Stocks in Asia Pacific tumbled on Monday as the U.S. Federal Reserve slashed its benchmark interest rate to zero and launched a massive quantitative easing program in an emergency move on Sunday.
The S&P/ASX 200 in Australia led losses among the region's major markets as it dropped 9.7% to close at 5,002. That was its largest ever daily drop, according to Reuters.
The heavily weighted financial subindex dived 11.1% as shares of the Australia's major banks saw steep declines: Australia and New Zealand Banking Group plunged 12.5%, Commonwealth Bank of Australia slipped 10.01%, Westpac fell 11.81% and National Australia Bank plummeted 12.44%.
Mainland Chinese stocks dropped on the day as well, with the Shanghai composite 3.4% lower at about 2,789.25 while the Shenzhen composite slipped 4.834% to approximately 1,712.02. The Shenzhen component plunged 5.34% to 10,253.28.
Hong Kong's Hang Seng index also fell 4.38%, as of its final hour of trading.
Overall, the MSCI Asia ex-Japan index declined 4.99%.
Investors watched for market reaction to the Fed's latest actions. The new fed funds rate, used as a benchmark both for short-term lending for financial institutions and as a peg to many consumer rates, will now be targeted at 0%-0.25% down from a target range of 1% to 1.25%.
Following the Fed decision, U.S. stock futures fell sharply. Stock market futures hit "limit down" levels of 5% lower, a move made by the CME futures exchange to reduce panic in markets. No prices can trade below that threshold, only at higher prices than that down 5% limit.
"This isn't stimulus, this is ... activity that prevents a meltdown, in a way," Daniel Gerard, senior multi-asset strategist at State Street Global Markets, told CNBC's "Squawk Box" on Monday. "That's the goal here, the Fed coming out so strong is to prevent a crisis."
"Despite whipping out the big guns (and jumping the gun) the Fed appears to lack the silver bullets; falling short of being the decisive backstop for markets," Vishnu Varathan, head of economics and strategy at Mizuho Bank, wrote in a note.
"Ironically, markets might have perceived the Fed's response as panic, feeding into its own fears; especially as COVID-19 cases spike globally, prompting harder border controls," said Varathan.
Following the Fed's announcement, the Bank of Japan announced on Monday steps such as the "active" purchase of exchange-traded funds and Japan real estate investment trusts to "contribute to supporting economic and financial activities."
The Japanese yen, often viewed as a safe-haven currency in times of economic uncertainty, traded at 106.31 per dollar from lows around 108 seen late last week.
That comes as officials around the world raced to implement measures to combat the economic impact of the ongoing global coronavirus outbreak. For its part, the Fed said "the coronavirus outbreak has harmed communities and disrupted economic activity in many countries, including the United States."
Oil prices dropped in the afternoon of Asian trading hours on Monday, with international benchmark Brent crude futures down 5.97% to $31.83 per barrel. U.S. crude futures also slipped 4.19% to $30.40 per barrel.
On the economic data front, China said Monday the national urban survey unemployment rate hit 6.2% in February. That's the highest on record based on data accessed through Wind Information. The unemployment rate was 5.7% in February for 31 major Chinese cities, the National Bureau of Statistics said Monday.
Fixed asset investment plunged 24.5% in the first two months of the year from a year ago, the bureau said. Investment in manufacturing was the hardest hit, down 31.5%. Investment in high-tech was down 17.9%, the bureau said.
The Chinese government has taken measures to curb the coronavirus' spread in the country, including the extension of the Lunar New Year holiday that left factories shuttered for a prolonged period.
The U.S. dollar index, which tracks the greenback against a basket of its peers, was last at 98.216 after rising from levels below 96 last week.
The Australian dollar changed hands at $0.6143 after slipping from levels above $0.64 last week.
— CNBC's Fred Imbert ,Steve Liesman and Evelyn Cheng contributed to this report.