The National Stock Exchange has received regulatory approval to move its Nifty options weekly expiry from Thursday to Tuesday, providing an opportunity to regain market share lost to BSE Ltd. Earlier this year, BSE had shifted its Sensex options expiry to Tuesday from Friday, but has now decided to move it to Thursday, as per a notice from the exchange citing communication with Sebi.

Sebi's circular on 26 May mandates 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 formally requested the regulator to shift its Nifty weekly options expiry to Tuesday, which was approved by Sebi via email. NSE outlined a phased transition in a circular released on Tuesday.

Existing contracts will maintain their current expiry day (Thursday), except for long-dated index options, which will be realigned as per market practice. New contracts expiring on or before 31 August 2025 will continue to expire on Thursdays, while those expiring on or after 1 September 2025 will shift to Tuesday expiries. Monthly contracts will expire on the last Tuesday of the month starting 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 current Tuesday expiry, while those expiring on or after 1 September 2025 will move to a Thursday expiry. Monthly contracts from September onwards will expire on the last Thursday of the month.

Furthermore, no new weekly contracts on index futures will be introduced from 1 July 2025 onwards. Sebi's circular also requires exchanges to seek prior approval for any future changes in expiry days and update their systems and bylaws accordingly.

Weekly options trading is a crucial business for exchanges, with transaction charges contributing significantly to revenue. NSE's standalone revenue of ₹5,860 crore in the last quarter of the previous fiscal saw transaction charges making up half of it. Equity options accounted for 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, increasing its market share to 12.6% in the April–June 2025 period from just 3.1% a year earlier. On the other hand, NSE's market share of equity options based on premium turnover dropped to 80% as of the end of April, down from 92.8% a year ago.

Analysts believe NSE's move to Tuesday could potentially help it regain up to 5% market share in index options, posing a challenge to BSE's recent gains. With BSE-listed options seeing volumes spread across Friday, Monday, and Tuesday, a shift to Thursday could impact liquidity by compressing activity to Wednesday and Thursday.

Dinesh Thakkar, Chairman & MD of Angel One, noted, "Earlier, BSE had an extra day of volume accretion, now NSE will get that. This will boost NSE's premium turnover and transaction fees, ultimately enhancing its standalone revenue." NSE maintains dominance in the derivatives segment, holding over 75% share across both index and stock options, while BSE's share in index options has been steadily increasing.

Rajesh Palviya, Head of Derivatives and Technical Research at Axis Securities, commented, "NSE could potentially regain around 90% market share on Friday from around 75% due to the shift to Tuesday starting September 1." BSE closed down 1.2% at ₹2,664.40 on Tuesday, while the benchmark Sensex ended 0.3% lower.