When a stock undergoes a corporate action such as a stock split, the International Securities Identification Number (ISIN) of stock changes. BSE and NSE updates the ISIN on different timelines -

1. BSE on the ex-date.
2. NSE on the record date, which is 1 working day after the ex-date.

At Zerodha, we update the ISIN of your holdings as per the NSE’s schedule hence if you try to sell your holdings on the BSE on ex-date, the order will fail to execute because of the change in ISIN.

Therefore, we block the CNC sell orders for scrips in BSE on ex-date for the following product types -

Regular orders - Sell CNC will not be allowed on the ex-date

AMO orders - You will not be able to place AMO orders for stocks 1 day prior to the ex-date.

You’ll get the following rejection message and nudge when you place the order -

To prevent encountering this rejection message, you can place your sell order on NSE.

Note:

1. The rejection message will only be shown if the stock is listed on both the exchanges i.e NSE and BSE and not when it’s listed only on BSE.
2. To switch between exchanges while selling, please go through this article .