A "401(k)" is not a monolithic entity. In practice, most employers offer a choice of funds, with the most popular being a year-targeted fund that rebalances between equities and bonds as you get closer to retirement. Having said that, you can probably dump your entire portfolio into government bonds, small cap stocks, or euro futures.
I have had jobs with good 401ks and terrible ones. The terrible ones usually have some bond/ saving option. When you leave the job you stick the money in a full service brokerage IRA. The problem is when you are at the same job for too long.