EXHIBIT 10.23


                        THE ASHTON TECHNOLOGY GROUP, INC.

                                 PROMISSORY NOTE

$300,000                                                          April 30, 2002

          FOR VALUE RECEIVED, the undersigned, THE ASHTON TECHNOLOGY GROUP,
INC., a Delaware corporation (the "Company"), and each of the Subsidiaries
(together with the Company, the "Borrowers" and each, a "Borrower"), jointly and
severally, hereby promises to pay to OPTIMARK INNOVATIONS INC., a Delaware
corporation, or its assigns (the "Payee"), the principal sum of THREE HUNDRED
THOUSAND DOLLARS ($300,000), or such lesser principal amount as shall then equal
the outstanding principal amount thereof, plus interest.

          1. Interest Rate. Interest on the outstanding principal balance of
this Note shall accrue at the rate of ten percent (10%) per annum, computed on
the basis of a 360-day year for the actual number of days elapsed. Interest
shall be compounded every ninety (90) days from the date hereof and shall accrue
from the date hereof until all amounts arising under this Note are paid in full.
Upon the occurrence and during the continuance of an Event of Default (as
defined in Section 10 of this Note), interest on the outstanding principal
balance of this Note shall accrue at the Default Rate (as defined in Section 12
of this Note).

          2. Payment of Principal and Interest. The outstanding principal
balance of this Note, together with all accrued but unpaid interest, shall be
due and payable on the earlier to occur of (i) the date of the closing (the
"Closing") of the transactions contemplated by that certain Securities Purchase
Agreement, dated as of February 4, 2002 (as amended on March 6, 2002, the
"Securities Purchase Agreement") by and between the Company and the Payee, or
(ii) May [10], 2002 (the "Maturity Date"). The principal, interest and other
sums due on this Note shall be reflected by the Payee's records which will be
prima facie evidence of the computation of the amounts owing by the Company to
the Payee, absent manifest error. Payment of both principal and interest on this
Note shall be in such coin or currency of the United States of America as at the
time of payment shall be legal tender for the payment of public and private
debts and shall be payable at the principal office of the Payee or at such other
address designated in writing by the Payee to the Company, as designated agent
of the Borrowers.

          3. Pre-Payment. The Borrowers may prepay, without penalty or premium,
all or any portion of the unpaid principal amount of this Note, together with
accrued interest on the amount prepaid.

          4. Compliance with Laws. It is expressly stipulated and agreed to by
the Borrowers and the Payee at all times that it is their intent to comply with
applicable state law or applicable United States federal law (to the extent it
permits the Payee to contract for, charge, take, reserve or receive a greater
amount of interest than under state law) and that this section shall control
every other covenant and agreement in this Note. If the applicable law (state or
federal) is ever judicially interpreted so as to render usurious any amount
called for under this

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Note, or contracted for, charged, taken, reserved or received with respect to
the indebtedness evidenced by this Note, then it is each Borrower's and the
Payee's express intent that all excess amounts theretofore collected by the
Payee be credited on the principal balance of this Note (or, if this Note has
been or would thereby be paid in full, refunded to the Company, as agent of the
Borrowers), and the provisions of this Note immediately be deemed reformed and
the amounts thereafter collectible hereunder and thereunder reduced, without the
necessity of the execution of any new document, so as to comply with the
applicable law, but so as to permit the recovery of the fullest amount otherwise
called for hereunder and thereunder.

          5. Waiver of Presentment, etc. Each Borrower and all endorsers of this
Note hereby waive presentment, demand, protest and notice. The Payee shall,
promptly upon full payment by the Borrowers of the principal of and interest on
this Note, together with all costs and expenses, if any, due hereon, surrender
this Note to the Company, as agent for the Borrowers, for retirement and
cancellation; provided, however, that to the extent the Borrowers make a payment
or payments to the Payee, which payment or payments or any part thereof are
subsequently invalidated, declared to be fraudulent or preferential, set aside,
and/or required to be repaid to a trustee, receiver, or any other party under
the United States Bankruptcy Code, as amended, any state or federal law, common
law, or equitable causes (a "Voidable Transfer") and the Payee is required to
repay or restore any such Voidable Transfer or the amount or any portion
thereof, or upon the advice of its counsel is advised to do so, then as to any
such Voidable Transfer or the amount repaid or restored (including all
reasonable costs, expenses and attorneys' fees of the Payee related thereto),
the joint and several liability of the Borrowers shall automatically be revived,
reinstated and restored and shall exist in full force and effect as though such
Voidable Transfer had never been made.

          6. Collection Costs. Should the indebtedness evidenced by this Note or
any part thereof be collected in any proceeding at law, or this Note be placed
in the hands of attorneys for collection after default by the Borrowers, jointly
and severally, in making due and punctual payment of principal at maturity and
interest hereunder, the Borrowers, jointly and severally, agree to pay all costs
of collecting this Note, including reasonable attorneys' fees and expenses and
court costs, if any.

          7. Protective Covenants. For so long as any amounts remain outstanding
under this Note, the prior approval of the Payee shall be required for the
Company to:

               (a) authorize or issue any equity security, other than shares of
Common Stock underlying options granted and outstanding as of the date of this
Note;

               (b) increase the aggregate authorized number of shares of Common
Stock or any other class or series of capital stock of the Company;

               (c) enter into any agreement with any holder of any securities of
the Company or any Subsidiary giving such holder the right to require the
Company or such Subsidiary to initiate any registration of the Company's or such
Subsidiary's securities under the Securities Act of 1933, as amended;

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               (d) repurchase or redeem any of the Company's or any Subsidiary's
securities;

               (e) (i) merge, combine or consolidate with, or agree to merge,
combine or consolidate with, or purchase, or agree to purchase, all or
substantially all of the securities of, any Person or (ii) purchase, or agree to
purchase, all or substantially all of the assets and properties of, or otherwise
acquire, or agree to acquire, all or any portion of, any Person;

               (f) sell all or substantially all of the Company's or any
Subsidiary's assets;

               (g) alter or change materially or adversely, the rights of the
Common Stock or any other class or series of capital stock of the Company;

               (h) make any capital expenditures in excess of $25,000 in any
fiscal year;

               (i) incur debt or guarantees (other than trade payables incurred
by the Company in the ordinary course of business) in excess of $25,000;

               (j) make any loan or advance, other than travel advances to
employees in the ordinary course of business;

               (k) adopt any employee benefit, bonus or stock plan;

               (l) engage in any transaction with any Affiliate or officer,
director or stockholder (or their relatives), other than in the ordinary course
of business and at arms-length;

               (m) amend or propose to amend the Company's certificate of
incorporation or by-laws;

               (n) liquidate or dissolve, effect any recapitalization or
reorganization, or any stock split, reverse stock split, or, in each case,
obligate the Company or its Subsidiaries to do so;

               (o) declare or pay any dividend or make any other distribution to
its stockholders in respect of any shares of its capital stock; or

               (p) engage in any other business other than that business
currently engaged in by the Company and its Subsidiaries.

          8. Assignment. Neither this Note nor the rights and obligations of any
Borrower may be assigned by such Borrower without the prior written consent of
the Payee and any attempted assignment in contravention of this Note shall be
null and void and of no effect. The Payee may assign its rights or obligations
hereunder to any Affiliate of the Payee; provided that, in the event that any
such assignment is in violation of any federal securities laws or any rules or
regulations of the NASD or would result in the delisting of the Company's
securities

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from the Nasdaq OTC Bulletin Board, such assignment shall be null and void and
of no force or effect. This Note when surrendered for assignment or transfer by
the Payee shall be accompanied by the Assignment Form attached hereto duly
executed by the Payee. Effective upon any such assignment, the Person to whom
such rights, interests and obligations were assigned shall have and exercise all
of the Payee's rights, interest and obligations hereunder as if such Person were
the original Payee of this Note.

          9. No Rights as Stockholder; Note is Debt. This Note does not entitle
the Payee hereof to any voting rights or other rights as a stockholder of any
Borrower. Each Borrower shall treat, account and report this Note as debt and
not equity for accounting and tax purposes.

          10. Event of Default. In the case of an Event of Default (as defined
below), the principal of and accrued and unpaid interest on the Note shall ipso
facto become and be immediately due and payable without any declaration or other
act on the part of any holder. For purposes hereof, "Event of Default" means the
occurrence of any of the following:

               (a) the entry of a decree or order for relief by a court having
jurisdiction in the premises in respect of any Borrower in an involuntary case
under the federal bankruptcy laws, as now constituted or hereafter amended, or
any other applicable federal or state bankruptcy, insolvency or other similar
laws, or appointing a receiver, liquidator, assignee, custodian, trustee,
sequestrator (or similar official) of any Borrower or for any substantial part
of their property, or ordering the winding-up or liquidation of any of their
affairs and the continuance of any such decree or order unstayed and in effect
for a period of 60 consecutive days;

               (b) the commencement by any Borrower of a voluntary case under
the federal bankruptcy laws, as now constituted or hereafter amended, or any
other applicable federal or state bankruptcy, insolvency or other similar laws,
or the consent by any of them to the appointment of or taking possession by a
receiver, liquidator, assignee, custodian, trustee, sequestrator (or similar
official) of any Borrower or for any substantial part of their property, or the
making by any of them of any assignment for the benefit of creditors, or the
failure by any Borrower generally to pay its debts as such debts become due, or
the taking of corporate action by any Borrower in furtherance of or which might
reasonably be expected to result in any of the foregoing; or

               (c) the breach of any representation, warranty or covenant of any
Borrower contained in the Securities Purchase Agreement.

          11. Loss, Theft or Destruction of Note. Upon receipt by the Borrowers
of evidence reasonably satisfactory to it of the loss, theft or destruction of
this Note and of indemnity or security reasonably satisfactory to it, the
Company, as designated agent of the Borrowers, will make and deliver a new Note
which shall carry the same rights to interest (unpaid and to accrue) carried by
this Note, stating that such Note is issued in replacement of this Note, making
reference to the original date of issuance of this Note (and any successors
hereto) and dated as of such cancellation, in lieu of this Note.

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          12. Definitions. As used in this Note, the following terms shall have
the following meanings:

               (a) "Affiliate" has the meaning specified in Rule 12b-2 under the
Securities Exchange Act of 1934, as amended, and the rules and regulations
promulgated thereunder.

               (b) "Borrower" and "Borrowers" have the meanings set forth in the
preamble.

               (c) "Business Day" means any day other than a Saturday, Sunday or
other day on which banks in the City of New York are required or authorized to
be closed.

               (d) "Common Stock" means the Company's common stock, par value
$.01 per share.

               (e) "Company" has the meaning set forth in the preamble.

               (f) "Default Rate" means an interest rate of fifteen percent
(15%) per annum.

               (g) "Event of Default" has the meaning set forth in Section 10.

               (h) "NASD" means the National Association of Securities Dealers,
Inc.

               (i) "Note" means this 10% Promissory Note, as may be adjusted as
provided herein.

               (j) "Payee" has the meaning set forth in the preamble.

               (k) "Person" means any natural person, firm, corporation,
propriety, public or private company, partnership, limited liability company,
public liability company, trust or other entity, and shall include any successor
(by merger or otherwise) of such entity.

               (l) "Subsidiary" and "Subsidiaries" means, individually or
collectively, (i) UTTC; (ii) NextExchange, Inc., a Delaware corporation and
wholly-owned Subsidiary of UTTC; (iii) Croix Securities, Inc., a Delaware
corporation and wholly-owned Subsidiary of UTTC; (iv) REB Securities, Inc., a
Delaware corporation and wholly-owned Subsidiary of UTTC; (v) ATG Trading, LLC,
a Delaware limited liability company and wholly owned subsidiary of the Company;
(vi) Ashton Technology Canada, Inc., a corporation subsisting under the laws of
Canada and majority owned subsidiary of the Company; and (viii) Electronic
Market Center, Inc., a Delaware corporation and majority owned subsidiary of the
Company.

               (m) "UTTC" means Universal Trading Technologies Corporation, a
Delaware corporation and Subsidiary of the Company.

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               (n) "Voidable Transfer" has the meaning set forth in Section 5.

          13. Miscellaneous.

               (a) Notices. Any notice, request or other communications required
or permitted hereunder shall be given upon personal delivery or upon the seventh
day following mailing by registered airmail (or certified first class mail if
both the addresser and addressee are located in the United States), postage
prepaid and addressed to the parties as follows:

          To the Borrowers:

                    c/o The Ashton Technology Group, Inc.
                    1835 Market Street, Suite 420
                    Philadelphia, PA  19103
                    Attn: William W. Uchimoto, General Counsel

          with a copy to:

                    Christopher S. Auguste, Esq.
                    Jenkens & Gilchrist Parker Chapin LLP
                    The Chrysler Building
                    405 Lexington Avenue
                    New York, NY  10174

          To the Payee:

                    OptiMark Innovations Inc.
                    c/o OptiMark Holdings, Inc.
                    10 Exchange Place
                    24th Floor
                    Jersey City, NJ  07302
                    Attn:  President

or to such other single place as any single addressee shall designate by written
notice to the other addressees.

               (b) Enforcement. The Borrowers shall pay all reasonable fees and
expenses, including reasonable attorney's fees, incurred by the Payee in the
enforcement in any of the Borrowers' obligations hereunder not performed when
due.

               (c) Survival of Agreement. All covenants, agreements,
representations and warranties made by any Borrower herein shall be considered
to have been relied upon by the Payee and shall survive the making of the loan
and the execution and delivery to the Payee of this Note, regardless of any
investigation made by the Payee or on its behalf; and shall continue in full
force and effect until this Note shall terminate.

               (d) Binding Effect; Several Agreement; Successors and Assigns.
This Note shall become effective as to each Borrower when executed by such
Borrower and

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delivered to the Payee, and thereafter shall be binding upon the Borrowers and
the Payee and their respective successors and permitted assigns, and shall inure
to the benefit of each and their respective successors and permitted assigns.

               (e) Governing Law. This Note shall be construed in accordance
with and governed by the laws of the State of New York without regard to its
conflicts of laws principles.

               (f) Waivers. No failure or delay of the Payee in exercising any
power or right hereunder shall operate as a waiver thereof, nor shall any single
or partial exercise of any such right or power, or any abandonment or
discontinuance of steps to enforce such a right or power, preclude any other or
further exercise thereof or the exercise of any other right or power. The rights
and remedies of the Payee hereunder are cumulative and are not exclusive of any
rights or remedies that they would otherwise have. No waiver of any provisions
of this Note or consent to any departure by any Borrower herefrom shall in any
event be effective unless the same shall be permitted by the last sentence of
this paragraph (f), and then such waiver or consent shall be effective only in
the specific instance and for the purpose for which given. No notice to or
demand on any Borrower in any case shall entitle such Borrower to any other or
further notice or demand in similar or other circumstances. Neither this Note
nor any provision hereof may be waived except pursuant to an agreement or
agreements, in writing entered into by the Borrowers and the Payee.

               (g) Severability. In the event any one or more of the provisions
contained in this Note should be held invalid, illegal or unenforceable in any
respect, the validity, legality and enforceability of the remaining provisions
contained herein shall not in any way be affected or impaired thereby (it being
understood that the invalidity of a particular provision in a particular
jurisdiction shall not in and of itself affect the validity of such provision in
any other jurisdiction). The parties shall endeavor in good-faith negotiations
to replace the invalid, illegal or unenforceable provisions with valid
provisions the economic effect of which comes as close as possible to that of
the invalid, illegal or unenforceable provisions.

                            [signature pages follow]

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          IN WITNESS WHEREOF, each Borrower has caused this Promissory Note to
be executed by its officer thereunto duly authorized.

                                        BORROWERS:

                                        COMPANY:

                                        THE ASHTON TECHNOLOGY GROUP, INC.


                                        By:/s/William W. Uchimoto
                                           ----------------------
                                        Name: William W. Uchimoto
                                        Title: EVP & General Counsel

                                        SUBSIDIARIES:

                                        UNIVERSAL TRADING TECHNOLOGIES
                                        CORPORATION


                                        By:/s/William W. Uchimoto
                                           ----------------------
                                           Name: William W. Uchimoto
                                           Title: EVP & General Counsel

                                        NEXTEXCHANGE, INC.


                                        By:/s/William W. Uchimoto
                                           ----------------------
                                           Name: William W. Uchimoto
                                           Title: EVP & General Counsel

                                        CROIX SECURITIES, INC.


                                        By:/s/ William W. Uchimoto
                                           -----------------------
                                           Name: William W. Uchimoto
                                           Title: EVP & General Counsel

                                        REB SECURITIES, INC.


                                        By:/s/William W. Uchimoto
                                           ----------------------
                                           Name: William W. Uchimoto
                                           Title: EVP & General Counsel

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                                        ATG TRADING, LLC


                                        By:/s/ William W. Uchimoto
                                           -----------------------
                                           Name: William W. Uchimoto
                                           Title: EVP & General Counsel

                                        ASHTON TECHNOLOGY CANADA, INC.


                                        By:/s/ William W. Uchimoto
                                           -----------------------
                                           Name: William W. Uchimoto
                                           Title: EVP & General Counsel

                                        ELECTRONIC MARKET CENTER, INC.


                                        By:/s/ Fredric W. Rittereiser
                                           ---------------------------------
                                           Name: Fredric W. Rittereiser
                                           Title: Director

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                                 ASSIGNMENT FORM

              (To Assign the foregoing Note, execute this form and
              supply required information.)

          FOR VALUE RECEIVED, an interest corresponding to the unpaid principal
amount of the foregoing Note and all rights evidenced thereby are hereby
assigned to

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whose address is
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Date:
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Payee's Signature:
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Payee's Address:
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Signature Guaranteed:
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NOTE:      The signature to this Assignment Form must correspond with the name
           as it appears on the face of the Note, without alteration or
           enlargement or any change whatever, and must be guaranteed by a bank
           or trust company. Officers of corporations and those acting in a
           fiduciary or other representative capacity should file proper
           evidence of authority to assign the foregoing Note.