BlackRock remains convinced the stock market has further to run, the chairman and CEO of the world's largest money manager told CNBC on Friday.

We're "quite bullish," Larry Fink said in a "Squawk Box" interview

"We believe the U.S. economy and the global synchronized, global economies are strong enough to continue the upward bias on equities," he said.

He also believes that "investors are underinvested," which means he thinks there's more money on the sidelines that could come into the market.

"The demand in credit and other assets is going to keep a spike in interest rates to be more muted," Fink said.

"We think interest rates are going to be higher," he added. "We don't think this is necessarily bad."

Retirement savers even as old as 50 should mostly be in stocks rather than bonds, he said.

Fink also said the Republican tax overhaul law is largely going to help Americans, and should add about 1 percent annually to economic growth, at least in the first few years.

Meanwhile, the U.S. corporate tax cut is a problem for Mexico because the rate is now lower in America, Fink said. Companies that had domiciled in Mexico for tax reasons are going to make their new tax homes in the U.S., he predicts.

BlackRock said Friday morning its assets under management surpassed $6 trillion in the fourth quarter. It reported better-than-expected quarterly earnings and revenue.