On June 25 1997, the US Supreme Court held in United States v O'Hagan, 117 S Ct 2199 (1997), that it is a violation of the US securities laws for corporate outsiders to trade in securities for personal profit using material, non-public information in breach of a fiduciary duty owed to the source of the information. The Court thus ratified the misappropriation theory of liability, which has been used in nearly half the insider trading cases brought by the Securities and Exchange Commission (SEC) in recent years.
September 30 1997