The expiry day war between the country’s top two stock exchanges has officially ended with the Securities and Exchange Board of India (SEBI) allowing a swap in their existing weekly derivatives expiry days. The regulator has assigned Tuesday as the expiry day for all weekly index derivatives contracts of the National Stock Exchange (NSE) and Thursday for BSE’s contracts.
SEBI conveyed its decision to the exchanges on Tuesday, based on applications received by June 15. Sources indicate that the Metropolitan Stock Exchange (MSE) has also been assigned Tuesday as its expiry day.
This move comes after SEBI directed exchanges to limit weekly index derivatives expiries to Tuesdays and Thursdays, asking them to submit their preferences by mid-June. The changes are widely seen as SEBI’s attempt to reduce expiry-day clustering and ensure a more orderly derivatives market.
For existing contracts, both NSE and BSE clarified that expiry dates will remain unchanged, except for long-dated index options, which will be realigned as per past practices. However, for new contracts, expiry days will shift from September 1 onwards. Until August 31, existing expiry dates will continue. Monthly contracts will now expire on the last Tuesday of the month.
Exchanges will not introduce any fresh weekly index futures contracts after July 1. SEBI will issue a detailed circular defining operational modalities in due course, the exchange circulars said.
Swap impact
The shift of NSE’s expiry day from Thursday to Tuesday is expected to help the exchange claw back market share from rival BSE, which had seen a surge in its index derivatives volumes since its previous shift to Tuesday expiry earlier this year. BSE’s share in index options rose to 12.6 per cent from 3.1 per cent a year ago, with premium turnover climbing to around 22 per cent now from 16 per cent in December 2024.
However, Goldman Sachs expects BSE’s market share in premium turnover to drop by 3-4 percentage points with its return to Thursday expiries—down to 18.8 percent from the current 22.2 percent.
BSE sources, however, said the decision was driven by market feedback and the desire to avoid concentration of expiry volumes on one day. “We do not expect any dent in derivatives volumes,” an exchange source said.
An official at a large domestic brokerage said the decision brings a “level playing field” and ends prolonged expiry day issue. “This swap is more positive for NSE, especially since traders could now manage weekend risk better by shifting positions earlier in the week.”
The shift could affect BSE’s turnover dynamics slightly, though the long-term impact may not be significant, said Trivesh D, COO at Tradejini. “While derivatives have put BSE back in the spotlight, sustaining this momentum will depend on liquidity strength, pace of innovation, and how effectively the exchange navigates short-term shifts in trading behaviour. BSE also has a unique advantage due to a bigger ticket size of Sensex in comparison to Nifty 50.”
Despite the recent dip, NSE still commands a dominant 90 per cent market share in derivatives. It had initially preferred a Monday expiry, but SEBI intervened to restrict options to just two days—Tuesday and Thursday. Income from derivatives trading makes up a large part of the revenue for both stock exchanges. Going forward, any changes to expiry days by exchanges will require prior SEBI approval.
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Published on June 17, 2025