Options Trading Glossary

Plain-English definitions of the terms you'll see across BlackOut and the Learn hub. Each links to a deeper guide where one exists.

0DTE (Zero Days to Expiration) — An option that expires the same trading day. Carries large, fast-decaying gamma, making intraday dealer positioning critical. See 0DTE SPX Options Strategy.

Call Wall — The strike above current price with the largest concentration of call gamma; often acts as resistance or a magnet. See Call Wall & Put Wall.

Dark Pool — A private trading venue where institutions buy and sell size away from the public exchange, with trades reported only after the fact. Roughly 40–50% of U.S. equity volume trades through dark pools. See What Is Dark Pool Trading?.

Dealer — A market maker who takes the other side of your options trades and hedges continuously to stay neutral. Their hedging is what moves markets intraday.

Dealer Gamma Exposure — A measure of how much dealers must buy or sell as price moves. The foundation of positioning analysis. See What Is Dealer Gamma Exposure?.

Delta — How much an option's price changes for a $1 move in the underlying. Also approximates the probability of finishing in-the-money. See Options Greeks Explained.

Delta Hedging — The continuous process by which market makers buy and sell the underlying to stay directionally neutral as delta shifts. The mechanical engine behind why positioning moves the market. See Delta Hedging Explained.

Gamma — The rate of change of an option's delta as the underlying moves. High gamma means hedging needs change quickly. See Options Greeks Explained.

Gamma Flip — The price where aggregate dealer gamma crosses from positive to negative — the line between a calm, pinning market and a fast, trending one. See Gamma Flip Explained.

Gamma Squeeze — A feedback loop where dealer hedging of short-gamma call positions forces them to chase price, amplifying a move. See Gamma Squeeze Explained.

GEX (Gamma Exposure) — Total dealer gamma aggregated across the options chain; positive stabilizes the market, negative amplifies it. See What Is GEX?.

Implied Volatility (IV) — The market's forecast of how much an underlying will move, priced into the option. Higher IV means richer premiums on both calls and puts. IV rank and IV percentile put current IV in the context of its own history. See Implied Volatility Explained.

Iron Condor — A four-leg options strategy that collects a credit by selling a call spread above price and a put spread below, profiting when the underlying stays within a range. See Iron Condor Strategy Guide.

Long Gamma — When dealers hedge against the move (sell rallies, buy dips), dampening volatility and pinning price.

Max Pain — The strike price at which the most options expire worthless and option sellers pay out the least. A secondary reference, not a primary signal — gamma walls tend to be more mechanically grounded. See Max Pain in Options.

Open Interest (OI) — The total number of outstanding option contracts at a given strike and expiration. Large OI concentrations drive the gamma walls and hedging flows that move the market. See Open Interest Explained.

Options Chain — The full table of every available option on an underlying, organized by strike, expiration, and type (call/put), showing bid/ask, volume, OI, IV, and the Greeks. See How to Read an Options Chain.

Options Flow — The stream of options trades hitting the tape. Useful only with context — opening vs. closing, bid vs. ask, hedged vs. directional. See How to Read Options Flow.

Put Wall — The strike below current price with the largest concentration of put gamma; often acts as support. See Call Wall & Put Wall.

Short Gamma — When dealers hedge with the move (buy strength, sell weakness), amplifying volatility. The regime behind fast selloffs and squeezes.

SPX — Options on the S&P 500 index, cash-settled and European-style — the primary market for dealer-gamma and 0DTE trading.

Theta — The amount of value an option loses per day from time decay alone. Accelerates as expiration approaches and is especially punishing on 0DTE contracts. See Options Greeks Explained and Theta Decay Explained.

Unusual Options Activity (UOA) — Volume in a specific contract that's meaningfully higher than its baseline. The real filter is whether volume exceeds open interest (new positions) and whether it's aggressive (sweeps at the ask). See Unusual Options Activity Guide.

Vega — How much an option's price changes for a 1-point move in implied volatility. Matters most on longer-dated options; nearly zero on 0DTE. See Options Greeks Explained.

Want the full picture? Start with the pillar guide: Dealer Gamma & Options Flow. Or see it all live →

BlackOut provides educational tools and market analysis only and does not provide investment advice. Options trading involves substantial risk and is not suitable for every investor.