Santelli Extra: This should keep bulls up at night

In a Santelli Extra interview exclusive to CNBC Pro subscribers, Wells Capital strategist Jim Paulsen said there's something going on in the U.S. economy that poses a big risk to investors for the years ahead.

This is not stopping the longtime bull from predicting a new record high in the stock market this year, but it has him worried about the long term.

This metric "paints a very cautious, if not ugly picture, for the next several years of what we can expect in terms of productivity and what that means for overall economic growth and also what it means for the stock market performance," Paulsen said.

Watch the full interview below to find out what that is.