The Supreme Court of the United States has held that a cause of action under rule 10b-5 must be based on conduct that could be considered manipulative or deceptive; breach of fiduciary duty without deceit is not fraud under the rule.
Santa Fe Industries, Inc. v. Green, 430 U.S. 462 (1977).
Robert G. Devlin,
Corporations - Securities Exchange Act of 1934 - Rule 10b-5 - Fraud,
Duq. L. Rev.
Available at: https://dsc.duq.edu/dlr/vol16/iss1/11