[lmm]

Only if the analyst knows or should know that the employee is getting a "personal benefit" for sharing this information, or the analyst learns it in a context where they have a duty to keep it confidential. Handing an employee a sack of cash to tell you confidential information you then trade on? Illegal. Overhearing confidential information on the train and trading on that? Totally fine. Trading on confidential information from your brother-in-law? Illegal (family members are assumed to automatically meet the personal benefit test). Something you heard in a therapy session? Illegal (there's a duty of confidentiality).

Something your casual acquaintance tells you, with no close relationship and no obvious quid pro pro? That one's been litigated back and forth in recent years, with different cases coming out both ways (to the point that Matt Levine has a running joke about the sacred duty of golf-buddy confidentiality). You'd probably have to roll the dice in court.

[adament]

My understanding is that under current EU market abuse regulations trading on inside information* that you overheard on the train is still insider trading. Sharing inside information in a manner not required to fulfill your role (i.e. with an analyst if you are a regular employee, or with a specific analyst before the general analyst community if you are the management) is also a violation of MAR (dissemination) even if nobody trades on it. It is only if the information is public that you can trade on it (with an exemption for market makers).

* Under MAR confidential information is not necessarily inside information, as one of the prerequisites for the information to be inside information it must be likely that it has a significant effect on the price of a financial instrument if made public.