Has January 2016 been rough for stock market investors? Absolutely. One of the most important things to do, in my view, is to keep perspective and not make swift, emotional changes during times like these. With the help of the media, many investors see this kind of drop in such a short time (10% in a few weeks) and immediately think back to 2008. That financial crisis was the worst recession in 80 years. It is not a common occurrence. What is common are regular market corrections triggered by some macroeconomic event that are characterized by stock prices reacting far worse than underlying economic and corporate performance would indicate is rational. That is very likely what we are seeing right now. In fact, it might surprise people that we have actually witnessed many such events just since 2010.
For long-term investors (time horizon of 3-5 years or more), these are almost always opportunities to buy rather than sell.