U.S. President Donald Trump’s address to the United Nations General Assembly helped knock $56 billion off the value of some of the biggest technology companies.

The combined market cap of FAANG stocks -- made up of Facebook Inc., Amazon.com Inc., Apple Inc., Netflix Inc., and Google parent Alphabet Inc. -- tumbled after Trump made negative remarks about the growing power of social media platforms, a signal to some investors that the industry could soon face extra scrutiny from federal antitrust regulators.

“It’s a reminder that this is a risk they’ve never had before and you have to take that into account from a valuation standpoint,” said Tom Essaye, a former Merrill Lynch trader who founded “The Sevens Report” newsletter. “The president has a belief that social media companies are extremely powerful and not particularly favorable to his policies or potentially his point of view.”

In his speech, which also touched on U.S.-China trade tension, Trump said that social media platforms are acquiring “immense power” and that “a free society cannot allow social media giants to silence the voices of the people.”

Facebook and Amazon were both down more than 2.5% as of 1:22 p.m. in New York for their worst days since August. Netflix fell 4.4% and Microsoft dropped 1.5%.

The tech-heavy Nasdaq Composite Index fell the most of the major equity indexes, sinking 1.7%. That brought the gauge below its 50-day moving average and right up against measure’s 100-day moving average, technical levels that have provided both resistance and support through August.

This article provided by Bloomberg News.