Exhibit 10.1

FIRST AMENDMENT

This is the First Amendment to the Employment Agreement (the “Agreement”)
entered into between Phupinder Gill (“Employee”) and Chicago Mercantile Exchange
Inc. (“CME” or “Employer”) which became effective on November 7, 2003.

Any capitalized terms used but not defined in this First Amendment shall have
the meaning set forth in the Agreement.

This First Amendment is effective this 20th day of December, 2005. Except as set
forth herein, all provisions of the Agreement shall remain unchanged and in full
force and effect.

Paragraph 2 of the Agreement is hereby amended as follows:

2) Agreement Term. Employee shall be employed hereunder for a term commencing on
January 1, 2004, and expiring on December 31, [2007] 2010, unless sooner
terminated as herein provided (“Agreement Term”). The Agreement Term may be
extended or renewed only by the mutual written agreement of the parties.

Paragraph 6(d) of the Agreement is hereby amended as follows:

  d)   Termination Without Cause. Upon 30 days prior written notice to Employee,
Employer may terminate this Agreement for any reason other than a reason set
forth in sections (a), (b) or (c) of this Section 6. If, during the Agreement
Term, Employer terminates the employment of Employee hereunder for any reason
other than a reason set forth in subsections (a), (b) or (c) of this Section 6:

  (1)   Employee shall be entitled to receive accrued Base Salary through the
date of the termination of his employment, and other employee benefits to which
Employee is entitled upon his termination of employment with Employer, in
accordance with the terms of the plans and programs of Employer; [and]

  (2)   a one time lump sum severance payment equal to 2 times his Base Salary
as of the date of Employee’s termination for the remaining term of the
Agreement, but not more than 24 months of his Base Salary as of the date of the
Employee’s termination, subject to Employee’s execution of a general release in
a form and of a substance satisfactory to CME; and

  (3)   payment of Employee’s premiums for continued coverage under CME’s group
health plan for twelve (12) months beginning the first day of the month
following the date of termination, if Employee elects, and to the extent
Employee is and remains eligible for, such continued coverage under COBRA.

          CHICAGO MERCANTILE EXCHANGE INC.       PHUPINDER GILL
By:/s/ Craig S. Donohue
  By:   /s/ Phupinder Gill
 
       
 
       
Title: Chief Executive Officer
  Title:   President and COO

** Additions have been underlined and deletions have been bracketed.