SEBI asks brokers to take orders in 3:15-3:20 CAS window

What SEBI has asked brokers to change

SEBI has asked stockbrokers to accept client orders during the five-minute transition window from 3:15 pm to 3:20 pm, according to people cited by Reuters and Mint. This window sits right at the start of the Closing Auction Session (CAS), which is used to determine the market close for stocks. Under the current setup, brokers do not take orders in those five minutes. The regulator’s intent, as described by sources, is to improve liquidity and price discovery around the close. Three brokers told Reuters that the request is meant to improve participation under the new closing mechanism. Mint also reported that SEBI has asked brokers to update their systems to enable order acceptance in those initial minutes. The operational change being discussed is specific to order acceptance at broker platforms during the transition phase. The broader goal is to prevent potential investor demand from remaining outside the closing auction just because of the five-minute pause.

How the Closing Auction Session works today

CAS is described as a 20-minute auction window that begins at 3:15 pm IST after regular trading ends. It runs until 3:35 pm and is used to determine the closing levels of stocks, with Reuters noting its role in determining closing levels. The first five minutes, from 3:15 pm to 3:20 pm, are currently treated as a transition period. During this period, the system calculates a reference price and shifts from continuous trading to the auction framework. Under the present mechanism, fresh orders are not accepted from 3:15 pm to 3:20 pm, as stated in the reports. Only after 3:20 pm does the order entry phase begin under the existing setup. That structure has meant that investor orders placed during the initial five minutes cannot be entered into CAS at that moment. The change under discussion targets this operational gap.

Why the 3:15-3:20 pm window matters

The five-minute period is important because it sits immediately after continuous trading ends, when many investors react to end-of-day moves. Sources told Reuters the change is designed to improve liquidity and price discovery under the closing mechanism. Price discovery at the close matters because the closing price is widely tracked and used as a reference by market participants. When orders cannot be accepted during 3:15 pm to 3:20 pm, some trading interest may be deferred or missed for the closing auction. The regulator’s thinking, as described by people aware of discussions, is that accepting orders in this window could increase participation in CAS. It also addresses a practical friction point on broker apps and websites during the transition phase. Reports also indicate the intention is to improve efficient price discovery, not to extend continuous trading. The focus remains on how orders enter the auction once the order-entry period begins.

Current vs proposed process at a glance

The public discussion so far, as reported by Reuters, Mint, and other outlets, points to a workflow change for brokers rather than a change in the CAS timing itself. The CAS still starts at 3:15 pm and ends at 3:35 pm, and the five-minute transition remains tied to reference price calculation. What changes is whether brokers can accept orders during those five minutes and then route them into CAS once order entry opens. NDTV Profit sources said brokers may accept client orders from 3:15 pm to 3:20 pm and push them to the market after 3:20 pm. Zee Business sources similarly said orders received as AMOs between 3:15 pm and 3:20 pm could be pushed into CAS after the auction order-entry process begins. This is positioned as a way to ensure orders placed during the transition do not stay outside the closing auction. The reports do not describe changes to the reference price calculation itself. They instead highlight the broker-side order capture during the transition window.

After-market orders and how routing may work

Several reports frame the change in terms of after-market orders (AMOs) during the 3:15 pm to 3:20 pm period. NDTV Profit sources said these orders would be accepted by brokers during the transition window and then pushed into the market after 3:20 pm when CAS order entry begins. Zee Business sources echoed a similar structure, focusing on broker platform alignment and routing once the auction order-entry opens. This approach aims to reduce the chance that an investor placing an order just after 3:15 pm has to wait for the next trading session for processing. It also suggests that broker systems must distinguish between accepting the order and sending it to the exchange at the right time. The reporting indicates SEBI has asked brokers to align their apps and websites to support the new flow. Importantly, the sources describe an operational routing change rather than immediate matching during the transition minutes. The five-minute period still exists as a transition, but the investor-facing experience could shift if brokers accept orders in that slot.

What brokers are saying publicly so far

A clear on-record comment in the reporting comes from HDFC Securities. Dhiraj Relli, managing director and CEO at HDFC Securities, was quoted as saying: “Starting September, we will begin accepting aftermarket orders between 3:15 and 3:20 pm.” He added that the move is expected to improve price discovery and liquidity in CAS, according to Mint. Reuters also reported that SEBI has asked brokers to accept orders during the five-minute transition to improve liquidity and price discovery, citing three brokers. The reports indicate that brokers are being asked to update their systems to make this possible. This implies technology and operational changes across broker platforms, including order capture and exchange routing logic. The same theme appears across multiple outlets: accept orders during the transition, but route them into CAS once the order-entry phase begins. No report in the provided context specifies penalties or enforcement details, focusing instead on the directive and expected implementation. The public quotes and source comments point to September as the operational start period.

Timeline and rollout signals investors should note

Multiple sources indicate the change is being prepared for September. Reuters-linked social posts and other sources suggest implementation could begin around September 1, though the reporting frames this as expected timing rather than a final confirmed date. Zee Business sources said the changes are expected to be reflected on broker platforms after September 1, with rollout soon thereafter. Mint’s reporting, via people aware of the development, also points to September as the start window. In practical terms, investors may see broker apps begin to accept orders during the 3:15 pm to 3:20 pm window that previously rejected or deferred them. The transition could be visible as a new order type, a revised AMO cut-off, or a different validation rule on broker platforms, depending on the broker. The context provided does not describe a uniform interface standard, only that brokers have been asked to update systems. Investors should therefore expect broker-by-broker variations in how the change is displayed. The core common element is timing: order acceptance in those five minutes, with routing to CAS after 3:20 pm.

What this could mean for end-of-day traders

For traders focused on the closing price, the reported change could expand the window to place orders intended for the close. If more orders get captured and routed into CAS, the auction could see higher participation, which is what the sources say SEBI is aiming for. This is particularly relevant because CAS is specifically used to determine the closing levels of stocks, and Reuters notes it is used for closing levels under the new mechanism. The reports also reference CAS determining closing levels of F&O stocks through order matching, highlighting the importance of the close in those names. However, investors should not assume guaranteed execution, because an auction mechanism matches orders based on available interest and pricing conditions. The reporting only states that brokers will accept orders during 3:15 pm to 3:20 pm and route them after 3:20 pm, not that fills will improve for every order. The first five minutes still remain dedicated to reference price calculation and transition, so the market structure timing is still segmented. As brokers roll out changes, investors may need to check broker-specific cut-offs and how AMO orders are labeled during that interval. The main practical impact is reduced friction in placing an order intended for participation in CAS shortly after 3:15 pm.