It is ambiguous.
The only thing I can say with absolute certainty about insider trading is that anyone who can confidently say XYZ is or isn’t insider trading doesn’t know what they’re talking about.
I agree that the second one seems ambiguous and could certainly result in a lawsuit in the shareholders are unhappy.
I don't think the third one is insider trading, the banker had a duty to keep this information confidential, not you and you did not colluded. This looks a bit like the loan to Kodak that got leaked in the press because they had forgot to embargoed it. While it certainly not good looking for employees of the company to trade on this information, what could possibly reproached to outsiders once this news is all over the Internet? Even after the initial tweet had been removed, the news was out their.
Before someone is quick to say "how can you not know?!," there are some pretty ambiguous cases around trading on material, non-public information.
- Counting cars in parking lots as a proxy for sales.
- Your employer sees a drop in sales and is able to directly attribute it to a competitor. Can you buy shares in the competitor?
- You're at a bar in NYC and a drunk i-banker is trying to impress a girl and runs his mouth and talks about a pending acquisition.