A big change is coming for stock market investors and intraday traders. From August 3, 2026, SEBI will introduce a Closing Auction Session (CAS), changing how the stock market decides the closing price of shares.
According to brokerage platform Zerodha, while market opening hours will remain the same, there will be important changes to market closing timings and intraday auto square-off timings.
If you trade regularly, it’s important to understand these new rules.
New Market Closing Timings from August 3
SEBI’s new Closing Auction Session (CAS) will apply to stocks in the F&O segment, while other market timings will also see slight changes.
Here are the updated timings:
F&O Stocks: Normal trading ends at 3:15 PM, followed immediately by the Closing Auction Session (CAS).
Non-F&O Stocks: Trading will continue until 3:30 PM, with no change.
Index and Stock F&O Contracts: Trading will close at 3:40 PM.
New Auto Square-Off Timings for Intraday Traders
If you use MIS (Margin Intraday Square-off) orders through Zerodha or any other broker, your positions will now be squared off earlier based on the new schedule.
The revised timings are:
F&O Stocks under CAS: 3:10 PM
Non-F&O Stocks: 3:25 PM
Index and Stock F&O Contracts: 3:25 PM
Intraday traders should adjust their trading plans to avoid automatic square-offs.
Why the Closing Price Matters
The closing price of a stock is much more than just the last price seen on the trading screen. It is used for several important financial calculations every day.
The closing price helps determine:
The value of market indices like Nifty and Sensex
The NAV (Net Asset Value) of mutual funds
Settlement of F&O contracts on expiry
Portfolio value and profit/loss reports shown by brokers
Valuation of pledged shares used for margin
Why SEBI Introduced the Closing Auction Session
According to Zerodha, the last traded price (LTP) and the actual closing price are not always the same.
For example, if a stock trades between ₹1,000 and ₹1,010 throughout the day but someone sells a few shares at ₹980 just before the market closes, using ₹980 as the closing price would not accurately reflect the stock’s real market value.
Until now, exchanges used the Volume Weighted Average Price (VWAP) method to reduce such distortions.
From August 3, 2026, SEBI will replace this with the Closing Auction Session (CAS) to make closing prices more transparent and accurate.
If you are an investor or an intraday trader, make sure you understand these new timings and update your trading strategy before the new rules come into effect.