not
available to the indemnifying party in respect of such claim, the indemnifying
party shall be entitled to participate in and to assume the defense thereof,
with counsel reasonably satisfactory to such indemnified party, and after notice
from the indemnifying party to such indemnified party of its election so to
assume the defense thereof, the indemnifying party shall not be liable to such
indemnified party for any legal or other expenses subsequently incurred by the
latter in connection with the defense thereof other than reasonable costs of
investigation. No indemnifying party shall be liable for any settlement of any
action or proceeding effected without its written consent. No indemnifying party
shall, without the consent of the indemnified party, 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.

         Section 5.06. Indemnification Payments. The indemnification required by
this Article shall be made by periodic payments of the amount thereof during the
course of the investigation or defense, as and when bills are received or
expense, loss, damage or liability is incurred.

         Section 5.07. Registration Covenants of Exchange. In the event that any
Registration Shares are to be registered pursuant to Section 5.01 or 5.02,
Exchange covenants and agrees that it shall use its best efforts to effect the
registration and cooperate in the sale of the Registration Shares to be
registered and shall as expeditiously as possible:

                  (i) notify MicroStrategy, promptly after Exchange shall
receive notice thereof, of the time when the Registration Statement becomes
effective or when any amendment or supplement or any prospectus forming a part
of the Registration Statement has been filed;

                  (ii) notify MicroStrategy promptly of any request by the SEC
for the amending or supplementing of the Registration Statement or prospectus or
for additional information;

                  (iii) (A) advise MicroStrategy after Exchange shall receive
notice or otherwise obtain knowledge of the issuance of any order by the SEC
suspending the effectiveness of the Registration Statement or any thereto or of
the initiation or threatening of any proceeding for that purpose and (B)
promptly use reasonable efforts to prevent the issuance of any stop order or to
obtain its withdrawal promptly if a stop order should be issued;

                  (iv) (A) prepare and file with the SEC such amendments and
supplements to the Registration Statement and the prospectus forming a part
thereof as may be necessary to keep the Registration Statement effective until
the Registration Termination Date and (B) comply with the provisions of the
Securities Act with respect to the disposition of all Registration Shares
covered by the

                                       15
<PAGE>

Registration Statement in accordance with the intended methods of disposition by
MicroStrategy set forth in the Registration Statement;

                  (v) furnish to MicroStrategy such number of copies of the
Registration Statement, each amendment and supplement thereto, the prospectus
included in the Registration Statement (including any preliminary prospectus)
and such other documents as MicroStrategy may reasonably request in order to
facilitate the disposition of the Registration Shares owned by MicroStrategy;

                  (vi) notify MicroStrategy, at any time when a prospectus
relating thereto is required to be delivered under the Securities Act, of the
happening of any event as a result of which the Registration Statement would
contain an untrue statement of a material fact or omit to state any material
fact required to be stated therein or necessary to make the statements therein
not misleading, and, at the request of MicroStrategy, prepare a supplement or
amendment to the Registration Statement so that the Registration Statement shall
not, to Exchange's knowledge, contain an untrue statement of a material fact or
omit to state any material fact required to be stated therein or necessary to
make the statements therein not misleading, provided that upon such notification
by Exchange, MicroStrategy will not offer or sell Registration Shares until
Exchange has notified MicroStrategy that it has prepared a supplement or
amendment to such prospectus and delivered copies of such supplement or
amendment to MicroStrategy;

                  (vii) if the Registration Shares are securities of a class
then listed on a securities exchange or traded through a self-regulatory
organization, cause the Registration Shares to be so listed or traded;

                  (viii) provide a transfer agent and registrar, which may be a
single entity, for all the Registration Shares not later than the effective date
of the Registration Statement;

                  (ix) use its best efforts to cause the Registration Shares
covered by the Registration Statement to be registered with or approved by such
other Governmental Authorities as may be necessary to enable MicroStrategy to
consummate the disposition of such Registration Shares; and

                  (x) otherwise use its best efforts to comply with all
applicable rules and regulations of the SEC and timely file all reports required
to be filed by it under the Exchange Act, and the rules and regulations adopted
by the SEC thereunder, all to the extent required to enable MicroStrategy to
sell its Payment Shares pursuant to Rule 144 and the Registration Statement.

                  Section 5.08. Expenses. Exchange shall pay, on behalf of
MicroStrategy, all the expenses in connection with the Shelf Registration or any
Piggyback Registration, including all registration, filing and regulatory review
fees, all fees and expenses of complying with securities or blue sky laws, all
listing fees, all word processing, duplicating and printing expenses, all
messenger and delivery expenses, the fees and disbursements of counsel for
Exchange and of its independent public accountants (including the expenses of
comfort letters required by or incident to such performance

                                       16
<PAGE>

and compliance), and any fees and disbursements of underwriters customarily paid
by issuers or sellers of securities, but excluding any underwriting discounts
and commissions and transfer taxes, if any, on the Registration Shares. In any
registration, MicroStrategy shall pay for its own underwriting discounts and
commissions and transfer taxes, and its own legal fees.

         Section 5.09. Deferral. Notwithstanding anything in this Agreement to
the contrary, if Exchange shall furnish to MicroStrategy a certificate signed by
the President or Chief Financial Officer of Exchange stating that the Board of
Directors of Exchange has made the good faith determination (i) that continued
use by MicroStrategy of a Registration Statement for purposes of effecting
offers or sales of Registration Shares pursuant thereto would require, under the
Securities Act, premature disclosure in the Registration Statement (or the
prospectus relating thereto) of material, nonpublic information concerning
Exchange, its business or prospects or any proposed material transaction
involving Exchange, (ii) that such premature disclosure would be materially
adverse to Exchange, its business or prospects or any such proposed material
transaction significantly less likely and (iii) that it is therefore advisable
to suspend the use by MicroStrategy of such Registration Statement (and the
prospectus relating thereto) for purposes of effecting offers or sales of
Registration Shares pursuant thereto, then the right of MicroStrategy to use the
Registration Statement (and the prospectus relating thereto) for purposes of
effecting offers or sales of Registration Shares pursuant thereto shall be
suspended for a period (the "Suspension Period") of not more than 60 days after
delivery by Exchange of the certificate referred to above in this Section 5.09.
During the Suspension Period, MicroStrategy shall not offer or sell any
Registration Shares pursuant to or in reliance upon the Registration Statement
(or the prospectus relating thereto). Notwithstanding the foregoing, Exchange
shall not be entitled to Suspension Periods totaling more than 90 days in any
consecutive twelve-month period during the term of this Agreement.

         Section 5.10. Assignment of Registration Rights. The registration
rights set forth in this Article V may not be assigned to any Person, other than
an affiliate of MicroStrategy.

                                  ARTICLE VI.

                                  Miscellaneous
                                  -------------

         Section 6.01. Notices. Except as expressly provided herein, notices and
other communications provided for herein shall be in writing and shall be
delivered by hand or overnight courier service, mailed or sent by telecopier, as
follows:

                                       17
<PAGE>

         (a)      if to Exchange,

                  Exchange Applications, Inc.
                  89 South Street
                  Boston, Massachusetts 02111
                  Telephone:  (617) 737-2244
                  Telecopier:  (617) 790-2849
                  Attention:  Andrew J. Frawley and Wayne Townsend

         (b)      if to MicroStrategy,

                  MicroStrategy Incorporated
                  8000 Towers Crescent Drive
                  Vienna, Virginia  22182
                  Telephone:  (703) 848-8657
                  Telecopier:  (703) 848-8748
                  Attention:  Adam J. Ruttenberg

or to such other address or attention of such other person as any party shall
advise the other party in writing. All notices and other communications given to
a party hereto in accordance with the provisions of this Agreement shall be
deemed to have been given on the date of receipt.

         Section 6.02. APPLICABLE LAW; WAIVER OF JURY TRIALS. THE VALIDITY,
CONSTRUCTION AND PERFORMANCE OF THIS AGREEMENT SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE COMMONWEALTH OF MASSACHUSETTS,
APPLICABLE TO CONTRACTS EXECUTED IN AND PERFORMED ENTIRELY WITHIN SUCH
COMMONWEALTH, WITHOUT REFERENCE TO ANY CHOICE OF LAW PRINCIPLES OF SUCH
COMMONWEALTH. WITH RESPECT TO ANY LEGAL PROCEEDING ARISING OUT OF THIS
AGREEMENT, ANY OF THE OTHER OPERATIVE AGREEMENTS OR ANY TRANSACTION, THE PARTIES
EXPRESSLY WAIVE ANY RIGHT THEY MAY HAVE TO A JURY TRIAL AND AGREE THAT ANY SUCH
LEGAL PROCEEDING SHALL BE TRIED BY A JUDGE WITHOUT A JURY.

         Section 6.03. Severability. If any provision of this Agreement shall be
hold to be illegal, invalid or unenforceable, that provision will be enforced to
the maximum extent permissible so as to effect the intent of the parties, and
the validity, legality and enforceability of the remaining provisions shall not
in any way be affected or impaired thereby. If necessary to effect the intent of
the parties, the parties will negotiate in good faith to amend this Agreement to
replace the unenforceable language with enforceable language which as closely as
possible reflects such intent.

         Section 6.04. Amendments. This Agreement may be modified or waived only
by a written a persons authorized to so bind each party.

         Section 6.05. Waiver. The waiver by any party of any instance of the
other party's noncompliance with any obligation or responsibility herein shall
not be deemed a waiver of other instances or of any party's remedies for such
noncompliance.

         Section 6.06. Counterparts. This Agreement may be executed in one or
more counterparts (including by telecopier), all of which shall be considered
one and the

                                       18
<PAGE>

same agreement, and shall become effective when one or more counterparts shall
have been signed by each party and delivered to each other party.

         Section 6.07. Entire Agreement. The provisions of this Agreement, and
the other Operative Agreements set forth the entire agreement and understanding
among the parties as to the subject matter hereof and supersede all prior
agreements, oral or written, and all other communications between the parties
relating to the subject matter hereof.

         Section 6.08. Assignment. (a) Except as expressly set forth in this
Agreement, no party shall assign this Agreement or any of its rights or
obligations hereunder without the prior written consent of the other parties,
provided, that no such consent shall be required for a transfer by operation of
law in connection with a merger or consolidation of such party (without
prejudice to any other rights the parties may have under any other Operative
Agreement).

         (b) Any attempted assignment of this Agreement in violation of this
Section shall be void and of no effect.

         (c) This Agreement shall be binding upon, inure to the benefit of and
be enforceable by the parties hereto and their respective successors and
permitted assigns.

         Section 6.09. Survival of Agreement. All covenants, agreements,
represent-ations and warranties made by any party herein and in the certificates
or other instruments prepared or delivered in connection with or pursuant to
this Agreement shall be considered to have been relied upon by the other parties
and shall survive the Closing, regardless of any investigation made by the other
parties hereto or on their behalf.

         Section 6.10. No Third-Party Beneficiaries. This Agreement is for the
sole benefit of the parties and their permitted assigns and nothing herein
expressed or implied shall give or be construed to give to any Person, other
than the parties and such assigns, any legal or equitable rights hereunder,
except that Sections 5.03 and 5.04 and are intended to be for the benefit of the
Persons named therein

         Section 6.11. Expenses. (a) All costs and expenses incurred in
connection with the Operative Agreements and the Transactions shall be paid by
the party incurring such cost or expense, except as the parties shall otherwise
agree.

         (b) The provisions of this Section shall remain operative and in full
force and effect regardless of the expiration of this Agreement or the
consummation of the Transactions.

         Section 6.12. Remedies. In no event will any party be liable to another
party for incidental damages, lost profits, lost savings, or any other
consequential damages, even if such party has been advised of the possibility of
such damages, resulting from the breach of its obligations under any Operative
Agreement or from the use of any confidential or other information.

                                       19
<PAGE>

         Section 6.13. Publicity. No public release, announcement or other form
of publicity concerning the Transactions shall be issued by any party without
the prior consent of the other party, except as such release or announcement may
be required by law or the rules or regulations of any securities exchange, in
which case the party required to make the release or shall, to the extent
possible, allow the other party reasonable time to comment on such release or
announcement in advance of such issuance.SECTION 2.04

         Section 6.14. Construction. This Agreement has been negotiated by the
parties and their respective counsel and will be fairly interpreted in
accordance with its terms and without any strict construction in favor of or
against any party.

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

                                         EXCHANGE APPLICATIONS, INC.


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

                                         MICROSTRATEGY INCORPORATED


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