Nothing works perfectly at 600 million shares, particularly with 500 points down on the Dow.

Volume stood at 3.7 million shares, with most of them flowing into professional hands.

Volume was relatively light for the third day in a row, at 721.7 million shares.

It was the second most heavily traded stock of the day, at 4.2 million shares.

The exchange's previous high was set in September, at 112.1 million shares.

At more than 8 million shares traded, the stock was yesterday's most active.

Volume on the big board remained moderate at 161.8 million shares.

The previous record short interest position was set in October, at 1.79 billion shares.

And short interest in the stock, which stood at 5.37 million shares as of July 10, remains high.

It was also the most active stock, at 16.1 million shares.