📉 The Problem: Expiry Day Madness
Every Tuesday and Thursday, the Indian stock market turns into a high-stakes game show. Why? It’s weekly expiry day — when options expire and retail traders pile in, chasing fast gains. The dream? Flip ₹10,000 into ₹1 lakh in a few hours using zero day to expiry (0DTE) options. No overnight risk. Just quick trades and adrenaline.
This trade has exploded. In 2019, retail traders made up just 27% of index options turnover. Today? Over 35%. Telegram groups buzz with strike levels like cricket scores. Apps make trading as easy as swiping right. Volumes have gone through the roof.
But here’s the kicker: most of these trades aren’t based on fundamentals. They’re momentum-driven, crowd-fueled, and often unhedged. And when they go wrong, they cause whiplash — not just in derivatives, but in the underlying cash market too.
That’s a red flag for SEBI. Because when speculation outpaces actual liquidity, it distorts price discovery — the very thing markets are meant to do.
⚖️ The Fix: SEBI’s New Rulebook
On May 29, SEBI dropped a detailed 21-page circular packed with sweeping changes to how India’s F&O market operates. Whether you’re a trader, a broker, or just curious — here’s what you need to know.
1. From Lots to Delta: Rethinking Risk
Right now, 1,000 lots of options and 1,000 lots of futures look the same on paper. But they’re not. Options behave differently depending on strike price, volatility, and time left. So SEBI wants to shift focus from lot sizes to delta.
Delta measures how much an option mimics the movement of the underlying asset. A future has a delta of 1. An out-of-the-money option may have just 0.2. SEBI’s solution? A new metric called Future Equivalent Open Interest (FutEq OI) — which converts option positions into futures-equivalent terms using delta.
Starting now, clearing houses must publish this data daily, making risk transparent and uniform.
2. Tightening the Ban Period Loopholes
Every stock in F&O has a Market-Wide Position Limit (MWPL). When open interest crosses 95%, it enters a ban. In theory, traders should stop building positions. In practice, they game it — switching sides, tweaking strategies, or using combos that keep exposure intact.
SEBI’s crackdown: once a stock hits the ban, traders must reduce their net delta exposure by the next trading day. No flipping sides, no clever hedges. You have to cut risk. This rule kicks in on October 1, 2025.
3. Smarter MWPL: Linked to Real Liquidity
Until now, MWPL allowed up to 20% of a stock’s free-float to be used for F&O. But some stocks hardly traded in the cash market, leading to outsized derivatives action.
SEBI’s new rule: MWPL will be the lower of:
- 15% of free-float shares, or
- 65× the average daily delivery value
With a minimum floor of 10%, this ensures that F&O action is grounded in real, deliverable liquidity. Effective October 1, 2025.
4. Caps on Index Speculation
SEBI is also setting hard limits on index-level speculation:
- Max ₹1,500 crore in net delta exposure across index options
- Max ₹10,000 crore in gross directional exposure (either long or short)
Starts July 1, 2025, with warnings first. Penalties begin December 6, 2025.
5. Pre-Open Session for Futures
To tame morning volatility, SEBI will introduce a pre-open session for futures — similar to the cash market’s 9:00–9:08 am window. It starts December 6, 2025, and will include next-month contracts during rollover weeks.
6. No More “Fake” Indices in F&O
New non-benchmark indices must follow strict criteria to qualify for F&O:
- At least 14 stocks
- No stock with more than 20% weight
- Top 3 combined weights under 45%
This prevents backdoor exposure via a single dominant stock. Live from November 3, 2025.
7. Tighter Position Limits for All
Retail traders, FPIs, mutual funds — everyone faces new caps on single-stock F&O positions, tied to the revised MWPL. For most retail clients, the limit is 10% of MWPL. Effective October 1, 2025.
🧠 What This Means for You
Let’s break it down by type of trader:
🔸 Retail Traders
- Delta knowledge is now mandatory.
- Expect brokers to add delta calculators, visual risk meters, and real-time alerts.
- Ignorance of position risk = penalties.
🔸 Option Writers
- Gross exposure caps mean splitting across strikes or expiries won’t help.
- Intraday strategies will need tight delta control and better hedging.
🔸 Arbitragers & Leverage Seekers
- Illiquid stocks will lose their F&O punch.
- The old “ban list rally” trade? Probably dead.
🔸 Algo Desks & Institutions
- Real-time delta tracking is now critical.
- No more waiting till EOD for risk assessment.
🔸 Offshore Migration?
High-risk expiry-day strategies might shift to other offshore platforms. Because speculation doesn’t end — it just moves.