Rule 10b-5 is a regulation created under the Securities Exchange Act of 1934 that targets securities fraud. This rule makes it illegal for anybody to directly or indirectly use any measure to defraud, make false statements, omit relevant information, or otherwise conduct business operations that would deceive another person in the process of conducting transactions involving stock and other securities.

Rule 10b-5 is formally known as the Employment of Manipulative and Deceptive Devices.