Closing Auction Session (CAS) has been introduced:
To make a stock’s closing prices fairer, more transparent, and market-driven
To reduce price manipulation near market close
To align Indian markets with global best practices

Was this article helpful?      YES      NO

Initially, Closing Auction Session (CAS) is being implemented for stocks that are also traded in the Derivatives market, also known as Futures & Options (F&O). Other stocks will continue normal trading till 3:30 PM. Expansion to more stocks will happen in phases.

Was this article helpful?      YES      NO

For CAS stocks:

For Non-CAS stocks:

Trading continues till 3:30 PM as usual.

Was this article helpful?      YES      NO

Closing Auction Session (CAS) has 3 key phases:

Was this article helpful?      YES      NO

Yes, but with some restrictions:
•    3:20 to 3:25 PM:
      Limit orders
      Market orders

•    3:25 to 3:30 PM:
      Only limit orders allowed
      No market orders allowed

Was this article helpful?      YES      NO

These order types are not allowed in Closing Auction Session (CAS):
 Stop-loss orders
 Disclosed quantity (iceberg) orders
 IOC orders
 Market orders after 3:25 PM
 BigTrade (Margin Intraday Square-off orders)
BigTrade (Margin Intraday Square-off Plus orders)

Was this article helpful?      YES      NO

Regular orders continue into Closing Auction Session (CAS). But the following orders will get cancelled: 
 Stop-loss orders
 Disclosed quantity orders
Orders outside price band

Was this article helpful?      YES      NO

In a Closing Auction Session (CAS), the closing price is calculated based on an auction matching system (not average price), called equilibrium price, which is:
The price at which maximum trades happen
The price at which there is minimum imbalance between buyers and sellers
If no price is found, the reference price is used.

Was this article helpful?      YES      NO

The reference price in a Closing Auction Session (CAS) is usually the VWAP of trades from 3:00 to 3:15 PM, with these conditions:
  If no trades: last traded price
  If no trades the whole day: previous close

Was this article helpful?      YES      NO

During a Closing Auction Session (CAS):
  Orders must be within ±3% of reference price
  Orders outside this range will be rejected or cancelled

Was this article helpful?      YES      NO

Yes, you will see:

   Indicative closing price
   Buy/Sell quantities
   Demand-supply imbalance
   Indicative index

Was this article helpful?      YES      NO

Trades are executed only once between 3:30 and 3:35 PM. All orders are matched at one final price (closing price).

Was this article helpful?      YES      NO

If your order did not get executed during a Closing Auction Session (CAS), it will be cancelled (depending on the order type).

Was this article helpful?      YES      NO

A Closing Auction Session (CAS) is only for Equity (Cash market). However, since F&O trading is extended till 3:40 PM, price bands in Futures reset near the CAS.

Was this article helpful?      YES      NO

Yes. Each exchange runs a Closing Auction Session (CAS) independently. Prices may differ slightly.

Was this article helpful?      YES      NO

Yes. Post-closing session (3:50 to 4:00 PM) is available. There will be limited trading at the closing price.

Was this article helpful?      YES      NO

In case of extraneous circumstances, such as circuit breaker being breached, the Closing Auction Session (CAS) may be skipped entirely. Closing price will then follow the old method (VWAP/LTP).

Was this article helpful?      YES      NO

Closing Auction Session (CAS) starts August 3, 2026, onwards.

Key Takeaways for Traders
The market effectively ends at 3:15 PM for F&O stocks. Final price is decided via auction, not averaging. Be cautious of: 
   Restricted order types
   Narrow price bands (±3%)
It’s important for: 
   Intraday traders
   Closing price strategies
   Index tracking

Was this article helpful?      YES      NO