In the current market environment, the value of your holdings may be fluctuating widely and it's natural to feel tentative about further investment. But regularly adding to an account that's designed for a long-term goal may cushion the emotional impact of market swings. If losses are offset even in part by new savings, the bottom-line number on your statement might not be quite so discouraging. And a basic principle of investing is that buying during a down market may help your portfolio grow when the market turns upward again.