Share your insights or perspective on the financial matter presented in the input.

Is there any drawback in putting all my 401K into a money market fund?
What you're describing is called timing the market.  That is, if you correctly predict when the market will drop, you can sell before the drop, wait for the drop, then buy after the drop has occurred.  Sell high, buy low. The fundamental problem with that, though, is: What ends up happening, on average, is you end up slightly behind.  There's quite a lot of literature on this; see Betterment's explanation for example.  Forbes (click through ad first) also has a detailed piece on the matter. Now, we're not really talking HFT issues here; and there are some structural things that some argue you can take advantage of (restrictions on some organizational investors, for example, similar to a blackjack dealer who has to hit on 16).  However, everyone else knows about these too - so it's hard to gain much of an edge. Plenty of people say they can time the market right, and even yourself perhaps you timed a particular drop accurately.  This tends to lead to false confidence though; how many drops that you timed badly do you remember? Ultimately, most investors end up slightly down when they attempt to time the market, because of the transaction costs (if you guess two drops, one 'right' and one 'wrong', and they have exactly opposite gains/losses before commissions, you will lose a bit on each due to commission), and because of the overall upward trend in the market (ie, if you picked at random one month a year to be out of the market, you'd lose around 10% annualized gains from doing that; same applies here). All of that aside, there is one major caveat: risk tolerance.  If you are highly risk tolerant, say a 30 year old investing your 401(k), then you should stay in no matter what.  If you're not - say you're 58 and retiring in a few years - then knowledge that there's a higher risk time period coming up might suggest moving to a less risky portfolio, even at the known cost of some gains.