Theta Decay: How Time Erodes Option Value
Master theta decay—the relentless force that erodes option value every day and how to make it work for or against you.
Theta Decay
is the rate at which an option loses value due to time passing. As expiration approaches, extrinsic value shrinks—this is theta decay.
Theta is always negative for long options (you lose value daily). Sellers collect this decay as profit. Decay accelerates in the final weeks before expiration.
Options lose value every day from time decay. Theta tells you how much (per day). Decay accelerates near expiration. Buyers fight theta. Sellers collect theta. ATM options have highest theta.
What Is Theta Decay?
Every day that passes, options lose some extrinsic (time) value. This erosion is theta decay.
Theta is expressed as dollars per day. A theta of -0.05 means the option loses $5 per day per contract.
At expiration, all extrinsic value is gone—only intrinsic value remains.
How Decay Accelerates
Theta decay isn't linear—it accelerates near expiration. Most decay happens in the final 30 days.
- 60+ DTE: Slow decay
- 30-60 DTE: Moderate decay
- 14-30 DTE: Accelerating decay
- 0-14 DTE: Rapid decay
Theta by Strike
ATM options: Highest theta (most extrinsic value to lose)
OTM options: Moderate theta
Deep ITM options: Lowest theta (mostly intrinsic value)
Using Theta
For Buyers
Theta works against you. Buy options with enough time for your thesis to play out. Avoid short-dated options unless you expect immediate moves.
For Sellers
Theta works for you. Sell options 30-45 DTE to capture accelerating decay. Profit if stock stays still.
Key Takeaways
- Time decay erodes option value daily
- Decay accelerates near expiration
- ATM options have highest theta
- Buyers fight theta, sellers collect it
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