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Why would they dig deep?Whenever an outsized high-risk position pays off, multiple regulators--at the SRO, state and federal levels--investigate. Mostly for insider trading. Sometimes in response to investor complaints or broker arbitration proceedings.
These are well-paid professionals at the SEC, CFTC, FINRA, state financial services regulators, Federal Reserve, OCC, Treasury, and a bajillion other acronym agencies. Some of them are there while they wait for something better in industry. Many eye an administration appointment or political office. These are motivated people with comprehensive data across multiple markets, all tied to the natural persons behind accounts.
Corollary: One will notice that most insider trading busts happen to mid-level employees at publicly-traded companies. Not traders or hedge fund managers. A large part of this comes down to the general public having no idea how competent securities regulators are. So while someone in the industry would never e.g. text about insider trading before buying out of the money options in a relative's name, Midwestern CFO's daughter sees nothing risky about that.