The recent merger between US Airways and American Airlines was approved by federal and state antitrust authorities, after the merging parties agreed to divest slots and gates at certain “constrained” airports to low cost carriers. By analyzing the stock-market returns of rival airlines, we...

There is a growing concern that U.S. merger control may have been too lenient, but empirical evidence remains limited. Event studies have been used as one method to acquire empirical insights into the competitive effects of mergers. However, existing work suffers from strong identifying...