If you thought the Dow Jones industrial average having its best day since early May would make longtime market bull Jeremy Siegel more confident in his Dow 20,000 prediction think again.
"I still think Dow 20,000 is possible by the end of the year," the Wharton School finance professor told CNBC's "Closing Bell" in an interview Monday. "But the next six to eight weeks are going to be very rough."
Making the case that the market will face continued, disappointing earnings and the possibility of a September Federal Reserve rate hike, Siegel predicted, "We might be forming a basis for a correction in the next five, six, seven weeks ahead of the Fed action."
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Though about four years have passed since the market last saw a correction, Siegel stopped short of saying that made him believe the market was overdue for one. Instead, he pointed to the combination of cheap oil, a stronger dollar and potentially the first U.S. central bank rate hike in nine years that could bring about a short-term selloff.
However, Siegel discouraged investors from trying to time the market, saying returned stability in oil and a slight depreciation of the dollar could bring the market roaring back to close the year.
"I certainly still am bullish in the long run," he said. "I think after the Fed moves—and I do think they are going to move in September—and the world doesn't end and people look around and say 'we're still standing' that we could have a nice rally in the fourth quarter."
The Dow ended Monday with its first 200-point gain since July as the energy sector was among the leaders of the day on the back of a rally in crude.