The major futures indexes suggest a slight decline on the Dow and a gain of 0.4% on the Nasdaq.
Powell will deliver the Fed's semiannual report to Congress on the economy. Investors will be listening for hints on monetary policy related to rising inflation. Central bank officials have said that they believe pricing pressures will be short-lived.
A report on Tuesday showed consumer prices in June rose by the most in 13 years.
The report adding to concerns that the Fed might consider withdrawing its low-interest rate policies and scaling back its bond purchases earlier than expected.
Traders will get another look at inflation when the Bureau of Labor Statistics reports wholesale price data for June. Headline PPI is expected to increase 0.6% month-over-month according to Refinitiv forecasts, slightly lagging May’s 0.8% rise. Year-over-year, prices paid by wholesalers are anticipated to jump 6.8%, up a notch from 6.6% in May.
The parade of financial-sector earnings continues Wednesday with Bank of America, Wells Fargo, Citigroup, BlackRock and PNC Financial Services all posting ahead of the opening bell.
In Europe, London's FTSE declined 0.6%, Germany's DAX is off 0.2% and France's CAC slipped 0.3%.
In Asia, Japan's benchmark Nikkei 225 edged down 0.4%, Hong Kong's Hang Seng dropped 0.6% and China's Shanghai Composite dipped nearly 1.1%.
Some parts of Japan are also seeing an uptick in COVID-19 infections, fanning fears about the tens of thousands of athletes, dignitaries and other people from some 200 nations entering the country for the Tokyo Olympics.
On Tuesday, the S&P 500 fell 0.4%, with most of the companies in the benchmark index losing ground.
The pullback brought the major stock indexes slightly below the record highs they set a day earlier.
The Dow Jones Industrial Average dropped 0.3% to 34,888.79. The tech-heavy Nasdaq slid 0.4% to 14,677.65.
Goldman Sachs fell 1.2% despite reporting the second-best quarterly profit in the investment bank's history. JPMorgan Chase dropped 1.5% after giving investors a mixed report with solid profits but lower revenue as interest rates fell over the last three months.
Bond yields slipped to 1.40% from 1.42% late Tuesday. Overall, yields have been trending lower after a sharp spike earlier in the year.
In energy trading, benchmark U.S. crude lost 43 cents to $74.83 a barrel in electronic trading on the New York Mercantile Exchange. It picked up $1.15 to $75.25 on Tuesday. Brent crude, the international standard, gave up 44 cents to $76.05 a barrel.
The Associated Press contributed to this report.