Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
Using comprehensive time stamp data on earnings announcements collected from newswires, we show that earnings news announced within trading hours results in approximately 50% smaller immediate reaction compared to similar earnings announced outside trading hours. Negative news tends to be announced during trading hours, which, together with the reduced response, may allow for managerial opportunistic behavior. We also provide evidence that announcement timing is affected by internal corporate governance. Recent regulations that tightened firms’ governance are associated with a significant shift to announcing outside trading hours, especially for firms with better corporate governance. Our surveys of corporate managers corroborate these results.