17 C.F.R. § 240.10b-5
It shall be unlawful for any person, directly or indirectly, by the use of any means or instrumentality of interstate commerce, or of the mails or of any facility of any national securities exchange,
(c) To engage in any act, practice, or course of business which operates or would operate as a fraud or deceit upon any person,
in connection with the purchase or sale of any security.
(Sec. 10; 48 Stat. 891; 15 U.S.C. 78j)
[13 FR 8183, Dec. 22, 1948, as amended at 16 FR 7928, Aug. 11, 1951]