CallTheta Function: Returns the Black-Scholes value "Theta" for a Call option.

=CallTheta(UnadjustedPrice, StrikePrice, Years, Volatility, RiskfreeRate, DividendYield)

PutTheta Function: Returns the Black-Scholes value "Theta" for a Put option.

=PutTheta(UnadjustedPrice, StrikePrice, Years, Volatility, RiskfreeRate, DividendYield)

Description of parameters

For each Excel Function that calculates an Option Greek or other Options statistic, there are certain parameters required as shown in the formula(s) above. Not all functions use all parameters. Here is a
description of each parameter:

UnadjustedPrice: Current price of the underlying Stock.

Strike Price: Strike Price (aka Excercise Price).

Years: The time in years until the option's expiration.

Volatility: The annualized estimated volatility of the underlying security, expressed as a percentage greater than zero.

RiskFreeRate: Annualized risk-free rate of interest corresponding
a period roughly equal to the remaining life of the option, expressed in continuous compounding terms
(see ContCompRate function). Leave empty for 0.

DividendYield: The annualized dividend yield of the underlying
security, expressed in continuous compounding terms (see ContCompRate function). Leave empty for 0.