Theta is the Greek letter representing time decay. Every day that passes, an option loses a portion of its extrinsic value. For option buyers, Theta is the enemy. For option wheel traders (sellers), Theta is the strongest ally.
You want the options you sell to decay in value so that you can buy them back cheaper or let them expire worthless. Theta decay accelerates as the option approaches expiration, especially in the last 30 to 14 days, which is why many wheel traders prefer 30-45 day or weekly expirations.
The Theta Curve: Theta is not linear. An option with 60 DTE decays slowly. An option with 7 DTE decays rapidly. This non-linear acceleration is why selling options in the 30-45 DTE range is considered the "sweet spot" by many professional options sellers.
Theta vs. Gamma: As expiration approaches, Gamma (the rate of change of Delta) increases sharply. High Gamma means the option's price can move violently on small stock moves. This is why some traders close or roll positions before the last week of expiration, even if Theta is at its highest.
Examples of Theta Decay in Action
- 1An option with a Theta of -0.05 will lose $5 of value per contract every single day, assuming the stock price and volatility do not change.
- 2A 45 DTE option with $3.00 of extrinsic value loses roughly $0.067 per day at a uniform rate (illustrative — actual decay is non-linear).
- 3A weekly option expiring Friday with $0.50 of value on Monday may be nearly worthless by Thursday afternoon.