Long-time bull Jeremy Siegel sees risks that could undermine the 2019 market rally.
The U.S.-China trade war and slower-than-expected earnings growth are giving him an uncharacteristically muted view on the market's strength.
"I'm not predicting a big rally," the Wharton finance professor said Monday on CNBC's "Trading Nation." "We've got a slight tilt upward, but no huge bull push."
Siegel, known for predicting market milestones including Dow 20,000 to Dow 25,000, has been moving away from his bull stance. Last September, he told "Trading Nation" that correction risks were growing and 2019 could be a rough year.
In a note to CNBC on Monday, he said the "market is counting on a China deal; if not, expect a big sell-off." It's the most ominous risk to his base case, albeit the least likely to happen.
"We've got an 80 to 90 percent probability of a favorable outcome really baked in," Siegel said. "One of the strongest things [President Donald] Trump has going for him is the economy, and the stock market. And, going into an election year, he doesn't want that to falter."
Siegel is also concerned about first-quarter earnings, which kick off April 12 with JPMorgan Chase's results.
"Earnings estimates might be more challenged this year than a lot of analysts think," he said, alluding to the bearish impact of a higher dollar and last year's big increase in margins. "[It] is not the cheap market that we certainly had last December."
His most-likely scenario: The Dow and will rise another 5 to 6 percent from current levels by year-end with volatility ticking higher.
"We're only a couple percent away from the all-time high reached last September," Siegel said. "It does look like we might push above."
Both indexes are 2.5 percent away from their record highs.