Overview
- The National Stock Exchange implemented the revised pre-open rules on Monday, September 7, 2026, keeping the 9:00–9:15 overall window but changing how and when orders are entered.
- Order entry is now split into two five-minute windows: both market and limit orders are allowed from 9:00–9:05, and only limit orders are accepted from 9:05–9:10 with market orders submitted then rejected.
- The exchange may close order collection at random between 9:08 and 9:10, and matching for opening price discovery has been moved to 9:10–9:12 followed by a 9:12–9:15 transition to continuous trading.
- Under the new matching sequence market orders that can match with other market orders get first priority by time, remaining market orders match against limit orders by price‑time, and any leftover limit orders match by price‑time.
- Brokers, algo firms and retail platforms must update routing and client guidance to avoid rejected orders and to manage price certainty, and the change is intended to reduce late‑minute gaming and better align cash and derivatives price discovery.