Reading the option chain near expiry
The option chain tells a richer story near expiry. Open interest shifts, the put-call ratio swings, liquidity concentrates at round strikes, and gamma exposure reveals where dealer hedging may amplify or dampen moves. These pages teach you to read those signals — as information, never as tips.
Option Chain During Expiry: Near expiry the option chain shows open interest concentrating and unwinding at key strikes, a changing put-call ratio, migrating liquidity toward at-the-money and round strikes, and a gamma-exposure profile that indicates where dealer hedging may stabilise or destabilise price. These are analytical signals, not trade signals.
Open Interest Shift Near Expiry
Open interestOpen interest (OI) shift is the change in the number of outstanding option contracts at each strike on the chain as expiry approaches, with OI typica…
Put-Call Ratio (PCR)
Sentiment gaugePut-Call Ratio (PCR) is the ratio of total put activity to total call activity on the option chain — usually open interest, sometimes volume — used a…
Strike Migration Near Expiry
Strike dynamicsStrike migration is the way the at-the-money strike, and the trading focus, open interest and liquidity that cluster around it, shift to a different …
Liquidity Changes on the Chain
LiquidityLiquidity change is the way tradability — tight bid-ask spreads, market depth and ease of execution — concentrates at at-the-money and round-number s…
Volume Changes Near Expiry
ActivityVolume change is the shift in how many contracts trade at each strike per session, which typically surges overall and concentrates around at-the-mone…
Gamma Exposure (GEX)
Dealer hedgingGamma Exposure (GEX) is an estimate of the aggregate gamma that dealers and market-makers are net holding across the option chain, used to gauge whet…
Dealer Positioning Concepts
Dealer hedgingDealer positioning refers to the aggregate hedging exposure that market-makers and large dealers accumulate as the counterparty to public option orde…
Frequently asked questions
What does open interest tell you near expiry?
Open interest shows how many contracts are still outstanding at each strike. Near expiry, large OI at a strike marks a level many participants care about (often a max-pain or support/resistance zone), and the way OI builds or unwinds hints at whether positions are being added or closed.
What is gamma exposure (GEX)?
Gamma exposure estimates the aggregate gamma that option market-makers are hedging. When dealers are net long gamma they hedge against the trend (dampening moves); when net short gamma they hedge with the trend (amplifying moves). It helps explain why some expiry days are calm and others violent.
What is the put-call ratio?
The put-call ratio (PCR) compares put activity to call activity, by volume or open interest. It is used as a rough sentiment gauge — a very high PCR can indicate heavy put positioning (often read as bearish or, contrarily, oversold). It is descriptive context, not a signal to trade.