SEBI Puts an End to Expiry-Day Confusion: What It Means for Markets and Traders

In a major regulatory move aimed at streamlining equity derivatives trading in India, the Securities and Exchange Board of India (SEBI) has approved a significant reshuffle of weekly expiry days across the country’s two biggest stock exchanges. Effective September 1, 2025, the National Stock Exchange (NSE) will transition its equity derivatives expiry to Tuesday, while the Bombay Stock Exchange (BSE) will switch to Thursday

Why this shift?

SEBI’s directive stems from a circular issued in late May 2025, mandating that all equity derivative contracts—including weekly, monthly, and longer tenors—must expire only on Tuesdays or Thursdays. The primary goals are:

• Mitigating market volatility caused by overlapping expiry days across exchanges.
• Reducing speculative frenzy by eliminating expiry-day arbitrage opportunities.
• Enhancing clarity and structural discipline in scheduling, thereby improving investor protection.

What’s changing—and when?

• Contracts expiring on or before August 31, 2025 will maintain the current schedule: NSE on Thursday, BSE on Tuesday.
• From September 1, 2025, all new and rolling equity derivatives contracts will follow the new schedule—Tuesday for NSE, Thursday for BSE.
• Notably, long-dated index options may be realigned to fit the new expiry framework.
• To accommodate this transition, BSE will cease introducing new weekly index futures contracts from July 1, 2025.

Implications for traders and exchanges

NSE gains tactical edge

With expiry now landing on Tuesday, traders on NSE benefit from an extra trading day—Friday, Monday, and Tuesday—to adjust or hedge positions. This “theta-play” window allows for strategic maneuvering ahead of expiration.

BSE navigates a tighter window

BSE’s new schedule offers just two sessions—Wednesday and Thursday—which may make it harder to attract traders. Analysts anticipate possible volume erosion of 10–15%, translating into a 5–10% hit to earnings.

To fortify liquidity, BSE plans to ramp up infrastructure—such as colocation racks—and onboard more brokers and foreign portfolio investors (FPIs).

Broader market impact

• Expiry arbitrage eliminated: Staggering NSE and BSE expiries levels the playing field and reduces arbitrage opportunities.
• Simplified trading calendar: A cleaner, more predictable expiry rhythm aids risk assessment and hedging strategies.
• Improved volatility monitoring: With expiry days clustered, SEBI can better monitor and manage market fluctuations around these critical periods.

What investors and market participants need to know

1. Mark your calendars: September 1, 2025, is the turning point.
2. Adjust strategies: NSE now offers more time pre-expiry; BSE’s window tightens—time your rollovers and hedges accordingly.
3. Watch for BSE developments: Improved infrastructure might offset the compressed expiry window.
4. Focus shifts to value and service: With timing standardized, competition between exchanges may increasingly revolve around liquidity, technology, and brokers’ efficiency.

Conclusion

SEBI’s expiry-day realignment represents a pivotal step toward greater structure and stability in India's derivatives market. By assigning discrete expiry days—Tuesday to NSE, Thursday to BSE—regulators aim to eliminate confusion, limit speculation, and bolster investor confidence.

For traders and market operators, this doesn’t just mean a calendar update—it’s a call to actively revisit strategies, plan for new timelines, and adapt to a market that’s becoming cleaner, smarter, and more regulated.