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Theta: Definition

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Simple Definition

How much value an option loses each day due to time passing.

Why It Matters

Theta is the daily cost of holding options. A theta of -0.05 means your option loses $5 per day (per contract) even if the stock doesn't move. This is why option buyers race against time while sellers collect theta as income - it's the foundation of strategies like covered calls.

Key Points

  • Theta accelerates as expiration nears - options lose value fastest in the final weeks
  • ATM options have the highest theta; deep ITM and OTM options decay slower
  • Option sellers ('theta gang') profit from time decay working in their favor

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Common Questions

How much value an option loses each day due to time passing. Theta is the daily cost of holding options. A theta of -0.

Theta is the daily cost of holding options. A theta of -0.05 means your option loses $5 per day (per contract) even if the stock doesn't move. This is why option buyers race against time while sellers collect theta as income - it's the foundation of strategies like covered calls.

Theta accelerates as expiration nears - options lose value fastest in the final weeks

ATM options have the highest theta; deep ITM and OTM options decay slower

Option sellers ('theta gang') profit from time decay working in their favor