SEBI Regulates Expiry Day Clash Between NSE and BSE

The Securities and Exchange Board of India (SEBI) has approved a significant change in the weekly expiry cycle for equity derivatives across India’s top stock exchanges. Starting September 1, 2025, the National Stock Exchange (NSE) will shift its weekly options and futures expiry from Thursday to Tuesday, while the Bombay Stock Exchange (BSE) will adopt Thursday expiry instead.

This move follows a SEBI circular from May 26, which required exchanges to choose one of two fixed expiry days - Tuesday or Thursday - for their benchmark index and equity derivative contracts, aiming to streamline the market and reduce volatility.

Why is SEBI bringing the change between expiry days of NSE and BSE

There are mainly two reasons for the current change:

Reduce Volatility & Speculative Frenzy: Previously, multiple expiry days led to fragmented and heightened volatility around expiry periods. Consolidating to just two days enhances predictability and aids investor protection.
Market Stability & Fair Access: With all big players tied to fixed, staggered expiries, the risk of overlapping and scrambling markets is curbed. This is part of SEBI’s broader strategy to safeguard market integrity.

When are the expiry day changes getting implemented?

Here are crucial dates traders must make a note of:

Before Sep 1, 2025: Existing contracts continue with their original expiry schedules—NSE on Thursdays, BSE on Tuesdays; long-dated index options will be realigned.
From Sep 1, 2025:

NSE: Weekly/monthly equity derivative contracts expire every Tuesday
BSE: Corresponding contracts expire every Thursday

What does the change in expiry days of NSE and BSE mean for traders?

The new changes will have an impact both on traders and exchanges. Let us look at the details:

NSE’s Tuesday Edge: With trading sessions on Friday, Monday, and Tuesday, traders gain an extra session to strategize and offset positions before expiry. This “theta-play” advantage is notably stronger on NSE.
BSE’s Narrow Window: BSE’s Thursday expiry offers only two sessions—Wednesday-Friday are grouped post-NSE expiry—making it tougher to attract traders

What does the change in expiry days of NSE and BSE mean for exchanges?

Here are a few notable impacts (positive and negative) for the exchanges:

NSE stands to gain market share, appealing to traders preferring longer cycles.
BSE may lose share, with analysts cautioning a potential 10–15% volume drop, translating to a 5–10% earnings hit.
BSE Strategy: Plans to enhance liquidity through increased co-location racks and improved broker/FPIs on-boarding—says MD & CEO Sundararaman Ramamurthy.

What will be the broader market impact?

Here are some broader market impacts:

Expiry Arbitrage Diminished: Traders can no longer exploit staggered BSE/NSE expiries (e.g., buying in one, selling in another). This levels the playing field.
Cleaner Trading Calendar: One expiry day per exchange reduces clutter and aids in systematic risk assessment and hedging.
Monitored Volatility: Fewer expiry days help SEBI track and moderate spikes during these sensitive periods.

Before you go

This regulatory overhaul by SEBI marks a major shift in India’s derivatives landscape. The move seeks to boost stability, enhance investor protection, and clean up speculative activity by fixing staggered expiry days. With its new Tuesday expiry, NSE gains a tactical advantage, while BSE faces the challenge of maintaining volume within a compressed cycle.

Both exchanges will hence compete more intensely on liquidity, technology, and broader ecosystem support, rather than on timing.