A day after recording its largest single-day gain in history, the Dow Jones Industrial Average fell more than 600 points in Thursday afternoon trading — the latest measure of the market’s continued unpredictability.

Wavering in the red for most of the day, the Dow eventually closed up 258 points, or 1.13 percent, to 23,136. Yesterday it surged 1,086 points, marking the Dow’s biggest-ever post-Christmas increase as well as the highest daily percentage gain for all benchmark indexes since 2009.

Wall Street appeared to react to renewed tensions between the United States and China, following an exclusive Reuters report that President Donald Trump is considering an executive order that would prohibit U.S. companies from using equipment made by Chinese telecom giants Huawei and ZTE. (The news agency cited three sources familiar with the matter.)

The Trump administration has claimed that Huawei and ZTE work for the Chinese government, using their devices to spy on American corporations and consumers.

The order, which would come in the new year, could put a strain on the current financial ceasefire between Washington and Beijing as the leaders of the world’s two largest economies negotiate a permanent trade deal.

At the G20 summit early this month, Trump agreed to forgo a 25 percent hike in tariffs on $200 billion worth of Chinese goods, initially scheduled to take effect on Jan. 1.

Instead, the 10 percent tariff was kept in place as the countries resume talks that also address China’s alleged forced technology transfers and cybercrimes. (That same week, the stock market nosedived after the arrest of Huawei CFO Meng Wanzhou in Canada at the behest of the U.S.)

Investors remain wary following weeks of tumultuous trading and concerns over global economic growth. U.S. stocks have taken a major hit this month, suffering their worst week of trading since the 2008 financial crisis.

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