Pin Risk
Quick Definition
The risk that a stock closes exactly at or very near an option's strike price at expiration, creating uncertainty about whether the option will be exercised.
What Is Pin Risk?
Pin risk occurs when the underlying asset's price is very close to an option's strike price as expiration approaches. This creates uncertainty for short option holders who don't know whether they will be assigned. If a short call is exactly at the money at expiration, the seller doesn't know if the counterparty will exercise until after the close — leaving them uncertain about their stock position over the weekend. Pin risk is most dangerous with spread positions: if only one leg is exercised (the short ITM leg) while the other expires worthless (the short OTM leg), the trader can end up with an unintended directional stock position. The phenomenon of stocks "pinning" to strikes with heavy open interest near expiration is well-documented and attributed to market maker delta-hedging activities.
Pin Risk Example
- 1A trader is short a $100/$105 call spread. At expiration, the stock is at $100.05 — the short $100 call might be assigned while the long $105 call expires worthless, leaving an unexpected short stock position
- 2SPY has massive open interest at the $450 strike. On expiration Friday, the stock trades between $449.50 and $450.50 all day, "pinned" by market maker hedging
Related Terms
Options Assignment
The process by which an option seller is obligated to fulfill the terms of the contract when the buyer exercises their right.
Open Interest
The total number of outstanding derivative contracts that have not been settled, closed, or expired, indicating market participation and liquidity.
Expiration Date (Options)
The last date on which an option contract can be exercised or traded, after which it becomes worthless if not in the money.
Strike Price
The predetermined price at which the holder of an option can buy (call) or sell (put) the underlying asset upon exercise.
Delta Hedging
A strategy that offsets the directional risk of an options position by trading the underlying asset in proportion to the option's delta.
Call Option
A contract giving the holder the right, but not the obligation, to buy an underlying asset at a specified price within a specified time period.
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