Should 401(k) investors fear September?

The turning of the calendar to September might do what fears of a trade war and talk about the impeachment of President Donald Trump could not: cause stock prices to fall.

September, the worst-performing month for the Dow Jones industrial average in the past 50 years, has been an even spookier month for investors than October, a month best known for stock market crashes in 1929 and 1987. The Dow has dipped 0.87 percent, on average, in September and finished higher only about one-third of the time (36 percent), according to data going back 50 years from Bespoke Investment Group. Tuesday, the Dow dipped 0.1 percent. “September is the banana peel month, as some of the largest slips tend to take place during this month,” Ryan Detrick, senior market strategist at LPL Financial, noted in a report. A good example is September 2008, when the Dow, spooked by the bankruptcy of Lehman Brothers, plunged 6%.

The stock market has a lot of things working in its favor. Corporate profits are growing at the best pace since 2010, and the economy last quarter posted its best growth rate in four years.

With stocks trading near record highs, and uncertainty related to trade and the outcome of the mid-term U.S. election hanging over markets, LPL’s Detrick said he would be “surprised if volatility didn’t pick up.”

Still, Bespoke data show that in years when the Standard & Poor’s 500 has been up more than 5 percent for the year heading into September, the broad market gauge rose 0.36 percent in September and 4.51 percent the rest of the year.