if you're a US Taxpayer, file a complaint with the SEC here: https://www.sec.gov/oiea/Complaint.html

It’s hard to do much. Senators can just tip off firms and friends.

The senators are probably thinking "What can you do?".

Hope the FBI does its job. That's on the President to prosecute and enforce corruption. One of the many duties of the President and the cabinet.

Write a letter