Matt Levine—a columnist at Bloomberg who is both smart and hilarious; his Money Stuff newsletter is excellent—has a recurring theme of “everything is securities fraud.”
The theory: anything that effects the stock price of the company and isn’t disclosed as soon as possible is securities fraud.
Company doesn’t disclose a security breach? Securities fraud. Board buries a sexual harassment settlement with the CEO? Securities fraud.
If you buy stock after the event but before the event is disclosed, you were trading when the company had material information that could effect the stock price. That’s securities fraud.
Levine is both joking and not that really _anything_ could be prosecuted under this, and the SEC has seemed to make some prosecutions under this theory that feel more like, “what you did was shitty and maybe not exactly illegal or we don’t have exact evidence so we’ll prosecute you under this super broad statute.” Wire fraud seems to be applied in a similar manner.
(I’m not a lawyer and this is not legal advice, just some things I’ve read and now you’re reading on the internet from a random commentor. The above is how I understand it.)