Option rho

Rho is one of the option Greeks, and it measures how much an option's price is expected to change for a one percentage point change in interest rates, holding everything else about the option constant. It captures the sensitivity of an option's premium to the broader interest rate environment, separate from movements in the underlying stock, time decay, or changes in volatility.

Call options generally have positive rho, meaning their value tends to rise as interest rates rise, while put options generally have negative rho, meaning their value tends to fall as interest rates rise. This happens because higher interest rates increase the cost of carrying a position in the underlying stock, which makes holding a call more attractive relative to owning the stock outright, and makes holding a put relatively less attractive. The effect comes directly out of the put-call parity relationship linking option prices to the risk free rate.

In practice, rho is the least influential of the main Greeks for most short-dated equity options, since interest rate changes over the life of a typical contract are usually small compared to how much the stock price itself, implied volatility, or time decay can move an option's value. Rho becomes more meaningful for options with a long time until expiration, such as LEAPS, where a sustained shift in interest rates has more time to affect the option's pricing, and for institutions managing large options books where even small sensitivities add up.