Pin Risk
The risk when a stock closes at or near your short option's strike at expiration.
Pin risk occurs when a stock's price closes very near a short option's strike price at expiration. When the stock is right at the strike, you do not know whether your short option will be exercised or expire worthless. You might end up with an unexpected stock position, or not — and you will not find out until after the market closes. This uncertainty creates risk that is difficult to hedge and can result in unintended positions that are exposed to weekend gap risk.
Why It Matters
Pin risk is one of the most commonly misunderstood risks in options trading. New traders assume that expiration is straightforward: either your option is in the money (exercised) or out of the money (expires worthless). But when the stock closes within pennies of the strike price, the outcome becomes unpredictable. Some option holders exercise, others do not. You might be assigned on some of your short contracts but not all of them.
The real danger comes after the assignment. If you are assigned on a short call Friday evening, you now hold a short stock position over the weekend. If positive news hits over the weekend, the stock gaps up Monday morning and your short stock position generates a significant loss. You did not intend to take this position — the pin created it.
How It Works
Why stocks "pin" to strikes: Stocks often gravitate toward heavy open interest strikes near expiration. This happens because of delta hedging by market makers. When there is heavy open interest at a strike, market makers who sold those options need to delta-hedge. As expiration approaches, their hedging activity (buying as the stock dips below the strike, selling as it rises above) acts as a magnet that keeps the stock near the strike.
The timeline of pin risk:
- Friday, 3:59 PM: Stock closes at $100.02 — your short $100 call is barely in the money.
- Friday, 4:00 PM: Market closes. You cannot trade options anymore.
- Friday, 5:30 PM: The OCC determines which options are exercised. Your short call is auto-exercised because it is $0.02 ITM.
- Saturday: You now own a short stock position of 100 shares per contract. You cannot do anything about it until Monday.
- Monday, 9:30 AM: If the stock gaps up $3, your short position just lost $300 per contract. If it gaps down, you profit — but you did not choose to take this bet.
Pin risk with spreads: Pin risk is worse with spreads because only one leg might get assigned while the other expires worthless. Example: You have a $100/$105 call spread. The stock closes at $100.15. Your short $100 call is assigned (you are now short stock), but your long $105 call expires worthless (it was out of the money). You are now naked short stock over the weekend.
How to manage pin risk:
- Close positions before expiration. The simplest solution. If your short option is anywhere near the strike with one or two days to go, close it. The small cost of closing is worth avoiding the uncertainty.
- Close by 3:00 PM on expiration day. Do not wait until the last minute. Liquidity deteriorates and spreads widen near the close on expiration Friday.
- Monitor open interest. Heavy open interest at your short strike increases pin risk because the stock is more likely to gravitate there.
- Use cash-settled index options (SPX). No shares change hands, so pin risk is eliminated. European-style settlement means no early assignment either.
- Be aware of after-hours movement. Even after the 4:00 PM close, stocks can move in after-hours trading. The OCC uses the after-hours price for auto-exercise decisions.
Quick Example
You sold a $150/$155 call spread on a stock that closes at $150.05 on expiration Friday. Your short $150 call is auto-exercised — you are now short 100 shares at $150. Your long $155 call expires worthless. Over the weekend, the company announces a positive earnings revision and the stock opens Monday at $153. Your short stock position loses $300. Had you closed the spread for $0.10 on Friday afternoon, you would have saved $290.