Amendment to Rule 550, Post Settlement Session
December 27, 2005

Page 4 of 4

550.

Clean Copy of Rule Amendments

POST SETTLEMENT SESSION AND POST CLOSE SESSION

After the posting of the settlement price or two minutes after the close of Regular Trading
Hours for pit-and board-traded futures and options contracts, whichever is later, trading may
resume for a period of no longer than three minutes, subject to the following exception. In
the case of Eurodollar and Libor futures, there will be a post close session that shall begin no
earlier than two minutes after the close of pit trading. The post close session shall not be
contingent upon the posting of Eurodollar and Libor futures final settlement prices.

During the post settlement or post close session, members are obligated to bid or offer any
orders that: (1) were received prior to the close; (2) were executable in the closing range; and
(3) are executable in the post settlement or post close session. In addition, members are
obligated to bid or offer any orders, including customer orders, that were received after the
close and are executable in the post settlement or post close session.

The range of prices eligible for trading outright futures or options contracts in the post
settlement session shall be the closing range, with the following exceptions. Trades during
the post settlement session may occur only at the settlement price and the next two ticks in
the direction of the closing range for interest rate contracts excluding Eurodollar and Libor
futures. In Eurodollar and Libor futures, trades during the post close session may occur at
prices that traded during the closing range of pit trading or that traded on Globex (including
bids and offers) from 60 seconds prior to the close of pit trading through the end of the post
close session. For equity index and currency contracts, trades during the post settlement
session may occur at the settlement price, prices within the closing range, or any valid
intervening price between the settlement price and the closing range only. However, on
those days when equity contracts are settled per their "Fair Value" as determined by the
Exchange pursuant to Rule 813.D., trades in the post settlement session in those contracts
shall be within their closing range of prices.

A simultaneous spread or combination transaction executed pursuant to Rule 542 may be
transacted during the post settlement or post close session at a differential which is consistent
with the spread differentials prevailing during the closing range. The price assignment
conventions and conditions set forth in Rule 542 shall apply to any simultaneous spread or
combination transaction executed in the post settlement or post close session.

Except as otherwise specifically set forth in this rule, the rules applicable to trading during

Regular Trading Hours shall be applicable to trading during the post settlement or post close
session.


cme @

Chicago Mercantile Exchange
20 South Wacker Drive 312/930.1000 tel
Chicago, 1L 60606-7499 312/466.4410 fax

www.cme.com

December 27, 2005

Ms. Jean A. Webb

Office of the Secretariat

Commodity Futures Trading Commission
Three Lafayette Centre

1155 21st Street, NW

Washington, DC 20581

RE: Section Sc(c)(1), Part 40.6 - Amendment to the post settlement session
for Eurodollar and LIBOR futures, Rule 550.
CME Submission# 05-138.

Dear Ms. Webb:

Chicago Mercantile Exchange Inc. (“CME” or “Exchange”) hereby notifies the Commission of
an amendment to the post settlement session for Eurodollar and LIBOR futures contracts.

The Exchange certifies that this amendment complies with the Act and rules thereunder.

The Trading Floor Operations Committee (“Committee”) and CME staff reviewed the process of
determining the final settlement prices in the first eight Eurodollar quarterly contract months. Currently,
the prices are derived by using the range of prices (including bids and offers) trading from 1:59 to 2:00
p.m. on CME Globex. As part of this process, Trading Floor Operations staff makes adjustments to the
final settlement price so that consecutive month butterflies and three month calendar spreads are not
violated.

In order for Trading Floor Operations staff to have sufficient time to determine final settlement
prices in the first eight quarterly contract months such that the various spreads are not violated, it was
determined that a change to CME Rule 550 (“Post Settlement Session”) decoupling the start of the post
settlement session from the posting of the final settlement prices was necessary. The change creates a
“post close” session for Eurodollar and Libor futures that will now begin at a fixed time each day,
regardless of whether the final settlement prices have been posted. Additionally, the Committee
determined that the range of prices that should be eligible to trade in the new post close session should
be prices that traded in the pit during the closing range of pit trading in addition to prices that traded on


Amendment to Rule 550, Post Settlement Session
December 27, 2005
Page 2 of 4

CME Globex (including bids and offers) from 60 seconds prior to the close of pit trading through the
end of the post close session in order to ensure that customer orders for pit execution were able to trade
at the most advantageous price existing in the market at the time the order was filled.

These amendments to the post settlement session will become effective on January 9, 2006. Rule
amendments follow below with additions underlined and deletions bracketed and struck out.

If you require any additional information regarding this action, please do not hesitate to contact
Mr. Maz Chadid, Managing Director, Operations at 312-930-8246 or Mr. Eric Wolff, Managing
Director, Regulatory Affairs at 312-930-3255. Please reference our CME Submission #05-138 on all
future correspondence regarding this notification.

Sincerely,

John W. Labuszewski, Director
Research & Product Development

cc: Mr. Thomas M. Leahy and Mr. Steven B. Benton
CFTC Division of Market Oversight, Product Review & Analysis Section



Amendment to Rule 550, Post Settlement Session
December 27, 2005

Page 3 of 4

550.

Text of Rule Amendments
(Additions are underlined, deletions are bracketed and overstruck.)

POST SETTLEMENT SESSION AND POST CLOSE SESSION

After the posting of the settlement price or two minutes after the close of Regular Trading
Hours for pit-and board-traded futures and options contracts, whichever is later, trading may
resume for a period of no longer than three minutes, subject to the following exception. In
the case of Eurodollar and Libor futures, there will be a post close session that shall begin no
earlier than two minutes after the close of pit trading. The post close session shall not be
contingent upon the posting of Eurodollar and Libor futures final settlement prices [trading

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During the post settlement or post close session, members are obligated to bid or offer any
orders that: (1) were received prior to the close; (2) were executable in the closing range; and
(3) are executable in the post settlement or post close session. In addition, members are
obligated to bid or offer any orders, including customer orders, that were received after the
close and are executable in the post settlement or post close session.

The range of prices eligible for trading outright futures or options contracts in the post
settlement session shall be the closing range, with the following exceptions. Trades during
the post settlement session may occur only at the settlement price and the next two ticks in
the direction of the closing range for interest rate contracts excluding Eurodollar and Libor
futures. In Eurodollar and Libor futures, trades during the post close session may occur at
prices that traded during the closing range of pit trading or that traded on Globex (including
bids and offers) from 60 seconds prior to the close of pit trading through the end of the post
close session. For equity index and currency contracts, trades during the post settlement
session may occur at the settlement price, prices within the closing range, or any valid
intervening price between the settlement price and the closing range only. However, on
those days when equity contracts are settled per their "Fair Value" as determined by the
Exchange pursuant to Rule 813.D., trades in the post settlement session in those contracts
shall be within their closing range of prices.

A simultaneous spread or combination transaction executed pursuant to Rule 542 may be
transacted during the post settlement or post close session at a differential which is consistent
with the spread differentials prevailing during the closing range. The price assignment
conventions and conditions set forth in Rule 542 shall apply to any simultaneous spread or
combination transaction executed in the post settlement or post close session.

Except as otherwise specifically set forth in this rule, the rules applicable to trading during
Regular Trading Hours shall be applicable to trading during the post settlement or post close
session.