A chart of the Dow Jones Industrial Average's performance during the past 18 months looks similar to the Dow's performance in the 18 months before the 1929 market crash.

But think again before you go on any selling binge, says Mark Hulbert, editor of the Hulbert Financial Digest.

"The chart's statistical validity is questionable, at best. Even many of those who insist it is worth paying attention to aren't predicting a crash," he wrote in The Wall Street Journal.

Editor’s Note: 5 Reasons Stocks Will Collapse . . .

Tom McClellan, editor of the investment newsletter the McClellan Report, noted that the Sept. 3, 1929, stock market top coincides with Jan. 14, 2014, Hulbert said.

But David Leinweber, founder of the Center for Innovative Financial Technology at the Lawrence Berkeley National Laboratory, is skeptical. "If you looked at enough periods of the same length, you'd find all sorts of very similar pictures, most without a crash at the end," he told Hulbert.

This kind of chart amounts to "data mining," searching for a statistical pattern until you find one, Leinweber said.

University of Pennsylvania finance professor Jeremy Siegel is one market expert who doesn't think a crash is coming. Indeed, he sees further gains ahead for stocks, thanks to buoyant economic growth and earnings.

"My fair value on the Dow is 18,000," he told CNBC. That would represent a 12.4 percent rise from the Dow's close of 16,020 Friday.

Editor’s Note: 5 Reasons Stocks Will Collapse . . .

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