Global selloffs in stocks and bonds resumed Monday, while commodities slumped amid concern central banks in the world’s biggest economies are questioning the benefits of loose monetary policy.

Shares in Europe and Asia dropped by the most since the aftermath of Britain’s June vote to leave the European Union, and futures foreshadowed declines in U.S. equities. Portuguese debt led losses among euro-area bonds, while yields in Australia and New Zealand climbed to their highest levels of the quarter. Oil sank to about $45 a barrel as nickel tumbled the most in four weeks. The yen strengthened and South Korea’s won tumbled.

Financial markets have been jolted out of a period of calm by an uptick in concern over the outlook for central bank policies. Federal Reserve Bank of Boston President Eric Rosengren spurred bets on an interest-rate hike on Friday, saying the U.S. economy could overheat should policy makers wait too long to tighten. The comments came a day after European Central Bank chief Mario Draghi surprised markets by playing down the prospect of further stimulus. The S&P 500 slumped 2.5 percent Friday, breaking out of a range that hadn’t seen it move more than 1 percent in either direction for 43 days.

“Central banks are reluctant to add additional stimulus and that’s causing a lot of concern,” Niv Dagan, executive director at Peak Asset Management LLC in Melbourne, told Bloomberg Radio. “We expect additional downside in the near term. You want to wait and see and remain cautious,” he said.

Fed Governor Lael Brainard, seen as a leading opponent of rate increases for much of the past year, will speak Monday in the last scheduled appearance by a U.S. central banker before the authority’s self-imposed blackout period running up to the Sept. 20-21 policy meeting. Any hawkish shift in her rhetoric may stoke volatility in financial markets, which on Friday put the probability of a hike in borrowing costs this month at 30 percent.

Stocks

The Stoxx Europe 600 Index slid 1.8 percent as of 8:14 a.m. London time. Linde AG dropped 7.1 percent after it and Praxair Inc. terminated talks to create the world’s largest supplier of industrial gases.

The MSCI Asia Pacific Index slumped 2 percent, led by losses in raw-materials producers. Benchmarks in Australia, Hong Kong, New Zealand and South Korea all sank by more than 2 percent, while markets including Indonesia, Malaysia and Singapore were shut for holidays. A gauge of expected price swings in Hong Kong equities jumped by the most since January and a comparable measure for shares in Japan had its biggest gain in about three months.

“What has changed is the market’s comfort with the assumption that central banks will be providing sufficient liquidity support for a rally,” said Ken Peng, an Asian investment strategist at Citi Private Bank in Hong Kong.

Samsung Electronics Co. plunged 7 percent in Seoul — its biggest loss in four years — after U.S. regulators and the company asked users of its Note 7 smartphones to turn off the devices because of fire risk. BHP Billiton Ltd., the world’s biggest mining company, fell 4 percent in Sydney.

Futures on the S&P 500 Index were down 0.7 percent after the underlying measure sank 2.5 percent on Friday.

Bonds

Portugal’s 10-year bond yield increased six basis points to 3.22 percent, while Germany’s climbed three basis points to 0.04 percent. The rate on similar-maturity notes in Australia surged nine basis points to 2.05 percent, after gaining 10 basis points on Friday, and that for New Zealand jumped 11 basis points to 2.47 percent.

Yields on benchmark Treasuries were little changed at 1.67 percent, after rising eight basis points in the last session.

Japanese government bonds with maturities of less than a decade advanced and longer-dated securities declined. The moves follow a Reuters report on Friday that said the Bank of Japan was studying options to steepen the nation’s yield curve.

The cost of borrowing yuan in Hong Kong’s interbank market jumped, with the three-month rate climbing 95 basis points to 4.21 percent, the highest since March. The rates surged last week amid speculation the People’s Bank of China was tightening the offshore supply of its currency to deter bets on deprecation. Twelve-month non-deliverable forwards indicate traders are the most bearish they’ve been on the yuan in almost four months.

Commodities

The Bloomberg Commodity Index fell 0.7 percent, after sliding 1.3 percent on Friday.

Crude oil sank 1.7 percent to $45.10 a barrel in New York after American producers increased drilling, adding to a glut. U.S. rigs targeting crude rose to the highest since February, according to data from Baker Hughes Inc.

Nickel slid 3.5 percent in London, dropping for the first time in eight days, while tin tumbled by the most since May. Gold rose 0.2 percent, after retreating 1.6 percent over the last three sessions.

Iron ore fell in China to the lowest since June amid speculation the nation’s policy makers will tighten property curbs and so cool demand for steel. Steps should be taken to restrain bubble-like expansion in the housing market, Ma Jun, chief economist of the PBOC’s research bureau, said in an interview with China Business News.

Wheat in Chicago fell 0.7 percent to about $4 a bushel, approaching a decade-low of $3.8675 reached on Aug. 31. Money managers have their biggest-ever bet on price declines and a global stockpile estimate by the U.S. Department of Agriculture is forecast to still be at a record high after the figure is updated on Monday.

Currencies

The Bloomberg Dollar Spot Index fluctuated near a one-week high before Brainard’s speech, with regional Fed chiefs for Atlanta and Minneapolis also lined up to speak on Monday. The yen appreciated 0.5 percent versus the greenback.

There’s “growing caution over a rate hike as the day of the Fed’s decision draws closer,” said Masashi Murata, a currency strategist at Brown Brothers Harriman & Co. in Tokyo. “Markets had been too confident that a hike wouldn’t happen. But global economies are not in a critical phase, so there’s a limit to selling on risk aversion. Money will eventually seek yields and underpin high-yielding currencies.”

The won slumped 1.4 percent, the worst performance among major currencies, after Yonhap News reported that U.S. and South Korean intelligence authorities see a high chance that North Korea will conduct an additional nuclear weapons test after holding one on Friday.

Source: Bloomberg