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The tendency for a stock to gravitate toward strikes with heavy open interest as expiration approaches, driven by delta hedging flows.
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Key takeawayPin action is strongest 1-2 days before expiration on high-OI strikes. Factor it in when choosing expiration timing.
💡 Why It Matters
Pin action is the tendency for stocks to gravitate toward strikes with heavy open interest as expiration approaches. The mechanism is delta hedging: as options near expiration, market makers adjust hedges in ways that push the stock toward high-OI strikes.
⚙ How It Works
As an option approaches expiration, its gamma increases. At the high-OI strike, many gamma-rich options exist. Market makers delta-hedging these positions buy on dips below the strike and sell on rallies above it — creating a pinning effect. Strongest in the last 1-2 days before expiration.
📋 Example
SPY $580 has 120,000 OI (calls + puts). SPY $575 has 35,000 OI. As expiration approaches, dealer hedging at $580 creates a gravitational pull. SPY that was trading at $583 drifts down to $580-$581 by Thursday afternoon — classic pin action.
⚠ Common Mistakes
Treating pin action as guaranteed. It works best on calm weeks with concentrated OI. Events, earnings, and strong trends overwhelm pinning forces. Also: pin action shifts as OI changes — the pin target on Monday might be different from Thursday's pin target.
⚡ Pin Action in VolRadar
❓ FAQ
What is Pin Action?
The tendency for a stock to gravitate toward strikes with heavy open interest as expiration approaches, driven by delta hedging flows.
Why does Pin Action matter for premium sellers?
Pin action is strongest 1-2 days before expiration on high-OI strikes. Factor it in when choosing expiration timing.
How does Pin Action work?
As an option approaches expiration, its gamma increases. At the high-OI strike, many gamma-rich options exist. Market makers delta-hedging these positions buy on dips below the strike and sell on rallies above it — creating a pinning effect. Strongest in the last 1-2 days before expiration.
What are common mistakes with Pin Action?
Treating pin action as guaranteed. It works best on calm weeks with concentrated OI. Events, earnings, and strong trends overwhelm pinning forces. Also: pin action shifts as OI changes — the pin target on Monday might be different from Thursday's pin target.
Related Terms
0DTE
Options expiring on the current trading day — zero days to expiration.
Backwardation
When near-term VIX exceeds longer-term VIX (VIX/VIX3M ratio above 1.0).
Block Trade
A block trade is a privately negotiated options transaction of at least 50 contracts (varies by exchange) that is executed off the public order book and then...
Charm Exposure
The aggregate delta decay across all options in a dealer hedging book.
This is not financial advice. Read our full investment disclaimer.