HO/47/11/11(3)2025-MRD-POD2/I/2765/2026

2 · 1. CAS aggregates market interest into a single pool of liquidity, thereby providing a fair and transparent closing price and improving the efficiency of execution for large orders.

2 · 2. The significance of a fair and transparent closing price , especially since it is used as the reference for settlement in derivatives, index computation, mutual fund net asset value (NAV) determination, etc .

2 · 3. Provides equal and transparent access to all categories of investors, ensuring that the discovered closing price reflects the collective market consensus at the close of trading hours .

2 · 4. Facilitates passive funds to transact at the closing price of the stocks thereby reducing the tracking error.

4 · 1. Applicability of CAS:

4 · 1.1. CAS shall be made applicable in a phased manner. Initially, the closing price of stocks in the cash segment on which derivative contracts are available shall be determined based on CAS.

4 · 1.2. The closing price for the remaining securities in the cash segment shall continue to be determined based on VWAP of the trades executed during the last 30 minutes of the CTS in the cash segment.

4 · 2. Timings of CAS:

4 · 2.1. CAS shall be implemented as a separate session of 20 minutes from 3:15 pm to 3:35 pm on all trading days, as under:

4 · 2.2. The order entry session shall close randomly anytime between 3:28 p.m. to 3:30 p.m . Such random closure shall be system driven.

4 · 2.3. The equity derivatives segment shall continue to operate up to 3:40 p . m. on all trading days.

4 · 2.4. The post close session in the cash segment shall operate between 3:50 p.m. to 4:00 p.m., where trades shall be executed at the closing price of stocks.

4 · 2.5. The closing price of stocks in the cash segment for trading in any special trading sessions of the Stock Exchanges shall also be determined based on CAS . The duration of CAS in such special

4 · 3. Reference Price for CAS:

4 · 3.1. The reference price of a stock in CAS in the cash segment shall be determined based on the VWAP of the trades executed in the stock during the period 3:00 p.m. to 3:15 p.m.

4 · 3.2. In case no trade is executed in a stock in the cash segment during the period 3:00 p.m. to 3:15 p.m. , t the Last Traded Price (LTP) of the stock during the day shall be taken as the reference price for CAS. In case there is no trade during the day, the closing price of the stock of the previous trading day shall be taken as the reference price for CAS. In case of corporate action, previous day's closing price shall be the adjustable closing price or the base price.

4 · 4. Applicable price band:

4 · 4.1. Price band applicable during CAS shall be +/- 3% from the reference price of the stock.

4 · 4.2. The price band of stock futures during the period from 3:15 p.m. to 3:40 p.m. shall be in alignment with the price band applicable during

4 · 4.3. The Stock Exchanges, within 30 days from the date of the circular , shall jointly formulate a Standard Operating Procedure (SOP), in consultation with SEBI, to ensure alignment of the price band of stock futures with the price band applicable during CAS.

4 · 5. Types of orders allowed in CAS:

4 · 5.1. Only limit orders and market orders shall be allowed and both shall be reckoned for computation of equilibrium price.

4 · 5.2. Iceberg orders shall not be allowed, i.e., orders shall be disclosed in full quantity.

4 · 5.3. Stop loss orders shall not be allowed.

4 · 6. Equilibrium Price Mechanism:

4 · 6.1. The closing price in CAS shall be determined based on the equilibrium price mechanism.

4 · 6.2. The equilibrium price shall be the price at which the maximum volume is executable.

4 · 6.3. In case more than one price meets the criteria as stated in para 4.6.2, the equilibrium price shall be the price at which there is minimum unmatched order quantity in terms of absolute value .

4 · 6.4. In case more than one price has same minimum unmatched order quantity, the equilibrium price shall be the price closest to the reference price.

4 · 6.5. In case the reference price is the mid-value of the pair of prices as mentioned in para 4.6.4 above, then the reference price itself shall be the closing price .

4 · 6.6. In case no equilibrium price is discovered , then reference price itself shall be the closing price.

4 · 7. Order execution priority in CAS:

4 · 7.1. Market orders shall be given priority over limit orders. The sequence for order execution shall be as under:

4 · 7.1.1. Eligible market orders shall be matched with eligible market orders in the order of time priority at the equilibrium price.

4 · 7.1.2. Residual eligible market orders, in the order of time priority, shall be matched with limit orders in the order of price time priority.

4 · 7.1.3. Remaining limit orders shall be matched with limit orders in the order of price time priority.

4 · 8. Unexecuted limit orders of the CTS:

4 · 8.1. All unexecuted limit orders of the CTS shall be carried forward to CAS , except the following:

4 · 8.1.1. Stop loss orders

4 · 8.1.2. Iceberg orders

4 · 8.1.3. Orders having prices beyond the price bands applicable in CAS .

4 · 8.2. The limit orders carried over from the CTS to CAS shall have a higher time priority than limit orders placed during CAS .

4 · 8.3. The limit orders carried over from the CTS to CAS can be modified , however, time priority after the modification shall be changed.

4 · 9. Calculation of settlement prices by Clearing Corporations (CCs) for stock derivatives and index derivatives:

4 · 9.1. Since, the methodology for computation of the closing price for stocks shall undergo a change, para 1.1.9 and para 3.1.2.7 of Chapter 5 of the Master Circular for Stock Exchanges and Clearing Corporations (SECC) dated December 30, 2024, shall be modified as follows:

4 · 9.2. The Stock Exchanges/ CCs shall jointly formulate a SOP, in consultation with SEBI, for determining the closing/ settlement prices for the stock derivatives and index derivatives , within 30 days from the circular .

4 · 10. The current risk management system for cash market shall be applicable during CAS.

4 · 11. Orders in CAS shall be subject to applicable margin requirement at order level , except for the limit orders carried over from CTS to CAS. However, if such limit orders are modified during CAS, then, such limit orders shall also be subject to applicable margin requirement at the order level.

4 · 12. The following information shall be disseminated during CAS:

4 · 12.1. Indicative equilibrium price of the stock

4 · 12.2. Indicative cumulative buy and sell quantity of the stock

4 · 12.3. Indicative imbalance quantity of the stock at equilibrium price

4 · 12.4. Indicative imbalance quantity based on market orders of the stock

4 · 12.5. Indicative Index

5 · Alignment of the Pre-Open Auction Session framework with CAS in the cash segment and the derivative segment:

5 · 1. To ensure alignment of the pre-open auction session with CAS, the relevant paragraphs with respect to 'Framework for the Call Auction in the Pre-Open Session' as specified under para 17.1 of Chapter 1 of the Master Circular for Stock Exchanges and Clearing Corporations (SECC) dated December 30, 2024 , shall stand modified as under:

17 · 1.3: The session shall close randomly during last 2 minutes of order entry period, i.e., anytime between 9:08 a.m. to 9:10 a.m. Such random closure shall be system driven.

17 · 1.4: Limit orders and market orders shall be entered during the pre-open session and both shall be reckoned for computation of equilibrium price. No iceberg order shall be allowed, i.e., orders shall be disclosed in full quantity. Further, no stop loss orders shall be allowed.

17 · 1.9. Market orders to be given priority over limit orders for execution in the pre-open session, as specified below:

17 · 1.9.1. Eligible market orders shall be matched with eligible market orders in the order of time priority at the final equilibrium price.

17 · 1.9.2. Residual eligible market orders, in the order of time priority, shall be matched with limit orders in the order of price time priority.

17 · 1.9.3. Remaining limit orders shall be matched with limit orders in the order of price time priority.

17 · 1.14. The following information shall be disseminated during preopen session:

17 · 1.14.1. Indicative equilibrium price of the stock

17 · 1.14.2. Indicative cumulative buy and sell quantity of the stock

17 · 1.14.3. Indicative imbalance quantity of the stock at equilibrium price

17 · 1.14.4. Indicative imbalance quantity based on market orders of the stock

17 · 1.14.5. Indicative Index

6 · Implementation timeline:

6 · 1. The framework for CAS outlined at para 4 shall be implemented in the cash segment from August 03, 2026 .

6 · 2. The changes in Pre-Open Auction Session framework outlined at para 5 , shall be implemented from September 07, 2026 .

6 · 3. Stock Exchanges/ CCs shall jointly formulate SOPs in terms of para 4.4.3 and 4.9.2 in consultation with SEBI within 30 days from the date of the circular.

9 · 1. Make necessary amendments to the relevant bye-laws, rules and regulations for the implementation of the above decision, as may be applicable.

9 · 2. Bring the provisions of this circular to the notice of the market participants and to disseminate the same on their website.