SEC probes big trading firms' role in stock plunge

WASHINGTON (AP) - Federal regulators are looking at whether big trading firms abandoned the market during the massive sell-off on May 6 rather than providing cash support required under law.

Staff of the Securities and Exchange Commission says the possible retreat of big "liquidity providers" during the market plunge is an area of focus in the investigation. Major firms are required by law to remain in the market by buying and selling stocks; smaller firms are not.

Staff members of the SEC and the Commodity Futures Trading Commission were presenting their findings at the first meeting of the two agencies' special advisory committee. The panel is examining the freefall that sent the Dow Jones industrials down nearly 1,000 points in less than 30 minutes.