So many errors in your post. D & O insurance policies expressly do not cover fraud. This is spelled out in all policies. If not, no insurance firm would issue such insurance knowing the insured would effectively be given carte blanche for malfeasance.
Then you say the SEC doesn't prosecute, the FBI does. The first part is correct. The SEC is limited to civil actions, not criminal. However, it is the Department of Justice (DOJ), not the FBI, who can criminally prosecute. The FBI is only an investigative agency not a prosecutorial agency.