In the medium and long term, Nuveen Asset Management's chief equity strategist Bob Doll is constructive on equities and risk assets.
But he is growing "increasingly cautious" on the market in the short term.
"We think economic sentiment may be too high and elevated confidence may make investors vulnerable to downside economic surprises. To be sure, we are not expecting a significant economic slowdown, but the nearly non-stop pace of positive economic data is unlikely to continue," Doll wrote in a recent note to clients.
He continued: "At some point, a setback will likely be triggered by a manufacturing decline, soft oil prices, weakening data from China or some other factor, which could spark a risk-off phase."
In an interview with CNBC on Thursday, Doll said he doesn't see a substantial pullback in the horizon, but highlighted several recent economic and political developments that give him pause.
Institute for Supply Management published data Monday came in slightly above estimates and declined by a half percent month over month. And Doll noted House Speaker Paul Ryan's comments Wednesday in which he said the House of Representatives, the Senate and the White House "aren't even on the same page yet on tax reform."
An important indicator of economic strength will come on Friday morning, when the Bureau of Labor Statistics releases the March employment report.
As for the markets' performance year to date, Doll said Thursday, "It was big [cap] that led small [cap]. It was growth that led value. It was defensive that led the cyclicals. That isn't where we were last year, nor is it a sign that we're going straight up. It's just a little bit of a warning sign."
Doll typically has a bullish tone. Toward the end of January, as the had risen about 6 percent after the U.S. election in November, he told CNBC's "Squawk Box" that the rally still had room to run. And prior to that, in late November, he told CNBC that the S&P 500 would rise at the end of 2016 and at the end of 2017.
At this juncture, several internal market indicators are giving pause to Chris Verrone, head of technical analysis at Strategas Research Partners.
"This is a market that's really been consolidating for the last four or five weeks now," Verrone commented in an interview Thursday on CNBC's "Trading Nation."
Verrone said that last week about 30 percent of the stocks in the S&P 500 touched 20-day lows, and the market typically offers buyers better opportunities amid "washed-out conditions" when about half of the market hits the same milestone.