Question about banks.

This is a decently serious question, banks cover up to $100,000 incase the bank closes down, but what do you do if you have $500,000,000? There wouldn't even be enough banks to spread it out in.

 

It is not possible To simply have 500 million dollars in a bank, you would need to have purchased stocks in the bank. And I believe that if you purchase stocks and they go down nobody owes you anything.