Options Glossary

36 terms traders and their assistants ask about most, each with a plain-English definition, the conventional formula, and where the concept shows up as live data on ImpliedOptions.

Volatility

Implied Volatility (IV): Implied volatility is the market's forecast of how much an underlying will move, expressed as an annualized percentage and backed out of current option prices with a pricing model. Higher IV means options are priced for larger swings and cost more.
IV Rank: IV rank locates today's implied volatility inside its 52-week range on a 0–100 scale: 0 means IV is at its yearly low, 100 at its yearly high. It answers "is IV high for this ticker?" rather than "is IV high in absolute terms?"
IV Percentile: IV percentile is the percentage of trading days over a lookback window (usually one year) on which implied volatility closed below its current level. An IV percentile of 80 means IV has been lower than today 80% of the time.
Historical Volatility (HV): Historical volatility is the annualized standard deviation of an underlying's past returns over a set window, such as 20 or 30 trading days. It measures how much the price actually moved, in contrast to implied volatility, which measures how much option prices expect it to move.
Expected Move: The expected move is the range an underlying is priced to stay within by a given expiration, typically one standard deviation (about 68% probability), derived from implied volatility or from the price of the at-the-money straddle.
Volatility Skew: Volatility skew is the pattern of different implied volatilities across strikes for the same expiration. In equities, out-of-the-money puts usually carry higher IV than equivalent calls, reflecting demand for downside protection and the tendency of markets to fall faster than they rise.
Volatility Term Structure: Term structure is how implied volatility varies across expiration dates for the same underlying. Normally longer-dated options carry slightly higher IV (contango); before earnings or a known event the near-term expiration carries the highest IV, an inverted or "kinked" term structure.
VIX (CBOE Volatility Index): The VIX is the CBOE Volatility Index, a measure of the 30-day expected volatility of the S&P 500 derived from SPX option prices. It is quoted in annualized percentage points and is often called the market's fear gauge.

Greeks

Delta: Delta measures how much an option's price changes for a $1 move in the underlying. Calls have deltas from 0 to 1, puts from −1 to 0, and delta doubles as a rough estimate of the probability the option expires in the money.
Gamma: Gamma measures how fast delta changes for a $1 move in the underlying. It is highest for at-the-money options close to expiration; long options always have positive gamma and short options negative gamma.
Theta: Theta is the amount an option loses in value each day from the passage of time alone, with all other inputs held constant. Long options have negative theta; short options collect it.
Vega: Vega measures how much an option's price changes for a one-percentage-point change in implied volatility. Long options have positive vega and gain when IV rises; short options lose.
Rho: Rho measures the change in an option's price for a one-percentage-point change in the risk-free interest rate. Calls have positive rho and puts negative rho, and the effect is largest for long-dated options.

Positioning & Flow

Gamma Exposure (GEX): Gamma exposure aggregates the gamma of all open option contracts on an underlying, weighted by open interest, to estimate how much stock dealers must buy or sell to stay hedged as price moves. Positive GEX tends to dampen moves; negative GEX tends to amplify them.
Max Pain: Max pain is the strike at which the total dollar value of all expiring options is lowest, so option buyers collectively lose the most and option sellers keep the most premium. It is computed from open interest for a single expiration.
Open Interest (OI): Open interest is the number of option contracts for a given strike and expiration that are currently open: opened but not yet closed, exercised or expired. It is updated once per day after the close.
Options Volume: Options volume is the number of contracts traded in a session for a strike, an expiration, or an underlying as a whole. Each contract usually controls 100 shares, and volume resets to zero every trading day.
Put/Call Ratio: The put/call ratio divides put volume (or put open interest) by call volume (or call open interest). Readings above 1 indicate more put than call activity and are read as bearish or hedged positioning; readings well below 1 as bullish.
Options Flow: Options flow is the real-time stream of executed option trades, each tagged with size, premium, strike, expiration, execution price relative to the bid-ask spread, and inferred sentiment. Traders read it to see where large participants are positioning.
Sweep: A sweep is an option order split across several exchanges and filled at multiple prices to execute the whole size immediately, rather than resting on one exchange for a better price. Sweeps executed at the ask are read as urgent, high-conviction buying.
Block Trade: A block trade is a single large option transaction, typically thousands of contracts, executed on one exchange and often negotiated off the public order book before being printed. Blocks are usually institutional.
Unusual Options Activity (UOA): Unusual options activity is option volume or premium that is abnormal for the ticker: volume well above its average, volume exceeding open interest at a strike, or unusually large single trades. It flags where new, sizable positioning is happening.

Pricing & Mechanics

Black-Scholes Model: Black-Scholes is the foundational model for pricing European options from five inputs: underlying price, strike, time to expiration, risk-free rate and volatility (plus dividend yield in the Merton extension). Every Greek and every implied volatility is defined relative to it or its descendants.
Probability of Profit (POP): Probability of profit is the model-implied chance that an options position finishes with at least a $0.01 gain at expiration, based on current implied volatility and the position's break-even prices. It is not the probability of reaching maximum profit.
Moneyness (ITM, ATM, OTM): Moneyness describes where an option's strike sits relative to the underlying price. In-the-money (ITM) options have intrinsic value, at-the-money (ATM) strikes sit at the current price, and out-of-the-money (OTM) options have only extrinsic value.
Intrinsic and Extrinsic Value: An option's price splits into intrinsic value, the amount it is in the money right now, and extrinsic value, everything else: the premium paid for time and volatility. Out-of-the-money options are pure extrinsic value.
Break-Even Price: The break-even price is the underlying price at expiration where an options position neither makes nor loses money. For a long call it is the strike plus the premium paid; for a long put it is the strike minus the premium paid.
Assignment and Exercise: Exercise is the option holder's right to buy (call) or sell (put) the underlying at the strike; assignment is the seller's matching obligation. US equity options are American style and can be exercised any time before expiration; options in the money by $0.01 or more are exercised automatically at expiration.
Bid-Ask Spread: The bid-ask spread is the difference between the highest price buyers will pay (bid) and the lowest price sellers will accept (ask) for an option. It is the immediate cost of trading and a direct measure of liquidity.
0DTE Options: 0DTE options are contracts expiring on the current trading day. They carry extreme gamma and theta: small moves in the underlying swing their value violently, and their remaining extrinsic value goes to zero by the close.

Strategies

Vertical Spread: A vertical spread buys one option and sells another of the same type and expiration at a different strike. It caps both maximum gain and maximum loss at the difference between strikes, and it can be built for a debit (directional) or a credit (income).
Straddle: A straddle buys (or sells) a call and a put at the same strike and expiration, usually at the money. A long straddle profits from a large move in either direction; a short straddle profits if the underlying stays near the strike.
Strangle: A strangle buys (or sells) an out-of-the-money call and an out-of-the-money put with the same expiration. It costs less than a straddle but needs a larger move to profit, and the short version collects less premium in exchange for a wider profit zone.
Iron Condor: An iron condor sells an out-of-the-money put spread and an out-of-the-money call spread on the same expiration for a net credit. Maximum profit is the credit if the underlying expires between the short strikes; maximum loss is the wider spread width minus the credit.
Covered Call: A covered call pairs 100 long shares with one short call against them. The premium received lowers the cost basis and provides income; in exchange, upside above the strike is capped and the shares may be called away at expiration.
Cash-Secured Put: A cash-secured put sells a put while holding enough cash to buy 100 shares at the strike if assigned. It earns premium for the obligation to buy the stock at a lower price and is used to acquire shares at a discount or as an income strategy.