Longtime stock bull Jeremy Siegel told CNBC on Tuesday that he sees favorable market trends—including the prospect for solid economic growth with low inflation—that could send the Dow Jones Industrial Average past the 20,000 level by the end 2015.
"There are a number of goods things, I think, that need to happen, but certainly that would be even conservative for fair market value if we get some of these favorable trends coming together over this next year," the Wharton School finance professor said on "Squawk Box."
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He cited economic growth of 3 percent to 4 percent, low inflation, cheap gas prices and an improving job market as some of the factors that could help push stocks higher.
But he said, "The 3 percent [GDP], that's the wild card." He cautioned that many forecasters are calling for growth of 2 percent to 2.5 percent in the fourth quarter.
During the October selloff, Siegel had started to waver a bit on whether his prediction of Dow 18,000 by year-end would come to pass. But with the market back on track, he told CNBC earlier this month that he's again confident that blue chips would reach that level after all.
In a lackluster session Monday, the eked out its 42nd new high of 2014. The index has moved less than one-tenth of a percent in each of the last five sessions, and the Dow has only had one triple-digit point move this month after having 16 in October.
The S&P was up almost 10.5 percent for the year as of Monday's close. The Dow was up about 6.5 percent in 2014.
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"Two to three years ago, I thought we were really undervalued given interest rates and earnings," Siegel told "Squawk Box" on Tuesday. "I thought the bullish calls were really easy to make. I still think we are 10 percent undervalued given the interest rate structure."
Siegel said he'd view the Dow between 19,000 and 19,500 as fair value.
While Siegel kept preaching his bullish message, other market watchers including Carl Icahn are less optimistic. At a Reuters investment summit Monday, the billionaire of a "major correction" in the next few years.