Treasury yields have retreated sharply from their highs amid expectations that the Fed has reached the end of its rate-hike campaign, helping the S&P 500 and the Nasdaq notch their longest streak of gains in two years on Tuesday.

Markets are now pricing in rate cuts as soon as in May, according to the CME Group's FedWatch tool, with odds of a cut of at least 25 basis points having risen to nearly 52%, compared with about 41% a week earlier.

Still, cautious comments from several central bank officials over the past few days have kept investors on edge, with Fed Governor Michelle Bowman flagging the possibility of further rate hikes given the strength of the U.S. economy.

All eyes will be on Powell's opening remarks before the Federal Reserve Division of Research and Statistics Centennial Conference at 9:15 a.m. ET (1415 GMT) for more clues on how long U.S. monetary policy could stay restrictive.

The Fed Chair is also due to speak at another conference on Thursday.

"Stocks may well pause for breath as investors balance the hope for rate cuts with building financial stresses in the economy," Derren Nathan, head of equity research at Hargreaves Lansdown, wrote in a note.

"And it wouldn't be the first time ... that the market has been wrong about the timing of the Fed pivot."

The benchmark U.S. 10-year Treasury yield was steady at 4.5894%, below the 5% level breached in October.

Analysts have mixed views about the outlook for equities towards the end of the year, with some cautiously optimistic about the prospects of a rally, while others have highlighted the likelihood of economic growth concerns and tepid earnings forecasts keeping sentiment subdued.

On the earnings front, Biogen added 1.4% in premarket trading after the drugmaker beat estimates for third-quarter profit.

Under Armour added 1.9% on raising the annual gross margin forecast as the sports apparel maker benefited from cost cuts.

At 7:18 a.m. ET, Dow e-minis were up 2 points, or 0.01%, S&P 500 e-minis were down 1.75 points, or 0.04%, and Nasdaq 100 e-minis were down 15 points, or 0.1%.

Among other movers, electric vehicle maker Rivian Automotive climbed 8.8% in premarket trading after raising its full-year production forecast, while smaller rival Lucid Group fell 5.8% after trimming its production forecast.

Take-Two Interactive Software rose 9.1% on a report stating its Rockstar Games unit plans to announce the next "Grand Theft Auto" game as early as this week.

Shares of Spirit AeroSystems tumbled 13.2% after the embattled aerospace supplier announced new measures to raise capital.