Stocks fell in January for just the 8th time since 1929. The last seven times that happened, the rest of the year sucked.

The S&P 500 has had a rough start for 2015.

The index fell by 3.1% in January.

A weak January is not just unusual: It's historically an ugly signal, according to the New York Stock Exchange's Rich Barry.

"This year is only the 8th since 1929 to post a January loss after 3 or more consecutive up years," Barry said. "All prior 7 closed down for the year, (avg -14.8%), and all 7 were followed by a recession (according to the National Bureau of Economic Research) on average 7 months later. The prior years: 1953, 1957, 1973, 1981, 1990, 2000, 2008."

But that's just history. And we're talking about just one month.

The S&P 500 was down 1.3% on Friday. Data showed that US GDP missed estimates and slowed to 2.6% in Q4 from 4.0% in the previous quarter, even as personal consumption jumped 4.3% in the fourth quarter.

Here's a chart of the wild ride the S&P 500 had in the past month.