Financial disclosure records show Indiana Democrat Evan Bayh earned nearly $6.3 million since the beginning of 2015.
Most of that total came from a private equity fund and a law firm.
The personal financial disclosure report filed late Sunday also shows Bayh and his wife have assets roughly worth between $14 million and $48 million.
Bayh served in the Senate from 1999 to 2011. He is now running to get his seat back and help the Democrats wrest control of the chamber.
The Associated Press reported Saturday that Bayh spent substantial time during his final year as a senator searching for a private sector job.
Bayh reported income of just over $2 million from Apollo Global Management and $1.9 million from the law firm McGuire Woods.
