"Policy has proven to be disappointing so far. I think if we get tax reform, which I think we're going to get fourth quarter or the first quarter … I think the market will see another leg up," Fink said Tuesday on CNBC's "Squawk Box." "If we did not get tax reform, we would have a market setback."
The S&P 500 has rallied 20 percent since the Nov. 8 election through Monday.
Fink, who oversees $5.7 trillion as head of the world's largest money manager, explained why he thinks the market will drop if the legislation doesn't go forward.
"That would really disprove if we can get anything done in Washington. It would put a real negative psychology onto the U.S. markets," he said.
Fink appeared from Riyadh, from the sidelines of the Future Investment Initiative, a conference presented by Saudi Arabia's sovereign wealth fund.