While the S&P 500 was down 3.6 percent in January 2014, it was up 11.4 percent for the year. The first five-day rule did not work either for stocks, since the S&P was off 0.6 percent in that period last year.
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A CNBC survey of Wall Street strategists shows they expect a 7.8 percent gain for the S&P in 2015 from 2014 levels.
"Obviously people watch it. But would I make an investing decision for the next 245 trading days based on it? No," said Michael O'Rourke, chief market strategist with JonesTrading. "Most of the time we're up (in the first five days), and most of the time the market is up. The rally for the past two days was silly. That's the best way to describe it."
But Jeffrey Hirsch, editor-in-chief of the Stock Trader's Almanac, said it's an encouraging sign, and like the Wall Street strategists, he sees a gain for the year.
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He said there's only been three instances where the Santa rally did not work out where the first five days were positive. In two of those years, 1971 and 1968, the market was higher for the year. In 1994, it was slightly negative, down 1.5 percent.
But he said he won't judge it until he sees what the January barometer shows at the end of the month.