Time decay
The steady loss of an option’s extrinsic value as expiration approaches, measured by theta. Decay accelerates in the final weeks for at-the-money options.
Decay is not a market opinion; it is arithmetic. An option is a wasting claim on future movement, and each passing day removes some of the movement it could have captured.
The practical asymmetry: buyers must be right about direction and timing, while sellers can be merely not-too-wrong. That convenience is paid for with tail risk, not received for free.
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