The stock market doesn’t simply switch on at 9:15 AM and off at 3:30 PM. There are two additional sessions, one before the regular market opens and one after it closes. Here’s how each one works.

Pre-market session: 9:00 AM – 9:15 AM

The pre-market session runs for 15 minutes before regular trading begins and has three windows:

1. 9:00 AM – 9:05 AM, Order entry (Phase 1): Place, modify, or cancel both limit and market orders.
2. 9:05 AM – 9:10 AM, Order entry (Phase 2): Only limit orders can be placed, modified, or cancelled, and market orders are rejected. The exchange closes order entry at a random moment between 9:08 and 9:10.
3. 9:10 AM – 9:12 AM, Order matching: The exchange determines the opening price through a call auction and confirms trades. No new orders can be placed. Matching starts right after order entry closes, so it can begin before 9:10.
4. 9:12 AM – 9:15 AM, Buffer period: Transition window before regular trading begins at 9:15 AM. No order activity permitted.

This session helps reduce sharp price gaps at market open by collecting orders in advance and discovering the opening price through an auction.

Pre-open session for futures contracts

Futures contracts follow the same 9:00 AM – 9:15 AM pre-open window, with two restrictions:

• Only current month contracts can be traded
• In the 5 trading days before a contract’s expiry, only the next month’s contract can be traded in pre-open. 

Post-market session: 3:50 PM – 4:00 PM

After the regular market closes at 3:30 PM, the post-market session runs from 3:50 PM to 4:00 PM.