Stocks are at all-time highs. The and Nasdaq were all in record territory Monday morning, as stocks jumped on signs of progress on a NAFTA deal between Mexico and the United States.

"If you're looking at your portfolio, I don't think it's a bad idea to take some gains, especially from some areas of the market that have done best," Tim Courtney, Exencial Wealth Advisors CIO, told CNBC on Friday. "Take some of those gains and have some money set aside that you can use as dry powder if the market pulls back."

"But the problem with doing that with a lot of your assets is you could very well miss," Courtney added.

Here's what five market experts had to say about what investors should do next with stocks hitting record highs.