<PAGE>

EXHIBIT 10.39

                           TAX ALLOCATION AGREEMENT

    Agreement dated October 27, 1999, by and among The Ashton Technology Group,
Inc. (Parent) and its subsidiary, Universal Trading Technologies Corporation,
Inc. (UTTC).

                                  WITNESSETH

    Whereas, the parties hereto are members of an affiliated group (Affiliated
Group) as defined in Section 1504(a); and

    Whereas, such Affiliated Group will file a U.S. consolidated income tax
return for its taxable year ended March 31, 1999 and is required to file
consolidated tax returns for subsequent years; and

    Whereas, it is the intent and desire of the parties hereto that a method be
established for allocating the consolidated tax liability of the Affiliated
Group among its members, for reimbursing the Parent for payment of such tax
liability, for compensating any party for use of its losses or tax credits, and
to provide for the allocation and payment of any refund arising from a carryback
of losses or tax credits from subsequent tax years.

    Now, Therefore, in consideration of the mutual covenants and promises
contained herein, the parties hereto agree as follows:

    1.   A U.S. consolidated income tax return shall be filed by the Parent for
the tax year ended March 31, 1999, and for each subsequent taxable period in
respect of which this Agreement is in effect and for which the Affiliated Group
is required or permitted to file a consolidated tax return. UTTC shall execute
and file such consent, elections, and other documents that may be required or
appropriate for the proper filing of such returns.

    2.   For each tax period, each member of the Affiliated Group shall compute
its tax liability in accordance with the provisions of Regulation
(S) 1.1502-33(d)(3) with a fixed percentage of 100 percent and shall pay such
amount (including any increased liability allocated pursuant to such regulation
above any liability allocated pursuant to section 1552 of the Internal Revenue
Code) to the Parent. For purposes of this Agreement, any liability for
alternative minimum tax shall be treated as a tax liability subject to this
paragraph.

    3.   Payment of the consolidated tax liability for a taxable period shall
include the payment of estimated tax installments due for such taxable period,
and UTTC shall pay to the Parent its share of each payment within ten days of
receiving notice of such payment from the Parent, but in no event later than the
due date for each such payment. Any amounts paid by UTTC on account of a
separate return or separate estimated tax payments that are credited against the
consolidated tax liability of the Affiliated Group shall be included in
determining the payments due from UTTC. Any overpayment of estimated tax should
be refunded to UTTC. Any payments owed by UTTC to the Parent under this
Agreement, including payments by UTTC to the Parent of any estimated tax
installments due for each taxable period, shall be paid to the Parent, even if
the Affiliated Group as a whole does not have any consolidated estimated tax
liability for such period.

    4.   To the extent payments received in respect of a taxable year by Parent
pursuant to paragraph 2, above, exceed the consolidated tax liability for such
period as a result of the absorption or utilization of losses, deductions,
credits or similar items of UTTC against the Parent's income, gain or similar
items, then the Parent shall pay such excess amount received to UTTC in a manner
that reasonably reflects such utilization or absorption within 10 days of filing
its consolidated federal income tax return for such period.
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    5.   If part or all of an unused loss or tax credit is allocated to a member
of the Affiliated Group pursuant to Regulation (S) 1.1502-79, and is carried
back or forward to a year in which such member filed a separate return or a
consolidated return with another affiliated group, any refund or reduction in
tax liability arising from the carryback or carryover shall be retained by such
member. Notwithstanding the above, the Parent shall determine whether an
election shall be made not to carry back part or all of a consolidated net
operating loss for any tax year in accordance with Section 172(b)(3).

    6.   If the consolidated tax liability is adjusted for any taxable period,
whether by means of an amended return, claim for refund, or after a tax audit by
the Internal Revenue Service, the liability of each member shall be recomputed
to give effect to such adjustments, and in the case of a refund, the Parent
shall make payment to UTTC for its share of the refund, determined in the same
manner as in paragraphs 2 and 4 above, within ten days after the refund is
received by the Parent, and  in the case of an increase in tax liability, UTTC
shall pay to the Parent its allocable share of such increased tax liability
within ten days after receiving notice of such liability from the Parent.

    7.   If during a consolidated return period the Parent or UTTC acquires or
organizes another corporation that is required to be included in the
consolidated return, then such corporation shall join in and be bound by this
Agreement.


    8.   This Agreement shall apply to the tax year ending March 31, 1999, and
all subsequent taxable periods unless the Parent and UTTC agree to terminate the
Agreement. Notwithstanding such termination, this Agreement shall continue in
effect with respect to any payment or refunds due for all taxable periods prior
to termination.

    9.   Notwithstanding any other provisions of this Agreement, payment of any
estimated tax installment by UTTC to the Parent under this Agreement for the tax
year ending March 31, 1999 shall be made on or before October 15, 1999.

    10.  This Agreement shall be binding upon and inure to the benefit of any
successor, whether by statutory merger, acquisition of assets, or otherwise, to
any of the parties hereto, to the same extent as if the successor had been an
original party to the Agreement.

    In Witness Whereof, the parties hereto have caused this Agreement to be
executed by their duly authorized representatives on October 27, 1999.


THE ASHTON TECHNOLOGY GROUP, INC.


/s/ Arthur J. Bacci
-------------------
Arthur J. Bacci
President & Chief Financial Officer



UNIVERSAL TRADING TECHNOLOGIES CORPORATION


/s/ Fred S. Weingard
--------------------
Fred S. Weingard
President