What is the legal test for "knowing possession" of information that is not disclosed to the public?

In addition, a "knowing possession" standard comports with the oft-quoted maxim that one with a fiduciary or similar duty to hold material nonpublic information in confidence must either "disclose or abstain" with regard to trading. See Chiarella v. United States, 445 U.S. 222, 227, 100 S.Ct. 1108, 1114, 63 L.Ed.2d 348 (1980). When the fiduciary is an insider who is not in a position to make a public announcement, the fiduciary must abstain. It would be consistent with the "disclose or abstain" rule that a tippee acquire the same duty as his fiduciary tipper.