President Trump announced tariffs on Chinese imports Thursday, reigniting fears of a trade war and sending jitters through the the stock market.

“Even though this has been out there, the big worry is what’s the next shoe to drop,” said Daniel Ives, Chief Strategy Officer at GBH Insights.

The tariffs are aimed at curbing what Trump calls “a tremendous intellectual property theft problem.”

U.S. Trade Representative Robert Lighthizer now has 15 days to identify $50 billion worth of imports to tax, with a focus on technology products.

Many experts and investors fear that China will retaliate, impacting companies like Boeing that have carved large markets in China.

This move comes shortly after Trump levied taxes on imported steel and aluminium, angering allies around the world, including Canada and the EU.

Lighthizer signaled on Thursday that most of those allies will now be exempt from the metals tariffs, seeming to send a clear signal that much of Trump’s protectionist policies are squarely crafted with China in mind.

Overall, Chinese companies may have more to lose from these recent IP tariffs than U.S. tech companies, said Ives. He pointed out that, other than Amazon, revenue from China is negligible for most companies.

In addition to the tariff news, the markets were still reacting to Facebook’s privacy scandal.

The social media giant “continues to be that dark cloud over tech stocks,” said Ives.

“[It’s] been a lot of angst amongst investors we’ve been talking to.”