THE PHILADELPHIA STOCK EXCHANGE TO BEGIN TRADING ONE NEW OPTION ON AUGUST 26

PHILADELPHIA — August 25, 2005- The Philadelphia Stock Exchange (PHLX) announced today that it will begin trading one new option beginning August 26. The option was allocated to Market Street Securities.

Premcor, Inc. (option/stock symbol: PCO) will trade on the March expiration cycle with initial expiration months September, October, December, Janu\ary, and March. Position and exercise limits have been set at 250,000 contracts.

The Philadelphia Stock Exchange was founded in 1790. The PHLX trades 2,000 stocks, 1,703 equity options, 25 sectors index options and currency options and futures. For more information about the PHLX and its products, visit www.phlx.com