S&P 500 Slips 1.5%, Nasdaq 100 Drops 4% in Momentum Selloff

The S&P 500 slipped 1.5% to 7,457.69 on Tuesday, while the Nasdaq 100 tumbled 4% in a session that traders said was driven by a unwind of momentum positions. The Dow Jones Industrial Average held up with a fractional loss, reflecting the narrowness of the selling.

The selloff accelerated in the final hour of trading, pushing the Nasdaq 100 to its lowest close in three weeks. Traders pointed to a cluster of stop-loss triggers in large-cap tech names as the primary mechanism. A market participant at a New York-based hedge fund said the firm's momentum models had been long the Nasdaq 100 through the open and flipped to short near the close.

Thursday's weekly jobless claims report is the next scheduled data point that could test the session's low.