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                                                                   EXHIBIT 10.15

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                              TERMINATION AGREEMENT

      This TERMINATION AGREEMENT (the "Agreement") is entered into as of this
31st day of December, 2002 by and between MARK D. NIENSTEDT, individually and on
behalf of all his successors, heirs, executors, administrators, legal
representatives, and assigns (hereinafter referred to collectively as
"Nienstedt"), and INSTINET GROUP INCORPORATED, on behalf of its parents,
subsidiaries, divisions and affiliates, and their respective predecessors,
successors, assigns, representatives, officers, directors, shareholders, agents,
employees and attorneys (hereinafter referred to collectively as "Instinet" or
the "Company").

                                   WITNESSETH:

      WHEREAS, Nienstedt entered into an Employment Agreement with Instinet
dated April 2, 2001 (the "Initial Employment Agreement"), which provided for
Nienstedt to be employed as the Chief Financial Officer of the Company;

      WHEREAS, in April 2002, the Initial Employment Agreement was amended in
part to provide for Nienstedt's appointment as Acting President and Chief
Executive Officer of the Company;

      WHEREAS, Nienstedt and Instinet desire to terminate the Initial Employment
Agreement as amended in all respects, to be replaced and superseded by a new and
subsequent Employment Agreement (the "New Employment Agreement"), with different
terms and conditions governing Nienstedt's relationship with Instinet;

      WHEREAS, Nienstedt and Instinet have reached agreement with respect to all
matters arising out of Nienstedt's Initial Employment Agreement and the
termination thereof;

      NOW, THEREFORE, in consideration of the mutual convenants and undertakings
set forth herein, Nienstedt and Instinet agree as follows:


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      1. Termination of Agreement. By mutual agreement between the parties, in
accordance with the provisions of this Termination Agreement, the Initial
Employment Agreement shall terminate in all respects on December 31, 2002 (the
"Termination Date"), and shall have no further force or effect after the
Termination Date. Nienstedt's employment with Instinet, however, will continue
pursuant to the terms and conditions of the New Employment Agreement.

      2. Vested Payments and Benefits. This Termination Agreement shall not
alter or affect in any way Nienstedt's vested and accrued rights, if any, to
payments and benefits pursuant to any employee benefit, welfare, retirement or
equity plan maintained by Instinet.

      3. Termination Payments and Benefits. Instinet agrees to pay Nienstedt the
amounts described below, subject to the provisions of this Termination
Agreement. The payments to be provided by the paragraph are in place of, and not
in addition to, payments Nienstedt would otherwise be entitled to pursuant to
the Initial Employment Agreement or any policy or practice of Instinet. All
payments made pursuant to this paragraph will be reduced by all applicable
payroll deductions including, but not limited to, federal, state and local tax
withholdings. Instinet agrees to pay Nienstedt an aggregate of $2,500,000, by
making the following installment payments by no later than the dates indicated
on the schedule below:

      February 28, 2003        $1,366,666

      February 28, 2004        $  566,667

      February 28, 2005        $  566,667

      The period from January 1, 2003 through February 28, 2005 shall be
referred to herein as the "Termination Payment Period."

      4. Limited Release. In consideration of the promises herein, Nienstedt
releases and discharges Instinet, from any and all liability, and waives any and
all rights of any kind and description that he has or may have against Instinet
as of the date of this Termination Agreement, including, but not limited to,
claims arising under any federal, state and local fair


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employment practice law, workers' compensation law, and any other employee
relations statute, executive order, law and ordinance, including, but not
limited to, Title VII of the Civil Rights Act of 1964, as amended, the Age
Discrimination in Employment Act of 1967, as amended, the Rehabilitation Act of
1973, as amended, the Family and Medical Leave Act, the Americans With
Disabilities Act of 1990, as amended, the Civil Rights Acts of 1866 and 1871,
and, except as otherwise expressly set forth herein, of any other duty and/or
other employment related obligation, tort, tortious course of conduct, contract,
public policy, statute, common law, and equity, and claims for wages and
benefits, monetary and equitable relief, punitive and compensatory relief, and
attorneys' fees and costs, arising from the Initial Employment Agreement. The
foregoing notwithstanding, such releases and waivers do not apply to: (a) any
rights arising out of this Agreement; (b) any of Nienstedt's accrued benefits
which have vested under the terms of the qualified benefit and retirement plans
maintained by Instinet as such plans may be amended from time to time; (c) any
rights that Nienstedt may have to indemnification under Instinet's general
corporate indemnity for acts undertaken by Nienstedt within the scope of his
duties while employed at Instinet.

      5. Non-Competition Covenant. Nienstedt agrees that he will not through the
Termination Payment Period, directly or indirectly, engage as officer, employee,
agent, partner, or substantial stockholder of, or permit his name to be used by
or in connection with, any business which shall provide securities brokerage or
financial services through the Internet or any similar medium of electronic
commerce (including without limitation the business of an ECN, ATS or their
equivalent), from an operational base located anywhere within the United States.
This Section shall not, however, prevent Nienstedt from being employed by, or
serving as a director of, an entity that is in such business, provided that
Nienstedt is not personally involved in the day-to-day activities of such entity
in such area.

      6. Non-Solicitation Covenant. Nienstedt further agrees that he will not:
(i) through the Termination Payment Period, directly or indirectly solicit any
employee of Instinet to leave the employ of Instinet; or (ii) through the
Termination Payment Period, directly or indirectly initiate contact with any
Instinet client to induce that client to transact with any other company
business in which Instinet is engaged, including electronic order-matching,


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institutional equities, clearing and after-hours trading, or to reduce or
refrain from doing any such business with Instinet.

      7. Entire Agreement; Severability.

      (a) Entire Agreement. This Termination Agreement constitutes the entire
agreement among the parties hereto with respect to the subject matter hereof.
The Initial Employment Agreement, all prior correspondence and proposals, and
all prior promises, representations, understandings, arrangements and agreements
relating to such subject matter are merged herein and superseded hereby.

      (b) Severability. This Agreement constitutes the complete settlement of
all issues and disputes arising from the Initial Employment Agreement between
Nienstedt and Instinet as of the date hereof, and may not be modified except by
a suitable writing signed by both Nienstedt and Instinet. Nienstedt and Instinet
have entered into this Agreement voluntarily, knowingly, and upon advice of
counsel. If any provision of this Agreement is held to be invalid, the remaining
provisions shall remain in full force and effect.

      8. Execution.

      Nienstedt acknowledges that he has been provided an opportunity of up to
twenty-one (21) days from his receipt of this document to review it. Following
his signing of the Agreement, Nienstedt has the right to revoke the Agreement at
any time within seven (7) calendar days of his signing it, not including the
date of his signing (the "Revocation Period"). Notice of Revocation shall be
given in writing and sent by overnight mail no later than the seventh day
following the date Nienstedt signs this Agreement to General Counsel, Instinet
Corporation, 3 Times Square, New York, NY 10036.

      9. Governing Law; Venue. This Termination Agreement shall be governed by
and construed in accordance with the law of the State of New York. An action for
breach of this Termination Agreement may be brought in any court of competent
jurisdiction located in New York.


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                                                                  EXECUTION COPY

      THE UNDERSIGNED, intending to be legally bound, have executed this
Agreement on this 31st day of December, 2002.


MARK D. NIENSTEDT                              INSTINET GROUP INCORPORATED


/s/ Mark D. Nienstedt                      By: /s/ Edward J. Nicoll
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                                               Edward J. Nicoll
                                               Chief Executive Officer

THIS IS A RELEASE. READ CAREFULLY BEFORE SIGNING.


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