Options traders in India who have watched NIFTY or BANKNIFTY near expiry have likely noticed something odd: the index seems to get stuck near certain levels. It moves toward them, hovers, retreats, and comes back. This is not random. It is what happens when large open interest concentrations at a strike start influencing the behaviour of everyone hedging around it. That gravitational pull is called option pinning. The risk it creates for traders holding positions near those strikes at expiry is called pin risk.
Why prices cluster around certain strikes
When both call and put open interest are heavily concentrated at the same strike, market makers and institutional traders are continuously hedging their exposure around that level. To stay delta neutral, they buy and sell the underlying as the price moves toward or away from that strike. That hedging activity itself pushes the price back toward the strike. The more participants doing this, the stronger the effect.
On expiry day, even small price moves have large consequences for settlement. The hedging becomes more intense, and the clustering more pronounced.
| Expiry month | NIFTY close | Largest OI strike | Distance to strike |
| March 2025 | 21,750 | 21,700 | 50 points |
| April 2025 | 22,100 | 22,100 | 0 points |
| May 2025 | 22,250 | 22,200 | 50 points |
What pin risk actually means for traders
Pin risk arises when the underlying closes very close to a strike at expiry. At that point, it becomes genuinely unclear whether an option will be exercised or expire worthless. A difference of a few paise determines the outcome.
For option writers, that ambiguity creates real problems. If the underlying closes just in-the-money, the seller may be assigned and find themselves unexpectedly holding or shorting the underlying after settlement. If it closes just out-of-the-money, the option expires, and they keep the premium. The outcome can hinge on closing auction prices or after-market trades, neither of which the trader controls.
This is particularly relevant in NIFTY, BANKNIFTY, and liquid large-cap stocks, where open interest concentrations are large enough to matter.
Detecting pin risk zones from option chain data
When call and put open interest both spike at the same strike, that strike becomes a potential magnet. Consider a stock trading at ₹1,250 near expiry with 8 lakh contracts in open interest on the 1,250 Call and 7.5 lakh on the 1,250 Put. As expiry approaches, participants continuously adjust hedges and unwind positions around that level. The price range narrows. That narrowing is the formation of the pin risk zone.
Watching how open interest shifts in the final two to three days before expiry, not just where it sits, gives a clearer picture of where pinning is likely.
Common misconceptions
Pinning is often misread, even by experienced traders.
It is not manipulation. Most pinning comes from rational, risk-neutral hedging by dealers and market makers. The clustering is an emergent result of many participants doing similar things, not coordinated price control.
It does not only affect sellers. Option buyers can also face unexpected outcomes from late exercises or non-standard settlement, particularly in cash-settled contracts.
It does not happen every expiry. The effect requires high liquidity and concentrated open interest. Thinly traded instruments rarely show any meaningful pinning.
Strategies traders use around pin risk
Gamma scalping is one approach. As the price oscillates near a high open interest strike, traders continuously adjust delta exposure to capture small gains from the movement. It requires active management but can offset some of the unpredictability that pinning creates.
Large short straddle or strangle positions often need to be unwound before expiry. That unwinding generates its own buying or selling pressure, which can amplify the pinning effect. Traders who understand this can time their own exits to avoid the worst of the liquidity squeeze.
Box spreads are used by some professional traders to neutralise pin risk entirely, combining calls and puts across strikes to lock in a fixed payoff regardless of where the underlying settles.
For retail traders specifically
The strategies above require significant capital and execution capability. For most retail participants, managing pin risk is more about awareness than sophistication.
Watch which strikes carry the highest open interest as expiry approaches. Sudden spikes in OI at a level that is close to the current price are worth noting. Short positions at or near the money in the final session carry the highest assignment risk and are worth closing or hedging if assignment would create a problem.
Limit orders matter more on expiry day than at any other time. Volatility around key strikes can be erratic, and market orders during that session can result in poor fills. Post-market prices also deserve attention: closing auction trades can shift whether an option finishes in or out of the money.
Conclusion
Pin risk is a natural feature of how options markets work near expiry, not an anomaly. It comes from the concentration of open interest, the hedging behaviour that concentration drives, and the very thin line between exercise and expiry when price settles near a strike.
For traders who understand the mechanics, it is a manageable risk. For those who do not, expiry day occasionally produces surprises that are entirely explainable in hindsight.
