On Wednesday US President Donald Trump lambasted the US Federal Reserve once again, complaining that the Fed has gone "crazy", but the president also reversed tack and called the current stock market sell-off a "correction", one that the administration has been "waiting for".
Powell's goal is to extend the second-longest US economic expansion on record by moving interest rates up just quickly enough to prevent overheating, but not so rapidly that the central bank chokes off growth.
North American markets tracked lower in mid-day trading on Thursday, continuing the previous day's broad-based sell-off that extended into Europe and Asia.
"Our course is clear: Resolutely conduct policy consistent with the FOMC's symmetric 2 percent inflation objective, and stand ready to act with authority if expectations drift materially up or down", Powell said last week, referring to the policy-making Federal Open Market Committee.
Taipei and the Shenzhen Composite Index - which tracks stocks on China's second exchange - were both down around 6%.
The Dow dropped more than 800 points in one of the worst sell-offs since February as investors anxious that sharply rising rates would constrain the nation's historic economic expansion.
US President Donald Trump speaks during a briefing on Hurricane Michael in the Oval Office of the White House in Washington, DC, October 10, 2018. "It's so tight. I think the Fed has gone insane", Trump told reporters as he arrived for a campaign rally ahead of the U.S. mid-term elections.
During an event earlier Wednesday amid the sell-off, Trump and his top economic adviser, Larry Kudlow, said they believed the US economy was strong.
Hurricane Michael set to be strongest storm to ever hit Florida Panhandle
The National Weather Service office in Tallahassee issued a dramatic appeal for people to comply with evacuation orders. The National Hurricane Center predicts Michael will stay a powerful and unsafe rainmaker as it moves across the U.S.
Trump has repeatedly touted Wall Street records as proof of the success of his economic programme, including his confrontational trade strategy.
After a roller coaster ride Thursday, the Dow lost another 545 points for a drop of more than two per cent. London also lost almost two per cent, Frankfurt fell 1.5 per cent, and Tokyo plunged almost four per cent.
"It is clearly a necessary development for economies that are showing much improved growth, with inflation picking up and unemployment being extremely low", she said.
The rout in USA shares followed substantial losses on European stock exchanges, due in part to tensions between Brussels and Rome over Italian budget plans that have revived fears about the eurozone.
Shares on London's FTSE 100 index were down 1.4% in opening trade, while the Frankfurt DAX dropped 1.3% and the Paris CAC shed 1.5%. Many observers expected that would trigger a sell-off in the stock market as investors flooded their cash into Treasurys. And tech stocks got hit particularly hard.
But the Federal Reserve has been gradually raising its interest rates since 2015, bringing the target for its benchmark rate to a range of 2% to 2.25% last month.
Tokyo's Nikkei 225 index plunged 915 points (3.9%) to end at 22,591, while the Hang Seng index in Hong Kong had tumbled nearly 4% in late trade.
Lagarde's comments came as a global market sell-off rolled on following Trump's comments, underscoring rising financial volatility that the International Monetary Fund will address at its annual meetings this week in Bali. It was the sharpest drop in eight months.