News Release

NYMEX to Change Margins for Electricity Futures Contracts on NYMEX ClearPort®

Fri May 16 2008

New York, N.Y., May 16, 2008 -- The New York Mercantile Exchange, Inc. today announced margin changes for some of its electricity futures contracts on NYMEX ClearPort, beginning at the close of business on May 19.

The margins for the first through sixth months of the NYISO Zone G and NYISO Zone J peak electricity futures contracts will remain unchanged. Margins for the seventh to 11th months will increase to $3,000 from $2,500 for clearing members, to $3,300 from $2,750 for members, and to $4,050 from $3,375 for customers. Margins for all other months will increase to $3,000 from $2,000 for clearing members, to $3,300 from $2,200 for members, and to $4,050 from $2,700 for customers

Margins for the first month of the Northern Illinois hub and the AEP Dayton hub peak electricity futures contract increase to $10,000 from $9,000 for clearing members, to $11,000 from $9,900 for members, and to $13,500 from $12,150 for customers. Margins for all other months will remain unchanged.

The margins for the first month of the Cinergy Hub LMP peak electricity futures contract will remain unchanged. Margins for the second to sixth months will increase to $5,000 from $4,500 for clearing members, to $5,500 from $4,950 for members, and to $6,750 from $6,075 for customers. Margins for the seventh to 11th months will increase to $6,500 from $5,500 for clearing members, to $7,150 from $6,050 for members, and to $8,775 from $7,425 for customers. Margins for all other months will increase to $5,500 from $4,500 for clearing members, to $6,050 from $4,950 for members, and to $7,425 from $6,075 for customers.

Margins for the ISO New England internal hub peak electricity futures contract will increase to $7,000 from $6,000 for clearing members, to $7,700 from $6,600 for members, and to $9,450 from $8,100 for customers. Margins for the second to sixth months will increase to $8,000 from $7,000 for clearing members, to $8,800 from $7,700 for members, and to $10,800 from $9,450 for customers. Margins for the seventh to 11th months will increase to $9,000 from $8,000 for clearing members, to $9,900 from $8,800 for members, and to $12,150 from $10,800 for customers. Margins for all other months will increase to $6,000 from $5,000 for clearing members, to $6,600 from $5,500 for members, and to $8,100 from $6,750 for customers. 

Margins for the first month of the NYISO Zone G, NYISO Zone J, and ISO New England internal hub off peak electricity futures contracts will increase to $5,000 from $4,500 for clearing members, to $5,500 from $4,950 for members, and to $6,750 from $6,075 for customers. Margins for all other months will remain unchanged.

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Forward Looking and Cautionary Statements 
This press release may contain forward-looking statements within the meaning of the Private Securities Litigation Reform Act, with respect to our future performance, operating results, strategy, and other future events. Such statements generally include words such as could, can, anticipate, believe, expect, seek, pursue, and similar words and terms, in connection with any discussion of future results. Forward-looking statements involve a number of assumptions, risks, and uncertainties, any of which may cause actual results to differ materially from the anticipated, estimated, or projected results referenced in forward-looking statements. In particular, the forward-looking statements of NYMEX Holdings, Inc., and its subsidiaries are subject to the following risks and uncertainties: the success and timing of new futures contracts and products; changes in political, economic, or industry conditions; the unfavorable resolution of material legal proceedings; the impact and timing of technological changes and the adequacy of intellectual property protection; the impact of legislative and regulatory actions, including without limitation, actions by the Commodity Futures Trading Commission; and terrorist activities and international hostilities, which may affect the general economy as well as oil and other commodity markets. We assume no obligation to update or supplement our forward-looking statements.

Contact: Anu Ahluwalia, 212-299-2439 or Keil Decker, 212-299-2209

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