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                                              Exhibit 10.17
                                              Chicago Mercantile Exchange Inc.
                                              Registration Statement on Form S-4

                    THIRD AMENDMENT TO EMPLOYMENT AGREEMENT
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     Reference is hereby made to the Employment Agreement entered into between
the CHICAGO MERCANTILE EXCHANGE ("CME") and FREDERICK ARDITTI ("Arditti") on
October 27, 1998 ("Agreement").  This Third Amendment supercedes the prior First
and Second Amendments.

     The Agreement is hereby amended as follows:

1.   Subparagraph c of Paragraph 5. - Payment Upon Termination or Expiration.
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     Subparagraph c of Paragraph 5 is hereby deleted and replaced in its
     entirety with the following provision.

     In the event of termination by Arditti pursuant to Paragraph 4.d of this
     Agreement, and provided that such termination does not take place prior to
     April 1, 2000, the CME shall:

     (i)    pay Arditti, within thirty days of such termination, a lump sum
            payment, in cash, of $640,385, less appropriate withholding
            representing: (A) Arditti's base salary for a one (1) year period
            following such termination (the "Continuation Period"); and (B)
            Arditti's accrued and unused vacation days as of his date of
            termination. No vacation shall accrue during the Continuation
            Period.
     (ii)   pay Arditti, within thirty days of such termination, a lump sum
            payment, in cash, equal to his then-current non-vested amounts in
            the following plans: Tax Efficient Savings Plan (401K Plan); Pension
            for Employees of the Chicago Mercantile Exchange; Senior Management
            Supplemental Deferred Savings Plan; and Supplemental Executive
            Retirement Plan, less appropriate withholding deductions.
     (iii)  during the Continuation Period, provide Arditti and any covered
            dependents with continued coverage under the CME's health, dental
            and vision insurance program in effect for active employees;
            provided, however, that effective at the end of the Continuation
            Period, health, dental and vision insurance benefits will be
            provided to Arditti and any covered dependents pursuant to the
            Consolidated Omnibus Budget Reconciliation Act ("COBRA"), as set
            forth in Section 4980B of the Internal Revenue Code of 1986, as
            amended, and in Sections 601 through 609 of the Employee Retirement
            Income Security Act. Arditti's contribution and the CME's
            contribution toward the cost of the foregoing
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            coverages shall be determined and paid as though Arditti's
            employment with the CME continued through the end of the
            Continuation Period. The foregoing insurance coverages will earlier
            terminate upon Arditti obtaining other employment which offers
            comparable health insurance coverage and when he first becomes
            eligible for such coverage. Arditti agrees that he will promptly
            notify the CME upon obtaining such coverage from another employer.
            Arditti shall have no duty to seek or obtain other employment.
     (iv)   during the Continuation Period, and subject to CME's discretion,
            either reimburse Arditti for the cost of converting the life and
            accidental death and dismemberment insurance programs referred to in
            the Agreement in effect on the date of Arditti's termination to
            individual coverage, or obtaining equivalent coverage individually,
            or, where applicable, continuing individual coverage already in
            place. It is understood and agreed that Arditti's coverage under the
            CME's disability insurance plan will cease on the date of Arditti's
            termination and that the CME has no obligation to provide or pay for
            other disability coverage. The CME will cooperate with Arditti,
            (e.g., providing documentation) in his efforts to obtain at his
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            expense individual disability coverage.

2.   Paragraph 21. - Mutual General Releases.
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     A new paragraph 21 is hereby added as follows:

     Mutual General Releases.  Except for a claim based upon an alleged breach
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     of this Amendment or Section 7, 9 and 10 of the Agreement, Arditti, for
     himself and for his estate, heirs, personal representatives, executors,
     administrators and assigns, hereby releases and forever discharges the CME,
     any parent, subsidiaries and related and affiliated entities, and each of
     its and their officers, directors, representatives, agents, employees,
     related and participating members, insurers, as well as each of its and
     their respective estates, heirs, personal representatives, executors,
     administrators, successors and assigns (hereinafter collectively and
     individually the "CME Releasees"), and the CME Releasees hereby release and
     forever discharge Arditti, his estate, heirs, personal representatives,
     executors, administrators and assigns, from any and all rights, claims,
     demands, debts, dues, sums of money, accounts, attorneys' fees, complaints,
     judgments, executions, actions and causes of action of any nature
     whatsoever, cognizable at law or equity, past, present or future, which
     either party now has or claims, or might hereafter have or claim, against
     the other party, based upon or arising out of any matter or thing
     whatsoever from the beginning of the world through the date of this
     Amendment, including, without limitation, any claim, action or cause of
     action which was or is related to or arises out of Arditti's employment
     with the CME, or his separation and/or resignation therefrom, or which is
     based upon or arises under this Agreement, or any local, state, or federal
     law dealing with employment, including without limitation Title VII of the
     Civil Rights Act of 1964, the Americans with Disabilities Act and the Age
     Discrimination in
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     Employment Act, the Illinois Human Rights Act, ERISA or any common law tort
     or contract claim.

     The following provisions are applicable to and made a part of this
Agreement and the foregoing general release and waiver:

               (i)    Arditti does not release and waive any right or claim
     which he may have under the Age Discrimination in Employment Act which
     arises after the date of execution of this Third Amendment.

               (ii)   In exchange for this general release and waiver, Arditti
     hereby acknowledges that he has received separate consideration beyond that
     which he is otherwise entitled to under the CME policy, this Agreement, or
     applicable law.

               (iii)  CME hereby expressly advises Arditti to consult with an
     attorney of his choosing prior to executing this Third Amendment which
     contains a general release and waiver.

               (iv)   Arditti has twenty-one (21) days from the date of
     presentment to consider whether or not to execute this Third Amendment. In
     the event of such execution, Arditti has a further period of seven (7) days
     from such date in which to revoke said execution, notice of which must be
     received by Craig Donohue of the CME within such seven (7) day period.

          A new paragraph 22 is hereby added as follows:

          Paragraph 22. - The parties agree and acknowledge that this Amendment
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     shall never be construed as an admission by either of them of any
     liability, wrongdoing, or responsibility on their part.

          A new paragraph 23 is hereby added as follows:

          Paragraph 23. - The parties agree that they shall not disclose the
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     existence of terms of this Agreement to any third party except that: (i)
     with respect to Arditti, his accountants, attorneys and spouse, each of
     whom shall be bound as a condition of this Amendment by this
     confidentiality provision or as may be required to comply with legal
     process, and (ii) with respect to CME in the normal course of its business
     reporting, or as may be required to comply with legal process and reporting
     requirements.

     IN WITNESS WHEREOF, the parties have executed this Agreement as of the date
set forth below.

CHICAGO MERCANTILE EXCHANGE
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By:   ________________________________
      Scott Gordon, Chairman
Date: March 3, 2000


By:   ________________________________
      Frederick Arditti
Date: March 3, 2000