Mikestrek is right to a point. Unless you need to cash out a long-term investment vehicle like the 401K, just sit tight, accept the fact that your investment may be worth 10% less (or more) than it was at the beginning of the year, and wait for things to improve. If you're depositing money in each month, think of how many MORE shares that you're getting with your same percentage contribution.
You should also make sure that you set your automatic rebalancing tool in the 401K to rebalance your funds at least every 6 months. This way, your funds "reset" themselves to your chosen mix. So, if you're international stock is up 4% and your domestic small-cap stock is down 10%, your automatic rebalancing act will lock in the 4% gains and purchase more of the stock that's "on-sale" which is down 10%. Then, you have that many more shares in your account when the small-cap starts to rise.
Good luck.