Options Theta
Calculates Theta, which measures the rate of time decay for an option.
Parameters
| Parameter | Type | Required | Description |
|---|---|---|---|
| CurrentStockPrice | number | Yes | Current underlying stock price |
| MarketOptionPrice | number | Yes | Current option market price |
| ExpiryDate | date | Yes | Option expiration date |
| OptionType | string | Yes | "Call" or "Put" |
| StrikePrice | number | Yes | Option strike price |
| RiskFreeRate | number | No | Risk-free rate (default 0.05) |
| ImpliedVolatility | number | No | IV as decimal |
Interpretation
- Theta is typically negative (options lose value over time)
- Higher for at-the-money options
- Accelerates as expiration approaches
Syntax
=mxls.opt_Theta(CurrentStockPrice, MarketOptionPrice, ExpiryDate, OptionType, StrikePrice, [RiskFreeRate], [ImpliedVolatility])Examples
When to Use
- Understanding time decay
- Options selling strategies
- Position decay analysis
- Income strategy planning
When NOT to Use
| Scenario | Use Instead |
|---|---|
| Price sensitivity | opt_Delta() |
| Delta sensitivity | opt_Gamma() |
| Volatility sensitivity | opt_Vega() |
| Rate sensitivity | opt_Rho() |
Common Issues & FAQ
Why is theta negative?
Options lose extrinsic value as time passes (time decay).
Excel Templates Using Options Theta
These ready-made MarketXLS templates call opt_Theta() in their worksheet formulas. Open one to see the function working inside a complete model.
Related Formulas
More MarketXLS Options formulas you can use in the same worksheet:
- Options Total Volume Historical
- Options Volume Leaders
- Put Interest (Specific Expiry)
- QM Get Option Chain Active Dynamic
- QM Get Option Chain At The Money Dynamic
- QM Get Option Chain Dynamic
- QM Get Option Chain In The Money Dynamic
- QM Get Option Chain Monthlies Dynamic
See opt_Theta used in a complete workbook: Live Option Chain Data in Google Sheets: What GOOGLEFINANCE Covers and Where MarketXLS Picks Up
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