Proving that someone has been responsible for a trade can be difficult because traders may try to hide behind nominees, offshore companies, and other proxies. The Securities and Exchange Commission prosecutes over 50 cases each year, with many being settled administratively out of court. The SEC and several stock exchanges actively monitor trading, looking for suspicious activity.[8][9][10] The SEC does not have criminal enforcement authority, but can refer serious matters to the U.S. Attorney's Office for further investigation and prosecution.