If you're 20 years from needing it you don't need to worry about protecting it from a crash since you have time to wait for the market to recover. If you could

If you're 20 years from needing it you don't need to worry about protecting it from a crash since you have time to wait for the market to recover. If you could perfectly predict the seemingly-imminent crash then you'd be better off selling all your shares just before and buying government bonds instead, then reversing that when the stock market hits the bottom. But since you can't predict it, there's not much point doing anything (you can rebalance a bit from stocks to bonds if it makes you feel better but the impact will be minimal). The growth you'll miss out on from selling too early and buying too late will almost certainly outweigh the benefit.