Glossary / Instruments
Theta decay
Definition
The loss of option value as expiry approaches.
Why it matters
Theta accelerates in the final weeks, which is why holding long options through quiet sessions is expensive.
Example
A $2.00 option 30 days out with -0.04 theta loses about $4 a day per contract, and that decay accelerates in the final two weeks.
How to track it in a journal
TradeStack calculates the core performance numbers — win rate, average win and loss, profit factor, expectancy, drawdown and consistency — automatically from imported trades, so theta decay stops being something you estimate and becomes something you read.
Related terms
Tick value
The dollar value of the smallest price increment of a contract.
Pip
The standard smallest price move in a currency pair, usually 0.0001.
Lot size
The trade unit in forex: 100,000 units for a standard lot.
Contract specifications
The exchange definition of a futures contract: size, tick, hours and expiry.
Keep reading
Trading journal guides
Expectancy, profit factor, drawdown, backtesting and the PDT rule.
Free trading calculators
Position size, risk-reward, expectancy and options profit.
Expectancy calculator
Expected profit per trade from your own numbers.
Broker CSV export guides
Step-by-step exports for Tradovate, NinjaTrader, IBKR and more.
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