SEBI New Market Timings 2026: CAS, F&O Expiry & VWAP Settlement Rules Explained
Published: October 17, 2026 · Category: SEBI Updates, Indian Stock Market, F&O Education
SEBI New Market Timings 2026: Closing Auction Session, F&O Expiry and VWAP Settlement Rules Explained
India's market closing process is set for an important update. The Securities and Exchange Board of India (SEBI) issued a revised framework on October 15, 2026, covering the Closing Auction Session (CAS), trading cut-off times for index and stock derivatives, and the calculation of settlement prices for expiring derivatives contracts.
Most of the announced changes are scheduled to take effect on December 7, 2026. Specific provisions for the transition of eligible unexecuted limit and iceberg orders are scheduled to begin later, on February 8, 2027. The dates and detailed procedures should be checked against the latest SEBI circulars and exchange implementation notices before you trade.
This guide explains the changes in plain English, with a timings table, examples of VWAP calculations, practical considerations for traders and answers to common questions. It is designed for Indian market readers who follow the Nifty, Bank Nifty, cash equities, stock futures and options.
Important: This article is educational, not investment advice. Regulatory procedures can be clarified or updated. Confirm the latest official instructions from SEBI, NSE, BSE and your broker.
SEBI's Revised Market Timings: Quick Summary
The table below provides a quick overview of the timings and settlement changes described in the October 15, 2026 framework. It is a reader-friendly summary, not a substitute for the full circular or contract-specific exchange notices.
| Market activity | Revised framework |
|---|---|
| Closing Auction Session (CAS) | 3:30 PM to 3:40 PM |
| Index derivatives on non-expiry days | Scheduled to trade until 3:45 PM |
| Expiring index derivatives on expiry day | Trading ceases at 3:30 PM |
| Stock derivatives, including expiry days | Scheduled to trade until 3:45 PM |
| Post-close cash-market session | 3:50 PM to 4:00 PM |
| Expiry settlement | Prescribed 30-minute VWAP methodology |
| Specified order-transition provisions | February 8, 2027 |
Key distinction: Do not treat all derivatives contracts as having the same expiry-day cut-off. The framework distinguishes expiring index derivatives from stock derivatives. Check the contract type and latest exchange notice.
1. What Is the Closing Auction Session?
The Closing Auction Session is a defined market process used to determine the closing price of eligible securities through an auction. In continuous trading, buy and sell orders can match throughout the session when prices and quantities are compatible. In an auction, eligible orders are collected and processed under a specific set of rules to establish an equilibrium price and match trades.
Closing prices are important reference points. Investors use them to calculate daily returns, review portfolio performance and compare stocks against market indices. Asset managers may also use closing values when evaluating how closely a fund follows its benchmark. A structured auction creates a defined process for price discovery at the end of the day.
Under the revised framework, CAS is scheduled to run from 3:30 PM to 3:40 PM. The auction is separate from the ordinary continuous trading session. Its order-entry stages, permitted order types and closing process are governed by the relevant rules.
A closing auction does not guarantee that every order will execute or that every participant will agree with the resulting price. It provides a structured mechanism for arriving at the closing price of securities covered by the framework.
2. How the Closing Auction Session Works
Market orders and limit orders behave differently. A market order generally prioritises execution at the best available price under the applicable rules. A limit order specifies a maximum price a buyer will pay or a minimum price a seller will accept. A limit order offers more control over price, but execution is not guaranteed.
The revised CAS framework divides the session into stages. The reference-price calculation and transition into the auction begin at 3:30 PM. The subsequent order-entry periods distinguish between market and limit orders, and the auction's order-entry window closes at a system-selected random time in the final part of the session.
The exact order-entry rules matter. Traders should not assume they can submit, modify or cancel every order type throughout the entire ten-minute period. The official circular and exchange notices define which actions are permitted at each stage, as well as how matching and publication of the closing price occur.
Why is the closing time random within the final window?
If everyone knows the precise final second when an auction will close, some participants may have an incentive to wait until that moment to change an order. A random system-controlled close within the prescribed window reduces the predictability of the exact cut-off. It does not eliminate volatility, guarantee a particular price or remove all execution risk.
3. Why the Closing Price Matters
The closing price is used throughout the financial industry. Retail investors compare it with the previous close to understand daily movement. Portfolio managers may use closing prices to value holdings and assess performance. Funds that follow an index may also monitor closing values when measuring tracking differences.
A defined auction may concentrate eligible orders around the end of the session and provide a more systematic method of determining the closing price. Its practical effect will depend on participation, liquidity, eligible securities and the way market participants use the new process.
Investors should avoid assuming that the auction will always reduce volatility or that the final price will always be closer to a preferred theoretical value. The auction is a price-discovery mechanism, not a guarantee of a specific market outcome.
4. CAS Reference Price vs. Derivatives Expiry Settlement Price
One of the most important details in the revised framework is the difference between the reference price used for CAS and the settlement price used for expiring derivatives. These are related but distinct calculations.
CAS reference price: last 15 minutes
The revised framework describes the CAS reference price for eligible securities as being based on the volume-weighted average price (VWAP) of trades during the final 15 minutes of continuous trading. Fallback rules apply if there are no trades in the relevant period or if no trade has occurred during the day. The exact fallback depends on the conditions set out in the official framework, including the applicable previous closing price and corporate-action adjustments.
Expiry settlement: last 30 minutes
For expiry settlement, the revised framework retains a separate 30-minute VWAP methodology. Index derivatives use the prescribed index value calculated from the VWAPs of constituent securities during the relevant period. Stock derivatives use the prescribed VWAP of the underlying stock across exchanges.
That means the 15-minute CAS reference-price window is not the same as the 30-minute derivatives settlement window. The former is used in the closing auction process; the latter is used to calculate the settlement value for expiring derivatives under the applicable methodology.
5. Revised F&O Timings: Index vs. Stock Derivatives
Futures and options (F&O) are derivative contracts whose values depend on an underlying asset, such as a stock or an index. Because index derivatives and single-stock derivatives have different underlying references, traders need to check the exact contract type and expiry status before relying on a cut-off time.
Index futures and options
On non-expiry days, index derivatives are scheduled to trade until 3:45 PM. On the expiry day of an index derivatives contract, trading in the expiring contract is scheduled to cease at 3:30 PM.
This matters to traders who manage expiring index options or futures during the final part of the session. An order-management plan that assumes the contract can be traded until 3:45 PM may not fit the revised rule for an expiring index contract. Check the expiry calendar, contract details and broker platform before the session.
Stock futures and options
Stock derivatives are scheduled to continue trading until 3:45 PM, including on expiry days, under the announced framework. This is a different cut-off from the one specified for expiring index derivatives.
Do not apply a single generic "F&O closing time" to every instrument. The correct time depends on the contract and whether the relevant contract is expiring that day. Exchange notices and broker implementation instructions should be treated as the operational reference.
6. What Is VWAP? A Simple Example
VWAP stands for Volume Weighted Average Price. It calculates an average transaction price while giving more weight to prices at which more shares traded. The basic formula is:
VWAP = Total value of eligible trades ÷ Total quantity traded
Imagine a hypothetical stock records the following trades during a measurement window:
- 100 shares at ₹500
- 300 shares at ₹502
- 600 shares at ₹501
The total traded value is (100 × ₹500) + (300 × ₹502) + (600 × ₹501), which equals ₹5,01,200. The total quantity is 1,000 shares. The illustrative VWAP is therefore ₹5,01,200 divided by 1,000, or ₹501.20.
This example shows why VWAP differs from a simple average of trade prices. The calculation gives more weight to the ₹501 price because more shares traded there. Actual expiry settlement uses the prescribed period, eligible data and exchange methodology; this simplified example is not an official settlement calculation.
7. How Index Derivatives Settlement Works
An index derivative is linked to an index made up of multiple securities rather than to one individual company. Under the revised framework, expiry settlement uses the prescribed index value calculated from the VWAPs of the index's constituent securities during the last 30 minutes of continuous trading in the equity cash market.
That means the official settlement value should not be assumed to be identical to a single live index tick, one constituent's last trade or the CAS closing price. The prescribed calculation and the final value published under the exchange rules determine the settlement outcome.
Indicative values can help market participants follow the evolving calculation, but an indicative value should not automatically be treated as the final settlement value. Traders should refer to official exchange information for the final figure.
8. How Stock Derivatives Settlement Works
Stock futures and options derive their value from an individual listed stock. Under the revised framework, the expiry settlement calculation uses the prescribed VWAP of the underlying stock across exchanges during the last 30 minutes of continuous trading.
The last traded premium of an option is not necessarily the same as its final settlement value. An option premium can change with the underlying price, volatility, time remaining and market conditions. The official settlement calculation follows the applicable exchange methodology, not a trader's preferred quote or a random screen snapshot.
Traders should distinguish between displayed unrealised profit or loss during the session and the final settlement amount calculated under the contract rules. If a position is held close to expiry, understanding the settlement methodology is part of understanding its risk.
9. The Post-Close Cash-Market Session
The revised framework provides for a post-close cash-market session from 3:50 PM to 4:00 PM. This session takes place after the CAS and operates under its own rules. It should not be confused with continuous trading or with the auction itself.
Under the applicable post-close arrangements, trades are executed at the relevant closing prices of eligible securities. Investors should not assume that every stock, order type or broker platform feature is available in this session. Check the latest exchange instructions before placing an order.
10. Unexecuted Limit Orders and Iceberg Orders
The revised framework also addresses how eligible unexecuted orders transition from continuous trading into CAS. The specified provisions concerning unexecuted limit and iceberg orders are scheduled to take effect on February 8, 2027, later than the main implementation date.
A limit order sets a maximum purchase price or minimum selling price. It may remain unexecuted if the market does not reach a price that allows a match under the applicable rules. An iceberg order displays only a portion of a larger order at a time, subject to the platform's rules.
The framework describes how eligible orders may transition, subject to exclusions, price-band conditions and other requirements. Eligible iceberg orders may be converted into fully disclosed limit orders under the prescribed provisions. Order eligibility and handling must be checked against the official rules.
Do not assume that every open order will automatically carry forward unchanged. Order type, price, quantity, priority, stop-loss restrictions and exchange-system rules can matter. If you regularly place orders near the close, review your broker's implementation guidance before the transition date.
11. What Traders Should Do Before December 7, 2026
- Review the expiry calendar. Identify which contracts you trade and the dates on which they expire.
- Confirm contract cut-off times. Remember the distinction between expiring index derivatives and stock derivatives.
- Learn the settlement calculation. Understand the difference between the 15-minute CAS reference price and the 30-minute VWAP settlement methodology.
- Review open orders. Check how your broker will handle eligible limit and iceberg orders under the later transition provisions.
- Read exchange notices. Regulatory circulars may be accompanied by implementation instructions from exchanges and brokers.
- Avoid headline-driven trades. A change in market structure does not guarantee a profit or predict the direction of the market.
12. Will the Changes Reduce Volatility?
It is too early to conclude that the revised timings will automatically reduce volatility. A structured auction and a defined settlement methodology can change how prices are determined, but they do not guarantee a smooth closing price.
Prices can still move sharply when new information arrives, liquidity changes or market participants adjust positions. VWAP can reduce the weight given to an isolated trade compared with a simple last-traded-price reference, but it cannot eliminate all market risk. The result depends on actual trading activity during the prescribed period.
Investors should wait for implementation experience and official market data before making broad claims about changes to liquidity, spreads, volatility or transaction costs.
13. Could Retail Traders Be Affected?
The changes may be particularly relevant to retail traders who manage positions near the close or hold derivatives contracts on expiry day. The exact impact depends on the instrument, the trading strategy and the final implementation details.
A trader managing an expiring index option will need to plan around the earlier cut-off. A trader using limit or iceberg orders near the close should understand the transition rules and broker instructions. A long-term cash-equity investor who rarely trades near the close may notice less day-to-day change, but the closing-price mechanism remains relevant when reading market reports and historical charts.
Derivatives can involve substantial losses. A revised schedule does not make a leveraged position safer, guarantee execution or remove the need to manage position size and risk.
14. Common Misunderstandings
Misunderstanding 1: CAS and expiry settlement are the same
They are different. CAS is a closing-price discovery process for eligible cash-market securities. Expiry settlement is a separate calculation for derivatives contracts.
Misunderstanding 2: All F&O contracts stop at the same time
The framework distinguishes expiring index derivatives from stock derivatives. Always check the contract type and expiry status.
Misunderstanding 3: VWAP guarantees a fair or profitable outcome
VWAP is a calculation method, not a guarantee. The official rules determine which trades and time periods are included.
Misunderstanding 4: Every open order will move into CAS automatically
Order-transition rules have eligibility conditions and exclusions. Do not assume every order carries forward unchanged.
Misunderstanding 5: The new rules guarantee lower risk
Market-structure changes do not guarantee trading performance. Liquidity, execution, price movements and position size still matter.
15. Important Dates to Remember
- October 15, 2026: SEBI issued the revised framework.
- December 7, 2026: Scheduled implementation date for most of the changes described in the framework.
- February 8, 2027: Scheduled implementation date for specified unexecuted limit and iceberg order-transition provisions.
These are the dates described in the announced framework. Check for subsequent circulars or clarifications before relying on them operationally.
Frequently Asked Questions
What are the revised SEBI market timings for 2026?
The framework includes a 3:30 PM to 3:40 PM Closing Auction Session, a 3:50 PM to 4:00 PM post-close cash-market session and revised derivatives trading cut-offs. Most changes are scheduled to take effect on December 7, 2026.
When does CAS begin?
The revised Closing Auction Session is scheduled to begin at 3:30 PM and run until 3:40 PM.
When does trading stop for expiring index derivatives?
Trading in expiring index derivatives is scheduled to cease at 3:30 PM on expiry day. Check the specific contract and current exchange instructions.
When do stock derivatives stop trading?
Stock derivatives are scheduled to trade until 3:45 PM, including on expiry days, under the revised framework.
What is the 30-minute VWAP settlement method?
It is the prescribed volume-weighted average price methodology over the last 30 minutes of continuous trading for expiry settlement. Index and stock derivatives use their respective underlying-value calculations.
Is the CAS reference price also based on 30-minute VWAP?
No. The CAS reference price uses the prescribed VWAP of the final 15 minutes of continuous trading, while expiry settlement uses a separate 30-minute VWAP methodology.
When do the order-transition provisions start?
The specified provisions concerning eligible unexecuted limit and iceberg orders are scheduled to take effect on February 8, 2027.
Will these rules guarantee better trade execution?
No. The rules define a process and timings, but execution depends on eligible orders, liquidity, prices, exchange procedures and market conditions.
Official Sources and Further Reading
- SEBI official circulars listing — look for the October 15, 2026 circular titled "Review of certain aspects of the Closing Auction Session, market timings and settlement methodology for derivatives contracts."
- National Stock Exchange of India (NSE)
- BSE India
Final Takeaway
SEBI's revised framework introduces a 3:30 PM to 3:40 PM Closing Auction Session, different expiry-day cut-offs for index and stock derivatives, a 3:50 PM to 4:00 PM post-close cash-market session and a 30-minute VWAP methodology for derivatives expiry settlement.
Most changes are scheduled for December 7, 2026, while the specified order-transition provisions are scheduled for February 8, 2027. Traders should understand the distinction between the CAS reference price and the expiry settlement calculation, check contract-specific timings and review official exchange notices before acting.
Disclaimer: This article is for general educational and informational purposes only. It is not investment advice, a recommendation to buy or sell securities, or a guarantee of returns. Futures and options involve substantial risk and may not be suitable for every investor. Verify regulatory details with official SEBI and exchange publications before making trading decisions.
