Operational risk and equity prices

We use an empirical model to categorize firms into portfolios based on operational risk. Using these portfolios, we show that a strategy of buying firms in the highest decile of operational risk and shorting firms in the lowest decile of operational risk earned a positive but insignificant risk-adjusted average return of 0.72% per month from 1990 to 2000. However, from 2001 to 2010, the same strategy earned a significantly negative risk-adjusted average return of ?1.50% per month. This change occurred during a time characterized by an increasing number of high profile operational losses and regulatory changes surrounding operational risk.