The Dow Jones Industrial Average declined 381 points, or 1.5%, to 25,029, the S&P 500 lost 30 points, or 1.11%, to 2,714 and the Nasdaq Composite dropped 57 points, or 0.78%, to 7,273. For the month, the Dow lost 4.4%, the S&P 500 fell 3.8%, and the Nasdaq lost 1.5%.
Mr Powell signalled the Fed could potentially lift interest rates by more this year to keep the United States economy from overheating, sparking anxiety among share traders.
As a candidate, Trump campaigned on an "America First" trade policy, and a big fear for investors has been that increasingly nationalistic governments will impose barriers that hurt the global economy and trade, as well as profits for US exporters.
Indexes pared their losses as investors questioned how far Trump will end up going, said Brent Schutte, chief investment strategist at Northwestern Mutual Wealth Management. It had only four such days past year.
"The members of the S&P 500 has become quite globalized, and one may argue that most of the things that have benefited this bull market have been globalization-related", Michael O'Rourke, JonesTrading chief market strategist, said by phone. His address to congress signalled the Fed will keep raising interest rates to contain inflation.
Powell told the Senate Finance Committee that he does not see inflation in workers' wages "at a point of acceleration".
The yield on the 10-year Treasury rose to 2.85 per cent from 2.81 per cent late Thursday.More news: Tributes flood in for athletics hero Sir Roger Bannister
Kohl's Corp.(KSS) shares dropped 6.4% after disappointing quarterly earnings. "We are seeing some attempts to undermine this very foundation of the bull market, and it doesn't bode well for S&P 500 companies and their global peers".
Apple gave up $4.65, or 2.6 per cent, to $173.47 and Pfizer shed $1, or 2.7 per cent, to $35.32.
Gold was flat at $1,319.00.
In Europe, Frankfurt's DAX tanked 1.4% and the CAC-40 in Paris dropped 0.8%.
In the commodities markets, benchmark US crude rose 26 cents to settle at $61.25 per barrel. London's FTSE 100 was down 0.7% in afternoon trade.
Excluding one-off charges and adjustments, earnings per share were positive at US$1.26. Brent crude, the worldwide standard, rose 54 cents to $64.37 a barrel.
The dollar fell to 105.54 Japanese yen from 106.24 yen late Thursday.