"The danger is … Powell is frustrating the markets and not as disgusted as the street hopes," Jeffrey Halley, senior market analyst at Asia Pacific for Oanda, wrote in a research note on Friday.
The Chinese yuan also dropped on Friday. The National Bank of China has set its daily reference rate for the currency at 7.0572 against the US dollar, the lowest since March 2008.
Markets are in a state of "currency war", writes Stephen Ines, managing partner at Valuable Markets, in research note. But he added that the slimming of the yuan shows that the central bank of China "possibly puts one of their cards [trade war] on the table."
"I don't think it's the funniest of risk asset alerts," Innes added.
CNN's Business "Donna Borak Contributed to History.