Don't Be Afraid of the Dark

Don't Be Afraid of the Dark

A while back, a study found that the stock market tended to have rough days on those Mondays in the autumn just after we switched off of daylight savings time, and suggested that the loss of those daylight hours (or a lack of sleep) might be depressing stock traders, and causing those gains. In fact, the worst Mondays of the year tend to come in the fall, when the S&P 500 has suffered average losses of as much as 8 percent.

But if you're thinking of making some trades to take advantage of this year's switch back to standard time - which is coming up on November 6 - that might not be a wise idea. Another researcher has gone back to the original study, and found that the real explanation for the market woes was not a lack of afternoon sunshine but dim economic news.

The second researcher, Jeffrey Gerlach, did find those drops on autumn Mondays, but determined that they were the result of "seasonal patterns in market-related information." In other words, it's the result of the same old things that always drive the markets.