"The danger is that … Powell is disappointing the markets and is nowhere near as informal as the street hopes," Jeffrey Halley, senior market analyst in Asia Pacific for Oanda, wrote in a research note Friday.
China's yuan also plummeted on Friday. The People's Bank of China set the daily reference rate for the currency at 7.0572 against the US dollar, the lowest since March 2008.
The markets are in a state of "currency war detention," wrote Stephen Innes, managing partner at Valor Markets, in a research note, but he added that the yuan's weakening indicates that China's central bank "may be putting one of  cards on the table. "
" These are not the cheerful signals for risk terms in my view, "added Innes.
CNN Business & # 39; Donna Borak contributed to the story.