"traditional" or "classical theory" of insider trading and "misappropriation theory"

The "traditional" or "classical theory" of insider trading liability, §10(b) and Rule 10b-5 are violated when a corporate insider trades in the securities of his corporation on the basis of material, nonpublic information. Trading on such information qualifies as a "deceptive device" under §10(b), we have affirmed, because "a relationship of trust and confidence [exists] between the shareholders of a corporation and those insiders who have obtained confidential information by reason of their position with that corporation."

The "misappropriation theory" holds that a person commits fraud "in connection with" a securities transaction, and thereby violates §10(b) and Rule 10b-5, when he misappropriates confidential information for securities trading purposes, in breach of a duty owed to the source of the information. Under this theory, a fiduciary's undisclosed, self serving use of a principal's information to purchase or sell securities, in breach of a duty of loyalty and confidentiality, defrauds the principal of the exclusive use of that information. In lieu of premising liability on a fiduciary relationship between company insider and purchaser or seller of the company's stock, the misappropriation theory premises liability on a fiduciary turned trader's deception of those who entrusted him with access to confidential information.

The two theories are complementary, each addressing efforts to capitalize on nonpublic information through the purchase or sale of securities. The classical theory targets a corporate insider's breach of duty to shareholders with whom the insider transacts; the misappropriation theory outlaws trading on the basis of nonpublic information by a corporate "outsider" in breach of a duty owed not to a trading party, but to the source of the information. The misappropriation theory is thus designed to "protec[t] the integrity of the securities markets against abuses by `outsiders' to a corporation who have access to confidential information that will affect th[e] corporation's security price when revealed, but who owe no fiduciary or other duty to that corporation's shareholders.

Read the classic case of "misappropriation theory" of insider trading : 

UNITED STATES, PETITIONER v. JAMES HERMAN O'HAGAN