There are countless reasons to feel disappointed when your 401(k) statement is showing how much money you’ve lost over the last 30 days. A typical portfolio that’s invested in a mix of stocks, bonds, real estate and cash is likely to be down 17% or more from last year right about now. When you see losses like that in black and white, it might seem insane not to contemplate taking at least some money out of the market. But hold on.