
Re: "dumb question": Where are invested $$ held?
I'm not an expert on this topic but I would suggest doing a little research into which bank is the most financially secure. The results from the federal government's "stress test" on banks may be a good tool.
If we have another panic as we had in September of 08' you could always diversify your funds at that time. Also, keep in mind that if a major bank is about to default, the federal government is likely to step in as it did in 08' with Citigroup, Bank of America, AIG, etc.