<prompt> Human: What happens to a 401k type account when you retire? Is it turned into an annuity based upon the amount? Does it collect interest of any kind? Can market fluctuations affect it...like the 07 meltdown?  <response>: 401k is just an account. Nothing happens unless you or the provider does something. The assets in the account just keep on doing what they do -- grow, get dividends, crash, etc.You can keep it as is if you already invest in a target date fund, set up periodic withdrawal, roll over to IRA, etc. 