After what could be described as a steady "melt-up" for the stock market in 2017, volatility has reared its head in the early going of 2018. For the first time in history last month, the nearly 122-year-old Dow Jones Industrial Average (DJINDICES: ^DJI) ended lower by more than 1,000 points during a single trading session not once, but twice -- minus 1,175 points on Feb.