Closing Auction Session: NSE and BSE Start 3 Aug 2026
Why in the news
Both major exchanges brought in a closing auction for equity stocks with F&O contracts on 3 August 2026, acting on a SEBI instruction issued on 16 January 2026.
Key facts
- CAS is a 20-minute daily auction for cash market stocks with derivatives.
- Instead of averaging continuous trades, it pools orders to find one equilibrium closing price.
- Goals: curb closing-time manipulation, improve price discovery and give better benchmarks.
| Phase | Time | What happens |
|---|---|---|
| 1: Transition | 3:15 to 3:20 PM | Continuous trading ends; reference price from VWAP of 3:00 to 3:15 PM trades, ±3% band |
| 2: Order entry | 3:20 to 3:30 PM | Market and limit orders can be changed till 3:25 PM; later only limit orders. Window closes at a random moment in the last two minutes to deter spoofing |
| 3: Matching | 3:30 to 3:35 PM | One price maximising executable volume; market orders get priority |
Exam angle
- Launched together by NSE and BSE.