The first scam I was involved in was GM in 1990. Our firm was the managing underwriter for GM's secondary. I finally knew the system was rigged. I knew our trading department was shorting the stock leading right into the secondary pricing. Guess where the stock landed a week later.
It is what is, we are not big enough to break the system. That is why I left and went into the trading department.
I don't know for a fact, but I think General Motors Board and legal were involved too.