You're wrong. Bernie Madoff's campaign did not have any shares and therefore they were not listed on the stock market. It was a common ponzi scheme, when clients gave their money to a fraudster at a high percentage, and due to which the first "investors" received a good profit.
If we take the stock market as a whole, then I would not consider investing in companies that are not American, since the legislation of not all countries provides for insurance if the shares were purchased through a broker.
Thanks for the pointing out, I thought that was also sold their share publicly.
Anyway, definitely it would be better decision to focus on the American companies for buying the shares. But still we should be care about choosing the company just because an American company it doesn't guarantee 100% that there is no possibility of fraud.
There can be example these companies like- WorldCom, Enron etc