China-based hackers rifled the computers of DuPont at least twice in 2009 and 2010, hunting the technological secrets that made the company one of the world's most successful chemical makers. It's not something investors would have learned from DuPont's regulatory filings, or from those of other companies victimized by hackers. The 10-K's DuPont submitted to the U.S. Securities and Exchange Commission over the period don't identify hacking as even a significant risk, much less reveal what two U.S. intelligence officials later said was a successful case of industrial espionage. Over the next three months, as publicly traded companies file 10-K's, investors may ...