EXHIBIT 10.24


                                 OPTIMARK, INC.

                                 PROMISSORY NOTE


$200,000                                                          April 30, 2002


       FOR VALUE RECEIVED, the undersigned, OPTIMARK, INC., a Delaware
corporation (the "Borrower"), hereby promises to pay to THE ASHTON TECHNOLOGY
GROUP, INC., a Delaware corporation, or its assigns (the "Payee"), the principal
sum of TWO HUNDRED THOUSAND DOLLARS ($200,000), 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 OptiMark Innovations Inc. (the "Investor")
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 Borrower 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
Borrower.

       3. Pre-Payment. The Borrower 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. Application of Loan Proceeds. On the Maturity Date and in lieu of
re-payment of the loan evidenced by this Note, the Payee agrees that the unpaid
principal amount of this Note, together with accrued interest thereon, shall be
credited against reimbursable expenses due and owing by the Payee to the
Investor and its Affiliates, including the Borrower, pursuant to Section 6.10 of
the Securities Purchase Agreement.

       5. Compliance with Laws. It is expressly stipulated and agreed to by the
Borrower 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,


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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 Note, or contracted for,
charged, taken, reserved or received with respect to the indebtedness evidenced
by this Note, then it is the 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 Borrower), 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.

       6. Waiver of Presentment, etc. The Borrower and all endorsers of this
Note hereby waive presentment, demand, protest and notice. The Payee shall,
promptly upon full payment by the Borrower of the principal of and interest on
this Note, together with all costs and expenses, if any, due hereon, surrender
this Note to the Borrower for retirement and cancellation; provided, however,
that to the extent the Borrower makes 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 liability of the Borrower
shall automatically be revived, reinstated and restored and shall exist in full
force and effect as though such Voidable Transfer had never been made.

       7. 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 Borrower in making
due and punctual payment of principal at maturity and interest hereunder, the
Borrower agrees to pay all costs of collecting this Note, including reasonable
attorneys' fees and expenses and court costs, if any.

       8. Assignment. Neither this Note nor the rights and obligations of the
Borrower may be assigned by the 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, 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.


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       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 the
Borrower. The 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 the 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 the 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; or

               (b) the commencement by the 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 the 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 the Borrower generally to pay its debts as such debts become due, or
the taking of corporate action by the Borrower in furtherance of or which might
reasonably be expected to result in any of the foregoing.

       11. Loss, Theft or Destruction of Note. Upon receipt by the Borrower 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 Borrower
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.

       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" has 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.


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

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

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

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

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

               (i) "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.

               (j) "Voidable Transfer" has the meaning set forth in Section 6.


       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 Borrower:

                               OptiMark, Inc.
                               10 Exchange Place
                               24th Floor
                               Jersey City, NJ  07302

                with a copy to:

                               Evan S. Seideman, Esq.
                               Cummings & Lockwood
                               Four Stamford Plaza
                               107 Elm Street
                               Stamford, CT 06904-0120

                  To the Payee:

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


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                with a copy to:

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

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

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

               (c) Survival of Agreement. All covenants, agreements,
representations and warranties made by the 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 the Borrower when executed by the
Borrower and delivered to the Payee, and thereafter shall be binding upon the
Borrower 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 the 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 the Borrower in any case shall entitle the 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 Borrower 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


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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, the Borrower has caused this Promissory Note to be
executed by its officer thereunto duly authorized.

                                             BORROWER:

                                             OPTIMARK, INC.


                                             By:/s/Robert Warshaw
                                                --------------------
                                                Name: Robert Warshaw
                                                Title: President



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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.