As previously announced in our notice Q2005-35 dated March 24, 2005 to Market Data Network RLC Message Users only, to support the rollout of additional options contracts on the CME Globex electronic trading platform, the ISIN codes for several instruments will be changing. The ISIN code is the 12 character alphanumeric identifier for each instrument listed on the CME Globex platform and can be found in positions 1 through 12 of all contract-specific CME Market Data API (CME MD API) messages. CME recommends that customers clear the ISIN codes from existing product tables and reacquire the ISIN codes from the CME MD API MO (m-oh) message on a weekly basis.

Please note that the implementation of these changes, originally scheduled for Sunday, May 1, 2005, has been postponed until Sunday, May 15, 2005. The postponement will allow CME to take remedial action needed to address the CME Globex hardware failure which occurred on Tuesday, April 26, 2005.

The ISIN code changes will be reflected in both the CME production and CME certification environment market data feeds and will impact the following products:

• CME E-mini S&P 500^TM options and options spreads
• CME E-mini NASDAQ-100^® options and options spreads
• CME E-mini Russell 2000^® options and options spreads
• CME Euro FX options and options spreads
• CME Japanese Yen options and options spreads
• CME S&P 500 options
• CME NASDAQ-100 options
• CME S&P 500/Barra Value^TM options
• CME S&P 500/Barra Growth^TM options

If you have any questions regarding this notice, please contact:

Marilee Radecki          mradecki@cme.com              312.930.8193 

Kevin Brady                 kbrady@cme.com                312.648.3653

Thank you.