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  <TITLE> Chicago Mercantile Exchange Holdings Inc. (Form: 8-K) </TITLE>
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  		UNITED STATES<BR>
  	SECURITIES AND EXCHANGE COMMISSION
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  	WASHINGTON, D.C. 20549
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  	FORM 8-K
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  	CURRENT REPORT
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  	Pursuant to Section&nbsp;13 or 15(d) of the Securities Exchange Act of 1934
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  	Date of Report (Date of Earliest Event Reported):
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  	&nbsp;
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  	October 16, 2006
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  	Chicago Mercantile Exchange Holdings Inc.
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  <BR>__________________________________________<BR>
  	(Exact name of registrant as specified in its charter)
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  	Delaware
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  	000-33379
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  	36-4459170
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  _____________________<BR>
  	(State or other jurisdiction
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  _____________<BR>
  	(Commission
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  ______________<BR>
  	(I.R.S. Employer
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  	of incorporation)
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  	File Number)
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  	Identification No.)
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  	&nbsp;&nbsp;
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  	20 South Wacker Drive, Chicago, Illinois
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  	60606
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  _________________________________<BR>
  	(Address of principal executive offices)
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  	&nbsp;
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  ___________<BR>
  	(Zip Code)
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  	Registrant&#146;s telephone number, including area code:
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  	312-930-1000
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  	Not Applicable
  <BR>______________________________________________<BR>
  	Former name or former address, if changed since last report
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  	&nbsp;
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  <!-- CoverPageRegistrant END --><P><FONT SIZE="2">
  Check the appropriate box below if the Form 8-K filing is intended to
  simultaneously satisfy the filing obligation of the registrant under any
  of the following provisions:</FONT>
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  <P><FONT SIZE="2">
  [&nbsp;&nbsp;]&nbsp;&nbsp;Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)<br>
  [&nbsp;&nbsp;]&nbsp;&nbsp;Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)<br>
  [&nbsp;&nbsp;]&nbsp;&nbsp;Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))<br>
  [&nbsp;&nbsp;]&nbsp;&nbsp;Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))<br>
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  	Item 5.02 Departure of Directors or Principal Officers; Election of Directors; Appointment of Principal Officers.
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  On October 16, 2006, the Board of Directors of Chicago Mercantile Exchange Holdings Inc. (the "Company") appointed Terrence A. Duffy, the Company&#x2019;s current Chairman, to serve as the Executive Chairman.  The appointment was made in recognition of the substantial role Mr. Duffy plays in the development of the Company&#x2019;s strategic initiatives.  Mr. Duffy will continue to work closely with Mr. Donohue, whose responsibilities as the Company&#x2019;s Chief Executive Officer will remain unchanged.
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  	SIGNATURES
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  	Pursuant to the requirements of the Securities Exchange Act of 1934, the
  	registrant has duly caused this report to be signed on its behalf by the
  	undersigned hereunto duly authorized.
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  	Chicago Mercantile Exchange Holdings Inc.
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  	&nbsp;&nbsp;
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  <I>
  	October 19, 2006
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  	By:
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  <I>
  	Kathleen M. Cronin
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  <I>
  	Name: Kathleen M. Cronin
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  <I>
  	Title: Managing Director, General Counsel and Corporate Secretary
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metadata_documents: [{"type": "8-K", "sequence": "1", "filename": "htm_15667.htm", "description": "LIVE FILING", "secsgml_size_bytes": 8882}]
metadata_filer: {"company-data": {"conformed-name": "CHICAGO MERCANTILE EXCHANGE HOLDINGS INC", "cik": "0001156375", "assigned-sic": "6200", "irs-number": "364459170", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "000-33379", "film-number": "061153580"}, "business-address": {"street1": "20 S. WACKER DR.", "city": "CHICAGO", "state": "IL", "zip": "60606", "phone": "3129303011"}, "mail-address": {"street1": "20 S. WACKER DR.", "city": "CHICAGO", "state": "IL", "zip": "60606"}}
text: Chicago Mercantile Exchange Holdings Inc. (Form: 8-K)
  UNITED STATES
  SECURITIES AND EXCHANGE COMMISSION
  WASHINGTON, D.C. 20549
  FORM 8-K
  CURRENT REPORT
  Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934
  Date of Report (Date of Earliest Event Reported):
  October 16, 2006
  Chicago Mercantile Exchange Holdings Inc.
  __________________________________________
  (Exact name of registrant as specified in its charter)
  Delaware
  000-33379
  36-4459170
  _____________________
  (State or other jurisdiction
  _____________
  (Commission
  ______________
  (I.R.S. Employer
  of incorporation)
  File Number)
  Identification No.)
  20 South Wacker Drive, Chicago, Illinois
  60606
  _________________________________
  (Address of principal executive offices)
  ___________
  (Zip Code)
  Registrant's telephone number, including area code:
  312-930-1000
  Not Applicable
  ______________________________________________
  Former name or former address, if changed since last report
  Check the appropriate box below if the Form 8-K filing is intended to
  simultaneously satisfy the filing obligation of the registrant under any
  of the following provisions:
  [  ]  Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)
  [  ]  Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)
  [  ]  Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))
  [  ]  Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))
  Top of the Form
  Item 5.02 Departure of Directors or Principal Officers; Election of Directors; Appointment of Principal Officers.
  On October 16, 2006, the Board of Directors of Chicago Mercantile Exchange Holdings Inc. (the "Company") appointed Terrence A. Duffy, the Company's current Chairman, to serve as the Executive Chairman.  The appointment was made in recognition of the substantial role Mr. Duffy plays in the development of the Company's strategic initiatives.  Mr. Duffy will continue to work closely with Mr. Donohue, whose responsibilities as the Company's Chief Executive Officer will remain unchanged.
  Top of the Form
  SIGNATURES
  Pursuant to the requirements of the Securities Exchange Act of 1934, the
  	registrant has duly caused this report to be signed on its behalf by the
  	undersigned hereunto duly authorized.
  Chicago Mercantile Exchange Holdings Inc.
  October 19, 2006
  By:
  Kathleen M. Cronin
  Name: Kathleen M. Cronin
  Title: Managing Director, General Counsel and Corporate Secretary