The latest unexpected new tariffs from Donald Trump are sending a chill through Chinese tech stocks on this last trading day of the week.

The U.S. president surprised many when he announced he would levy 10% tariffs Sept. 1 on an additional $300 billion a year of Chinese imports, saying progress was moving too slowly in talks with Beijing for a trade deal. Trump is already well-known for his unpredictability, but that’s little comfort for companies caught in the middle of the trade war, including China’s top tech names. 

In Hong Kong, social networking titan Tencent was down 2.6% in mid-morning Friday trade, while online-to-offline services leader Meituan Dianping was down 3.6% — outpacing a 2.2% decline for the broader Hang Seng Index. Struggling smartphone maker Xiaomi was down a milder 1.7%, but that was enough to push it to a fresh all-time low since its Hong Kong IPO a year ago.

The Shanghai Composite Index was faring slightly better, down 1.5% mid-morning.

The declines followed similar weakness for the big Chinese tech names on Wall Street on Thursday after Trump’s latest surprise. Shares of e-commerce leaders Alibaba and JD.com both sagged more than 4%, while struggling search giant Baidu finished down 2.2%.

Related: Trump Expands China Trade War to Cover Additional $300 Billion