The Markets (as of market close August 31, 2015) Despite favorable economic news later in the month, the U.S. stock market was unable to recover all of its losses and closed in negative territory compared to July. Key factors in the downturn include fear that China's economy is weakening, the steep drop in the price of oil, lackluster corporate earnings reports, and the potential for an imminent interest rate hike. Each of the major market indexes listed here dropped between 6% and 7.50% for the month.

"Sell in May, go away" wasn't a winning strategy last month. Investors regained interest in Nasdaq stocks, giving the index its strongest gains since February. The Russell 2000, which along with the Nasdaq had been pummeled in April, also managed to eke out a positive performance in May. Meanwhile, by the end of the month, both the S&P 500 and the Dow had set new record closing highs, even shrugging off a disappointing Q1 GDP report. And renewed confidence in emerging markets helped power gains in the Global Dow; for the second straight month, it had the second-best year-to-date performance of the five indices in the table below.

The rotation out of momentum stocks that began in early March continued in April, hitting many of the tech and biotech high-fliers that had soared earlier in the year. That cost the Nasdaq and Russell 2000 dearly, leaving both with negative year-to-date returns. 

Equities recovered from January's losses in fine style. The Nasdaq continued to lead the pack year-to-date, but by the end of the month the S&P 500...