Volume on the New York Stock Exchange (search) hit an all-time high during the first hour of trading Friday, the NYSE said.

Today marks quadruple witching (search) -- the quarterly expiration of four different types of June futures and options contracts -- which can lead to greater volume and volatility as investors adjust or exercise their derivative positions at the last minute.

Traders noted that witching was increasing volume in the market.

"Volume is covering up what's actually a slow day on the markets," said Jim Fehrenbach, head of Nasdaq trading at Piper Jaffray in Minneapolis.

In a statement, the New York Stock Exchange said first-hour volume reached an all-time high of 704.4 million shares. That surpassed the previous record set on Sept. 21, 2001, of 660.5 million shares.

Volume was notably high that day, as nervousness in the wake of the Sept. 11 attacks was combined with a triple-witching expiration of U.S. futures and options contracts.