The traders' rule and long‐term options

Studies show that option traders prefer using the traders' rule to price short‐term options over more mathematically sophisticated models. This study uses Standard & Poor's 500 index option data to determine whether the traders' rule also outperforms mathematically more sophisticated models in pricing long‐term options. The results show that, while the traders' rule still enjoys smaller pricing errors for short‐term options, more mathematically sophisticated models perform better for long‐term options. This result may reflect the greater liquidity of short‐term options, which are far more actively traded than longer‐term options.