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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.
Quick answer
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.
Theta measures daily time-value decay and it accelerates as expiration nears — an at-the-money option loses time value fastest in its final weeks.
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.
ApexVol Terminal
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Chains, IV rank, expected move and dealer positioning for 5,500+ US stocks and ETFs.
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- IV rank and percentile
- Expected move and GEX
- Screener and strategy P&L
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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
Theta is the core trade-off between expiration cycles. Weeklies concentrate decay (and risk) into days; monthlies spread it out. Compare the two side by side: weekly vs monthly options.
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Greeks Calculator- Written by
- ApexVol Research Team
Quantitative options research. All calculations use live institutional-grade data — the same source professional volatility desks use. - Reviewed by
- Ryan Silk, ApexVol Founder
Reviewed for technical accuracy. 10+ years trading options; built ApexVol's pricing engine, Greeks model and IV-rank methodology.
Revised as market conditions and institutional data change. Last revised 2025-01-21. How we research →
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