If you are young and have started a retirement account of some sort. Or, if you are thinking about starting a retirement account, don't attempt to react to market fluctuations. Since the first of the year, the market has been tanking, literally. It's important to think long term here. You are periodically (throughout ups and downs) investing in the market. Some months (or weeks), you'll buy high and others you'll buy low. See my previous post on this, here. But overall you'll be saving for your retirement and watching it generally increase over the years. As with anything involving risk, it can't always go up, but overtime the trend should point upwards.

So what if the market is tanking and you're planning on retiring in 30 - 40 years. Keep periodically contributing all the way down and when the market recovers, you'll be making money all the way back up. As you get closer to retirement, then you want to start thinking about investing more conservatively and moving investments around accordingly.

Stick to quality funds and keep contributing at least every month. Times will be good and times will be bad, but overall, if you keep investing your retirement will be great!