News Release

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

Wed Aug 20 2008

New York, NY, August 20, 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 tomorrow.

Margins for the first month of the PJM Western Hub LMP peak monthly electricity futures contract will decrease to $11,000 from $12,000 for clearing members, to $12,100 from $13,200 for members, and to $14,850 from $16,200 for customers. Margins for the second to fourth months will decrease to $6,000 from $7,000 for clearing members, to $6,600 from $7,700 for members, and to $8,100 from $9,450 for customers. Margins for the fifth and sixth months will decrease to $5,000 from $6,000 for clearing members, to $5,500 from $6,600 for members, and to $6,750 from $8,100 for customers. Margins for the seventh and eighth months will decrease to $3,500 from $4,500 for clearing members, to $3,850 from $4,950 for members, and to $4,725 from $6,075 for customers. Margins for the ninth and 10th months will decrease to $2,500 from $3,500 for clearing members, to $2,750 from $3,850 for members, and to $3,375 from $4,725 for customers. Margins for the 11th and 12th months will decrease to $2,000 from $3,000 for clearing members, to $2,200 from $3,300 for members, and to $2,700 from $4,050 for customers. Margins for the 13th to 16th months will decrease to $3,000 from $4,000 for clearing members, to $3,300 from $4,400 for members, and to $4,050 from $5,400 for customers. Margins for all other months will decrease to $2,500 from $3,500 for clearing members, to $2,750 from $3,850 for members, and to $3,375 from $4,725 for customers. 

Margins for the first to sixth months of the NYISO Zone A peak electricity futures contract will decrease to $3,000 from $4,000 for clearing members, to $3,300 from $4,400 for members, and to $4,050 from $5,400 for customers. Margins for the seventh to 12th months will decrease to $1,500 from $2,500 for clearing members, to $1,650 from $2,750 for members, and to $2,025 from $3,375 for customers. Margins for all other months will decrease to $1,000 from $2,000 for clearing members, to $1,100 from $2,200 for members, and to $1,350 from $2,700 for customers.

Margins for the first month of the NYISO Zone G peak electricity futures contract will decrease to $7,000 from $8,800 for clearing members, to $7,700 from $8,800 for members, and to $9,450 from $10,800 for customers. Margins for the second to sixth months will decrease to $4,500 from $5,500 for clearing members, to $4,950 from $6,050 for members, and to $6,075 from $7,425 for customers. Margins for the seventh to 12th months will decrease to $3,000 from $4,000 for clearing members, to $3,300 from $4,400 for members, and to $4,050 from $5,400 for customers. Margins for all other months will decrease to $2,000 from $3,000 for clearing members, to $2,200 from $3,300 for members, and to $2,700 from $4,050 for customers. 

Margins for the first month of the NYISO Zone J peak electricity futures contract will decrease to $8,000 from $9,000 for clearing members, to $8,800 from $9,900 for members, and to $10,800 from $12,150 for customers. Margins for the second to sixth months will decrease to $5,500 from $6,500 for clearing members, to $6,050 from $7,150 for members, and to $7,425 from $8,775 for customers. Margins for the seventh to 12th months will decrease to $3,000 from $4,000 for clearing members, to $3,300 from $4,400 for members, and to $4,050 from $5,400 for customers. Margins for all other months will decrease to $2,000 from $3,000 for clearing members, to $2,200 from $3,300 for members, and to $2,700 from $4,050 for customers.

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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 Tara Stowe, 212-299-2455

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