The gaming industry has decided to self-regulate the sale of loot boxes by sharing the odds of receiving rare items in advance.
In June, it had been reported that the FTC was preparing a potential probe, but the earnings report confirms that the investigation is under way.
The internal emails appear to show that the boss knew some of its practices were questionable, and it comes as Facebook faces regulatory scrutiny.
There's legal precedent for the Federal Trade Commission to look into past mergers, but insiders are skeptical that it will touch any of the big tech companies.
The Federal Trade Commission has been investigating whether the leak of Facebook data to Cambridge Analytica violated an earlier settlement.