The Wall Street Journal's coverage of financial markets in 2012 performed a rare and extraordinary service: It exposed evidence of hidden manipulation by corporate executives and professional traders that the markets' official government watchdogs were utterly unaware of. Reflecting potential widespread harm to millions of ordinary investors, federal prosecutors and securities regulators raced to follow the Journal stories with major investigations. A team of reporters spent six months creating a database examining how more than 20,000 corporate executives traded their own companies' stocks over the course of eight years. What the team found was disturbing: More than 1,000 executives had generated big profits, or avoided big losses, by trading their company stock in the days ahead of corporate news announcements that led to big moves in the shares. The Journal also exposed a regulatory loophole that had helped the executives take advantage of inside knowledge ahead of other investors. The Federal Bureau of Investigation, the Manhattan U.S. Attorney's office and the Securities and Exchange Commission all launched investigations the day the Journal article appeared.