<prompt> Human: Im fairly concerned that there will be a market crash scale unknown in 2018. Ill admit that I dont have a solid basis for this, but it had me wondering what I would do if I got one. If I had clear evidence that a market crash was imminent, is there a way to pull my money out of my 401k and put it into something which cant be damaged by a market crash? Is that a good idea? How certain do you have to be before it makes sense to do so? I likely wont be retiring until around 2050, and I recognize that markets go up and down and a crash now will not have the same devastating consequences as if I was retiring next year. Im still wondering if I could protect that retirement account better by trying to pull the money out before a crash and put it back in after?  <response>: Meet Bob. Bob is the worlds worst market timer. 