December futures slid as much as 1 percent on the S&P 500 Index and were trading 0.3 percent lower by 8:20 a.m. in London on Monday after China summoned the U.S. ambassador following the arrest of Huawei Technologies Co.’s chief financial officer. Futures on the Nasdaq 100 Index and Dow Jones Industrial Average both declined as much as 1.1 percent. Data on Sunday showed China’s producer prices climbed at the slowest pace in more than two years.

“What’s worrying people is the expectation of a slowdown in both European and U.S. growth in 2019, coupled with a lack of clarity on trade and the effectiveness of any China stimulus,” said John Roe, head of multi-asset funds at Legal & General Investment Management Ltd.

Futures slid even as President Donald Trump’s trade team sought to insulate talks with China from a growing dispute over the U.S. pursuit of a Huawei executive on Sunday. Financial markets remained concerned that a fragile truce with Beijing at a Group-of-20 meeting earlier this month was at risk.

The Stoxx Europe 600 Index opened 0.7 percent lower, led by a drop in chemicals and automakers. The FTSE 100 Index of U.K. stocks outperformed as a top European Union court said the country can unilaterally reverse the Brexit process. The ruling from EU Court of Justice in Luxembourg comes as U.K. Prime Minister Theresa May must decide whether to put her Brexit deal to a vote in Parliament this week and risk a humiliating defeat.

Trade-war anxiety plus uncertainty over U.S. interest rate policy drove the S&P 500 down 4.6 percent last week, the biggest decline since March, as the gauge slipped back into negative territory for the year.

“It’s clear this is a growth scare based sell-off with yields down. So the market concern is no longer the worry that higher yields from Fed hikes could undermine equities,” said Roe of Legal & General.

Signs that demand remains sluggish in the world’s second-largest economy came on the heels of data showing the U.S. labor market moderated in November. It’s emboldening those who are betting on a slower pace of Federal Reserve interest-rate increases next year.

“Investors are trying to assess how quickly policy makers will respond to the latest signals from the economic data,” said Andrew Milligan, head of global strategy at Aberdeen Standard Investments. “Surveys of investor opinion show that many are worried but not unduly concerned by recent economic and political developments.'