11.   Another factor is the expiration of stock futures and options Friday, a quarterly occurrence called triple witching, which can prompt heavy selling.

12.   Another factor is the expiration of index futures and index and stock options Friday, a quarterly occurrence called triple witching, which can prompt heavy selling.

13.   Another factor is the expiration of index futures and index and stock options Friday, the quarterly occurrence called triple witching, which often leads to heavy selling.

14.   Another factor is the expiration of stock futures and options Friday, a quarterly occurrence called triple witching, might be contributing to the downturn.

15.   By mid-afternoon, when the indexes had recovered from their lows of the day, analysts said triple witching could have been what was keeping the market down.

16.   Midway through the session, when the indexes had recovered from their lows of the day, analysts said triple witching probably was keeping the market down.

17.   The expiration of stock futures and options Friday, a quarterly occurrence called triple witching, also contributed to the downturn.

18.   The expiration of stock futures and options Friday, a quarterly occurrence called triple witching, also fueled selling in the early going.

19.   The expiration of stock futures and options Friday, a quarterly occurrence called triple witching, also fueled the selling.

20.   The expiration of stock futures and options Friday, a quarterly occurrence called triple witching, contributed to the downturn.