You are riding the subway in NY when you overhear 2 people you don't know talking about an upcoming merger news not yet public. They seem to know their stuff. If you buy stock based on this information and profit when the information turns out true you have:

a) certainly benefitted but are an outsider and so your actions are probably not illegal

b) engaged in insider trading that is probably illegal

c) not engaged in insider trading because you are not an insider

d) not engaged in insider trading because once you overheard the information is public

e) violated the Insider Trading Sanctions Acts and you could face criminal charges