The goal of our analysis is to enhance the understanding of the value of antitrust regulatory activities, specifically the impact of investigations of anticompetitive behavior. The results suggest that prices significantly increased as soon as the targets of the investigation were made aware they were being investigated. Higher prices are suggestive of a more competitive market outcome, which in turn suggests that the benefits of an investigation begin accruing immediately upon awareness by the offending party. The higher prices remained as long as the investigation was open. After the investigation was closed, market prices systematically declined to the same low pre-knowledge state.