Even if President Donald Trump's tax policies are enacted, the U.S. stock market is still "not a great risk-reward for investors," expert Michael Liss told CNBC on Monday.

That's because as it stands right now, the market is roughly 10 percent overvalued, he noted.

"If you take the pro-growth aspects of President Trump's agenda — so that's lower individual tax rates, lower corporate tax rates and less government regulation — if you were able to implement them instantaneously, we think that corporate profits would be roughly 10 percent higher. Still, that would just get the market to fair value," the senior portfolio manager at American Century Investments said in an interview with "Closing Bell."

The stock market has moved higher since Trump's victory, as investors cheered his promises of tax cuts, deregulation and fiscal stimulus.

However, concerns about how long it will take to enact that agenda are now weighing on the market.

And that focus on policy is going to continue to keep people on edge, said Rebecca Patterson, chief investment officer at Bessemer Trust.

However, economic data are good and improving, and corporate earnings are decent, she told "Closing Bell."

"It's going to be a year of tango. We go two steps forward, one step back," she said. "We still think the equity market ends higher this year but it's going to be a choppy year."