Investors were cheerfully dancing last month after the stock market posted its best January in 30 years and the best monthly performance since October 2015 (see chart below). More specifically, the S&P 500 index started the year by catapulting +7.9% higher (the best January since 1987), and the Dow Jones Industrial Average climbed 1,672 points to 25,000, or +7.2%. But over the last few months there has been plenty of heartburn and volatility. The December so-called Santa Claus rally did not occur until a large pre-Christmas pullback. From the September record high, stocks temporarily fell