New Closing Price Rules for F&O Stocks: Complete SEBI CAS Timetable & Impact

Last updated: August 2026

SEBI has introduced a new Closing Auction Session (CAS) to decide the final closing price for F&O stocks. Effective August 3, 2026, regular continuous trading for F&O stocks ends at 3:15 PM instead of 3:30 PM. The final cash closing price is decided through a 20-minute auction, while F&O derivative trading continues until 3:40 PM.

Quick Summary: New Market Timings for F&O Stocks

Session / Segment	Old Timing	New Timing (From Aug 3, 2026)	What Happens?
F&O Cash Regular Trading	9:15 AM -3:30 PM	9:15 AM -3:15 PM	Continuous trading stops 15 minutes earlier for F&O stocks.
Reference Price VWAP	3:00 PM -3:30 PM	3:00 PM -3:15 PM	15-minute VWAP sets reference price and ±3% price band.
Closing Auction Session (CAS)	Not Applicable	3:15 PM -3:35 PM	Auction pools orders to find one fair closing price.
Order Entry Session 1	Not Applicable	3:20 PM -3:25 PM	Market and Limit orders allowed within ±3% band.
Order Entry Session 2	Not Applicable	3:25 PM -3:30 PM	Limit orders only. Closes randomly between 3:28–3:30 PM.
Order Matching & Final Price	Not Applicable	3:30 PM -3:35 PM	Orders match at single equilibrium price; close is published.
F&O Derivative Contracts	9:15 AM -3:30 PM	9:15 AM -3:40 PM	Futures and options trade 10 minutes longer.
Post-Close Cash Session	3:40 PM -4:00 PM	3:50 PM -4:00 PM	Trades execute only at the official CAS closing price.
Non-F&O Cash Stocks	9:15 AM -3:30 PM	9:15 AM -3:30 PM	No changes. Normal trading continues until 3:30 PM.

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How Does SEBI’s Closing Auction Session (CAS) Work?

SEBI created CAS to stop last-minute price tricks in the stock market. Earlier, the exchange calculated closing prices using the average price of trades in the last 30 minutes.

Now, the exchange collects buy and sell orders into a single pool. It calculates one single price where the highest number of shares can trade.

This single price becomes the official closing price for the stock. Non-F&O stocks are not affected by this change yet. You can learn the basics of stock market mechanisms through the Signalz Learn Section.

What Happens During the CAS Timetable for F&O Stocks?

The last 45 minutes of the trading day follow a strict timetable. Here is how it works step-by-step:

3:00 PM to 3:15 PM: Reference Price Calculation

Regular trading continues normally. The exchange calculates the average price of all trades in these 15 minutes. This creates the reference price and sets a ±3% price boundary for auction orders.

3:15 PM to 3:20 PM: Transition Period

Regular cash trading pauses for F&O stocks. You cannot place or edit orders in this 5-minute pause. Existing limit orders move automatically to the auction book.

3:20 PM to 3:25 PM: Order Entry Window 1

You can place, change, or cancel both market orders and limit orders. All orders must stay within ±3% of the reference price.

3:25 PM to 3:30 PM: Order Entry Window 2

You can only place or edit limit orders. Market orders are locked. To prevent price manipulation, this window closes at a random second between 3:28 PM and 3:30 PM.

3:30 PM to 3:35 PM: Order Matching

The exchange matches buy and sell orders at the price with the maximum volume. It publishes the official closing price by 3:35 PM. You can follow live updates on our Signalz Feed.

Which Orders Are Allowed During the Closing Auction?

Not all order types can enter the auction. Here is a clear list of allowed and blocked orders:

Limit Orders: Allowed throughout CAS within the ±3% price band.
Market Orders: Allowed only between 3:20 PM and 3:25 PM.
Stop-Loss (SL) Orders: Blocked. Any open SL order cancels automatically at 3:15 PM.
Iceberg / Disclosed Quantity Orders: Blocked. Open orders cancel automatically at 3:15 PM.
GTT Orders: Triggers pause at 3:15 PM for F&O stocks.

For official updates and market announcements, you can review the latest updates published on the NSE India Official Announcements or BSE India Notices websites.

How Does CAS Change Intraday Trading and F&O Rules?

Intraday cash traders must adjust to earlier broker cutoffs. Because regular trading halts at 3:15 PM, brokers auto-square off MIS cash positions earlier, usually between 3:05 PM and 3:10 PM. Check trading rules on Signalz Blogs for broker updates.

Derivatives contracts on F&O stocks get 10 extra minutes. You can trade stock futures and options until 3:40 PM.

This extra time lets you adjust your options positions after seeing the official CAS cash closing price at 3:35 PM. Explore verified advisory models on Signalz Basket Signals or Pay Per Call Signals.

How Our SEBI Advisors Use This Topic

Our SEBI-registered Research Analysts (RAs) track CAS price discovery to build safer expiry trading strategies. Since cash trading ends at 3:15 PM while F&O continues until 3:40 PM, advisors spot price gaps between options and the underlying stock close.

Signalz RAs use this 25-minute window to recommend adjustments and manage risk before market close. Connect directly with SEBI advisors through our Signalz Mentors Marketplace.

Frequently Asked Questions (FAQs)

What is the new closing price rule for F&O stocks?

The closing price for F&O stocks is now set by a 20-minute auction called CAS between 3:15 PM and 3:35 PM, replacing the 30-minute average calculation.

Why did SEBI introduce the Closing Auction Session?

SEBI introduced CAS to stop price manipulation near market close and help large trades execute at a fair market price.

What happens to my intraday MIS orders for F&O stocks?

Brokers will square off intraday equity orders earlier, typically around 3:05 PM to 3:10 PM, before regular trading halts at 3:15 PM.

Can I trade F&O contracts after 3:30 PM?

Yes. Futures and options contracts trade until 3:40 PM, giving you 10 extra minutes after cash market trading ends.

Do these new CAS rules apply to non-F&O stocks?

No. Non-F&O stocks continue regular continuous trading until 3:30 PM without any change to their closing price calculation.

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