Core terms
Limit Up / Limit Down (LULD)
LULD is the U.S. NMS equity plan preventing executions outside upper and lower price bands during regular hours. Under specified conditions, a limit state can lead to a trading pause.
What traders should verify
Bands use an eligible-trade reference, generally over the previous five minutes, and security/session-specific parameters. A limit state unresolved for 15 seconds normally leads to a five-minute pause; verify actual exchange status and reopening arrangements.
Do not conflate
LULD is not the market-wide index circuit breaker, a news halt or SSR. Pauses can be extended, and late-session handling differs. “5% in five minutes” is not the full rule.