Chapter 9

The expiry machine

Published 30 September 2026

Every casino has a mechanism that determines how fast the money moves. In Indian F&O, that mechanism is the expiry: the weekly - briefly, daily - death and rebirth of the contracts everyone is trading. Understand the expiry machine and you understand why the losses compound so fast. Then watch what happened when the regulator finally touched it.

An index option is a bet with a clock. When the clock runs out, the bet settles, and every open position is closed at the settlement price - win, lose, or wipeout. For years, Indian exchanges competed to make the clock run faster: weekly expiries on every major index, staggered so that some contract, somewhere, expired nearly every trading day. Moneycontrol's account of the October 2024 crackdown describes the end state of that race: daily expiries across exchanges and indices, a perpetual motion machine of settlement days. Every day was expiry day somewhere. Every day was a fresh lottery drawing, with fresh premiums, fresh hope, and fresh losses.

Why the house loves a fast clock

The short-dated option is the purest gambling instrument ever listed on an exchange. It is cheap - a few thousand rupees buys a position. It is binary in feel - double or zero by Thursday. And it decays: time value bleeds out of it by the hour, so the buyer must be right about direction, magnitude and timing all at once, while the seller - usually the algorithm on the other side - simply harvests the decay. The regulator's own data says 91.5% of options traders lost in FY24, and the losses skew to exactly these short-dated contracts. Speed the clock up and you do not change the odds. You change the frequency. The same 91% loss rate, run four times as often, is a four-times-faster transfer.

That is the machine the exchanges built - each exchange chasing expiry-day volumes, because volumes are transaction fees, and transaction fees are the exchange's revenue. Every extra weekly expiry was a new revenue stream for the venue and a new recruitment surface for the brokers. The design was not an accident. It was a competitive arms race, and the crowd paid for both sides of it.

October 1, 2024: the regulator reaches in

Then SEBI touched the machine. The October 1, 2024 circular - "Measures to Strengthen Equity Index Derivatives Framework for Increased Investor Protection and Market Stability" - restructured the product itself, phased in from November 20, 2024. The headline measures, as Reuters reported them: minimum contract size hiked - roughly tripled, from ₹5 lakh to ₹15 lakh of underlying value; each exchange restricted to weekly expiries on only one benchmark index - the daily-expiry machine, unplugged; and upfront collection of the option premium from buyers, mandated in the circular's own words "in order to avoid any undue intraday leverage to the end-client".

Read those three moves as a diagnosis. Tripling the contract size prices the smallest players out of the deepest end. One weekly expiry per exchange kills the daily lottery. Upfront premium kills the intra-day free ride - you must actually have the money you are betting. Every measure is aimed at a specific way the machine was juicing velocity. The regulator could not say "this product is a casino" - it said, instead, in the circular's title, "investor protection and market stability", and then defunded the casino's busiest floor.

Six levers, one direction

The circular did not stop at the three headline moves. The Hindu BusinessLine counts six changes, rolled out in phases from November 20 - including tighter margin requirements around expiry day, where the wildest bets used to concentrate. Every lever pulled in the same direction: make the fastest, cheapest, most addictive corner of the market slower, bigger and more expensive to enter. Not banned. Never banned. Just priced, sized and timed so that the youngest, poorest recruit - the 43% under 30, the 76% earning under ₹5 lakh a year - has to step over a higher sill before he can lose his first ₹46,000.

That restraint is the most honest thing in the whole episode. The regulator looked at its own study - 93% losers, ₹1.81 lakh crore gone, recruitment skewing young and poor - and responded not with prohibition but with friction. Bigger contracts. Fewer expiries. Cash up front. Higher margins on expiry day. The casino stays open. The doors just got heavier. Whether friction is enough is the open question the next few years of data will answer; the first answers, from the brokers' own earnings, are that order flow fell by a fifth and the crowd began, slowly, to thin.

The machine's response

The industry's reaction told you what the machine was worth. Trading volumes fell hard in the following quarters - one large listed broker's orders dropped over 22% in a single quarter. Analysts wrote about "normalization". And within months, the debate had shifted to whether the tightening had gone too far - whether liquidity had been harmed, whether India was losing its derivatives crown. Notice what is never debated: whether the pre-October machine - the daily expiries, the ₹5 lakh contracts, the intraday leverage - was defensible in a market where the regulator's own study showed nine in ten humans losing. The machine had its defenders, and none of them were the people losing ₹2 lakh each.

The expiry machine still runs. Weekly contracts on Nifty and Bank Nifty remain the busiest derivatives on earth by volume. The regulator slowed the clock; it did not stop it. The next time you see a headline about record F&O volumes, translate it: the machine is running at speed again, and the seats are full.