Mumbai: The National Stock Exchange is set to shift its weekly expiry for Nifty options from Thursday to Tuesday after getting the regulatory approval, giving it an opportunity to claw back share lost to rival BSE Ltd.

BSE, which had moved its Sensex options expiry to Tuesday from Friday earlier this year, has opted to shift it to Thursday, the exchange said in a notice citing communication with the Securities and Exchange Board of India (Sebi).

Sebi’s 26 May circular requires stock exchanges to designate a single expiry day—either Tuesday or Thursday—for all equity derivative contracts, including weekly, monthly, quarterly and semi-annual expiries.

NSE submitted a formal request to the regulator to move its Nifty weekly options expiry to Tuesday. Sebi has since communicated its approval via email, which NSE confirmed and outlined a phased transition in a circular released on Tuesday.

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Existing contracts will retain their current expiry day (Thursday), except for long-dated index options, which will be realigned per standard market practice, said the exchange in the circular.

New contracts expiring on or before 31 August 2025 will continue to expire on Thursdays.

Contracts expiring on or after 1 September 2025 will shift to Tuesday expiries. Monthly contracts will expire on the last Tuesday of the month from that date.

Similarly, BSE’s existing contracts will retain their expiry days, except for long-dated index options.

Contracts expiring on or before 31 August 2025 will continue with the existing Tuesday expiry.

Contracts expiring on or after 1 September 2025 will move to a Thursday expiry. Monthly contracts, starting September, will expire on the last Thursday of the month.

In addition, no fresh weekly contracts on index futures will be introduced from 1 July 2025 onward.

Sebi’s circular also mandates that exchanges obtain prior approval for any future changes in expiry days and update their systems and bylaws accordingly.

Volume game

Weekly options trading is a key business for an exchange. Transaction charges contributed half of NSE’s standalone revenue of ₹5,860 crore in the last quarter of the previous fiscal.

Equity options contributed close to 76% of the ₹2,939 crore transaction charges, with cash and equity futures contributing the rest.

BSE’s earlier shift to Tuesday helped it gain traction in index derivatives, with its market share rising to 12.6% in the April–June 2025 period from just 3.1% a year earlier, according to data reviewed by Mint.

NSE’s market share of equity options based on premium turnover was 80% as of the end of April, down from 92.8% a year ago, according to the bourse’s data.

Analysts say NSE’s move to Tuesday could help it claw back up to 5% market share in index options, potentially eroding BSE’s recent gains. Under the current setup, BSE-listed options see volumes spread across Friday, Monday and Tuesday. A shift to Thursday would compress activity to Wednesday and Thursday, possibly affecting liquidity.

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“Earlier, BSE had an extra day of volume accretion, now NSE will get that,” said Dinesh Thakkar, chairman & MD, Angel One.” This will add to NSE’s premium turnover and give a leg up to its transaction fees, in turn boosting its standalone revenue.”

NSE continues to dominate the derivatives segment, with over 75% share across both index and stock options. BSE’s share in index options, however, has steadily grown—from 11.3% during April–September 2024 to 19.4% between October 2024 and June 2025.

NSE had earlier planned to move all expiries to Monday from 4 April but deferred the plan pending regulatory clarity. With the Sebi circular now in place and both exchanges having finalized their expiry days, implementation of the revised framework is set to begin later this year.