It also looked into what it deemed inappropriate behaviour, including touching staff, taking unaccompanied female members of staff to lunch or on shopping trips, and messaging them outside of work.
But Mr Odey used his position as the majority shareholder of OAM to remove members of its executive committee and appoint himself as its sole member, meaning he could decide a disciplinary hearing into his conduct could be "indefinitely postponed", the FCA found.
This happened on two occasions, meaning the hearing was not held until a year after it had been originally scheduled.
The regulator said Mr Odey showed a "reckless disregard" for OAM's governance and caused the company to breach rules in order to protect his own interests.
In March 2022, when Mr Odey appointed himself as the sole committee member for the second time, OAM managed around £2.8 billion worth of funds.
OAM is in the process of being wound down and is no longer authorised by the FCA, having filed for liquidation last year.
The investment management and advisory firm founded by Mr Odey in 1991 made headlines for its large bets on the British economy, making hundreds and millions of pounds from the Brexit vote in 2016.
Mr Odey has referred the FCA's decision to the Upper Tribunal which could decide to uphold or overrule the fine and City ban.