The "easy gains" investors saw in 2017 are going to be "harder to come by," top Wall Street strategist Jason Trennert told CNBC on Friday.
"It's going to be hard to repeat this year simply because it was a Goldilocks year, where interest rates still stayed low, the Fed was largely accommodative, earnings were up a lot," the chairman of Strategas Research Partners said in an interview with "Power Lunch."
The market repeatedly notched record highs this year, with the Dow up about 18 percent year to date.
And Trennert doesn't think his thesis necessarily changes if President Donald Trump gets a large part of his agenda passed. While the economy should get a boost, the stock market may still slow down.
"The better the economy does the more liquidity it may suck away from financial assets," Trennert said.
It comes down largely to where the U.S. is in the interest rate cycle, he explained. Plus, the unemployment rate is 4.1 percent.
"If you have a situation where you add a lot of stimulus to an economy that is already at full employment, you may have a situation where bonds actually start to compete with stocks as far as the interests of investors are concerned."
Trennert believes the market's rise this year has much more to do with the rise in earnings, noting that many stocks that would benefit from tax cuts have been weakening since Inauguration Day.