What is Rho? The Impact of Interest Rates on Option Value

Rho measures sensitivity to the risk-free interest rate. Learn why Rho is negligible for weeklies but vital for institutional long-term portfolios.

I analyzed the Fed's 2024 rate-cut cycle to determine when Rho ($\rho$) becomes a dominant factor in pricing. Rho measures the sensitivity of an option's price to changes in the risk-free interest rate $r$: $\rho = \frac{\partial V}{\partial r}$.

For standard equity options, Rho is often the least significant Greek. However, for LEAPS or high-notional institutional portfolios, it is critical. As interest rates rise, call options become more expensive (because the 'opportunity cost' of holding the stock is higher), and put options become cheaper.

Calculate the Rho of a 2-year call option and compare it to a 7-day call; you will see why the Fed's decisions only keep 'LEAP' traders awake at night.