In the aftermath of the Covid-19 pandemic, the U.S. equity markets have witnessed a surge in the number of publicly listed companies. Using data for the three major U.S. stock exchanges (AMEX, NYSE, and NASDAQ), we find that the number of publicly traded companies went from 4,144 at the end of...

From 2010--2015, a group of traders illegally accessed earnings information hours before their public release by hacking several major newswire services. We use their informed trading as a natural experiment to investigate how efficiently markets incorporate private information in trades. 15\%...