Options Trading Glossary

Core terms used in Indian options trading. Each definition links to the StockMojo tool that visualizes the concept.

• Max Pain

  Max pain is the strike price at which the maximum number of options (calls + puts combined) would expire worthless, causing the greatest aggregate loss to option buyers. It's calculated by summing the rupee value of all in-the-money options at every strike for the upcoming expiry, then identifying the strike with the smallest total. Traders watch max pain because the underlying often gravitates toward this level in the final session before expiry.

  See it in action: Max Pain Calculator

• Open Interest

  Open interest (OI) measures the total number of outstanding option contracts at a given strike and expiry. Unlike volume, which counts every trade, OI only counts new positions opened or existing ones closed. Rising OI alongside rising price signals fresh long positions; rising OI with falling price signals fresh short positions. OI resets at every contract expiry.

  See it in action: Open Interest Tool

• Put Call Ratio (PCR)

  PCR divides total put OI (or volume) by total call OI (or volume). A PCR above 1 means more puts are open than calls — often interpreted as bearish sentiment, but used by experienced traders as a contrarian bullish signal at extremes. PCR below 0.7 is typically considered bullish; above 1.3, bearish (or contrarian-bullish).

  See it in action: Put Call Ratio

• Implied Volatility (IV)

  Implied volatility is the volatility figure that, when plugged into an option pricing model (Black-Scholes), produces the option's current market price. It represents the market's forward-looking expectation of price movement. High IV means expensive options; low IV means cheap options. IV typically rises before earnings or major events and crashes ("IV crush") after.

  See it in action: IV Chart

• IV Rank

  IV Rank scales current IV between its 52-week low (0%) and high (100%). A rank of 80% means current IV is higher than 80% of the past year's range — typically a signal to favor selling premium. IV Rank is preferred over raw IV because it normalizes across different underlyings.

  See it in action: IV Chart

• IV Percentile

  IV Percentile counts how many days over the past year had IV lower than today's reading. A percentile of 90% means IV has been lower than today on 90% of past trading days. Unlike IV Rank, IV Percentile is not skewed by single extreme spikes — it's a more stable measure of where IV currently sits in its historical distribution.

  See it in action: IV Chart

• Historical Volatility (HV)

  Historical volatility measures the standard deviation of an underlying's returns over a past period (commonly 20 or 30 days), annualized. Comparing IV to HV reveals whether options are pricing in more or less movement than recently realized — a fundamental input for premium-selling strategies.

  See it in action: IV vs HV

• Theta

  Theta is one of the option Greeks. It quantifies how much premium an option loses each day if everything else (price, IV) stays constant. Theta is non-linear: it accelerates dramatically in the final two weeks of an option's life and is highest at the money. Premium sellers profit from theta; premium buyers fight it.

  See it in action: Premium Decay

• Gamma

  Gamma measures how fast delta changes when the underlying moves by one rupee. ATM options have the highest gamma; deep ITM and OTM options have low gamma. High gamma means high sensitivity to price movement, which is why expiry-day ATM options can swing wildly.

  See it in action: Gamma Exposure

• Smart Money / Smart OI

  Smart money in the F&O context refers to large institutional traders whose orders move significant volume and OI. Smart OI tools attempt to surface this activity by tracking net OI changes (puts vs calls, ITM vs OTM) in real time and inferring whether institutions are net long, net short, or hedging.

  See it in action: Smart OI

• OI Buildup

  OI buildup categorizes the relationship between OI change and price change in a single bar: long buildup (price up, OI up), short buildup (price down, OI up), long unwinding (price down, OI down), short covering (price up, OI down). It's the simplest way to read aggregate trader positioning intraday.

  See it in action: Open Interest

• Straddle

  A straddle is an options strategy of buying (long straddle) or selling (short straddle) both a call and a put at the same strike, usually ATM. Long straddles profit from large moves in either direction; short straddles profit from time decay if the underlying stays range-bound. The combined premium represents the market's expected move.

  See it in action: Straddle Chart

• Premium Decay

  Premium decay describes how an option's extrinsic value erodes over time. The decay is slow at first, accelerates in the last two weeks, and becomes extreme on expiry day itself, where ATM options can lose most of their value within a single session. Visualizing this decay helps option sellers time entries and exits.

  See it in action: Premium Decay

• Strike Price

  The strike price is the price at which the holder of an option has the right to buy (call) or sell (put) the underlying. Strikes are listed at fixed intervals — for Nifty, every 50 points; for BankNifty, every 100. The relationship between strike and underlying price determines whether an option is in-the-money, at-the-money, or out-of-the-money.

  See it in action: Option Chain

• Expiry

  Expiry is the date on which an option contract terminates. Indian index options have weekly and monthly expiries (Nifty on Thursdays, BankNifty monthly on the last Wednesday), while stock options expire on the last Thursday of the month. On expiry day, options are settled to their intrinsic value — out-of-the-money options expire worthless.

  See it in action: Option Chain