Indian stock market timings will change from Monday, August 3, as SEBI's new Closing Auction Session (CAS) framework comes into effect for select stocks. The biggest change will be for stocks that are eligible for futures and options trading, where a new auction process will determine the official closing price.
The changes are aimed at making the closing price more transparent and improving price discovery, especially for stocks with active derivatives trading. SEBI introduced the framework to bring India's market structure closer to practices followed by major global exchanges.
What Changes From August 3?
For F&O-eligible stocks in the equity cash market, normal trading will end at 3:15 pm. A transition period will then run until 3:20 pm.
The new Closing Auction Session will begin at 3:20 pm. During the first five minutes, from 3:20 pm to 3:25 pm, investors can place both market and limit orders.
The next five-minute window, from 3:25 pm to 3:30 pm, will allow only limit orders. Market orders cannot be modified or cancelled during this phase. The order-entry period will also close randomly during the final two minutes to prevent traders from gaining an advantage by timing their orders.
Order matching will take place between 3:30 pm and 3:35 pm. The price discovered through this process will become the official closing price for the stock. SEBI's framework provides for a 20-minute CAS running from 3:15 pm to 3:35 pm.
The change matters because closing prices are widely used by mutual funds, index funds and other investors to value portfolios and calculate returns. SEBI said the auction can bring more liquidity together at one price and create a fairer closing price for investors.
F&O Trading Gets 10 More Minutes
The equity derivatives market will also get a longer trading window.
F&O trading will continue until 3:40 pm, giving traders an additional 10 minutes after the regular cash market session ends.
This change is designed to keep the cash and derivatives markets better aligned after the introduction of the closing auction process.
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Non-F&O Stocks Remain Unchanged
The new auction mechanism will initially apply to stocks that have equity derivatives available. For other stocks, the existing closing-price mechanism will continue. Their regular trading session will end at 3:30 pm.
This means investors will need to pay attention to whether a stock is part of the F&O segment before placing orders near the market close.
Why Is SEBI Changing The Closing Price System?
Until now, the closing price for stocks was generally based on the volume-weighted average price of trades during the final 30 minutes of continuous trading.
SEBI's new system shifts the focus to an auction, where buy and sell interest is collected and matched to discover a single closing price. The regulator said this can improve execution for large orders, provide equal access to investors and reduce tracking errors for passive funds.
The change is also significant for institutional investors because the closing price is used for portfolio valuation and several investment-related calculations.
Pre-Open Session Also Gets Revised
SEBI has also changed the pre-open auction process. The pre-open session will continue to run before normal trading begins at 9:15 am, with order entry followed by order matching and a transition period.
The broader objective is to make price discovery more orderly at both ends of the trading day.
For investors, the key takeaway is simple: from August 3, F&O-eligible stocks will have a new closing auction between 3:15 pm and 3:35 pm, while equity F&O trading will continue until 3:40 pm.
The National Stock Exchange has already issued operational information and conducted mock trading ahead of the implementation.
Also Read: SEBI Bars Zee's Punit Goenka, Subhash Chandra For One Year, Imposes Rs 1.48 Crore Fine
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