Larry Fink, CEO of BlackRock, the largest asset manager in the world, said Wednesday his biggest fear for the market is a policy mistake from the Fed.
"People are assuming another tightening this year and another three next year. Could we see an inverted yield curve like next year [or] early 2019?" Fink told CNBC's "Squawk Box." "We want to avoid an inverted yield curve."
An inverted yield curve shows short-term interest rates higher than long-term rates.
Equities have been on a stellar run this year. The three major indexes have reached all-time highs and are all up more than 10 percent in 2017. Recently, they have been lifted by solid economic data and renewed hopes of tax reform.
President Donald Trump tweeted about the stock market Wednesday, saying it would grow "by leaps and bounds" if tax reform were accomplished.
Wall Street also looked to corporate news on Wednesday, as earnings season picked up steam. BlackRock and Delta Air Lines both reported quarterly results that beat expectations.
Nick Raich, CEO of The Earnings Scout, said the average earnings and sales growth rates for the 26 S&P 500 companies that had reported as of Wednesday morning were 14.9 percent and 10 percent, respectively.
"Those numbers are probably going to drop once the insurers start reporting, but I think that's going to be a one-time thing" because of the hurricanes, Raich said. Nonetheless, "this is a very solid start to the earnings season. If you want to go bearish, you don't want to look to earnings right now."
Other companies scheduled to report this week include big banks like Citigroup, JPMorgan Chase and Bank of America.
"This year might be the first year in the past six or seven where all the banks focus on growth and not cost-cutting," said Wei Ke, head of the North American financial services practice at Simon-Kucher. "What I've seen this year is banks having cut most of the costs they could cut."