Wall Street stocks finished mixed Thursday as markets weighed more upbeat comments from President Donald Trump on trade with his harsh criticism of Federal Reserve Chair Jerome Powell.

While the Dow finished solidly lower following a big drop in UnitedHealth Group, the other two major indices veered in and out of positive territory in a choppy session.

"The market is cautiously awaiting the announcement of deals" on trade, said Art Hogan of B. Riley Wealth Management, adding that steadier movements in the US Treasury market had "allowed the market to stabilise."

The Dow Jones Industrial Average finished down 1.3 percent at 39,142.23.

The broad-based S&P 500 added 0.1 percent at 5,282.70, while the tech-rich Nasdaq Composite Index declined 0.1 percent to 16,286.45.

"There will be a trade deal, 100 percent," Trump said during a working lunch with Italian Prime Minister Giorgia Meloni.

But Trump ripped into Powell for not lowering interest rates, saying on social media that the Fed Chair's "termination... cannot come fast enough."

The Republican president later said: "I'm not happy with him. I let him know it and if I want him out, he'll be out of there real fast, believe me."

Sources told the Wall Street Journal that Trump has privately discussed firing Powell for months but has not made a final decision, and raised it during private meetings at Mar-a-Lago with former Fed governor Kevin Warsh.

Hogan said a move by Trump to fire Powell would rattle markets and has not been priced in, but added that investors consider that outcome unlikely, and view Trump's comments as "bluster."

Among individual companies, UnitedHealth sank 22.4 percent after significantly cutting its 2025 profit outlook, citing increased costs for health care and a shift in the US government's Medicare program.

But Eli Lilly shot up 14.3 percent after announcing successful clinical tests for orforglipron to treat type 2 diabetes and obesity.

Hertz, meanwhile, surged more than 42 percent after investor Bill Ackman disclosed a stake in the car rental company. (AFP)