How to Track CreditDefault Swaps

You can track just by ticker what the credit default swap price is right now and what it expires because like insurance contracts, these have a term to them. Your money that you have in there right now is insured up to $250,000 should your broker fail. But not if you make a bad decision within your 401k, that's your problem. Is there a historical precedent set for a brokerage account, a brokerage going out of business and people losing money? Has that ever happened?