Investors in Hollywood’s top studios and streaming services were spooked Monday after President Donald Trump proposed implementing a 100% tariff on movies made overseas.

Shares of Netflix, Disney, Paramount and Warner Bros. Discovery fell ahead of the opening bell, with Comcast-owned Universal also trading slightly down. Here’s how those share moves shook out:

• Netflix down more than 5%
• Disney down more than 3%
• WBD down more than 3%
• Paramount down more than 2%
• Comcast down less than 1%

Trump called tax incentives offered by foreign countries “a national security threat” in a post on Truth Social Sunday night. He said he was authorizing the Department of Commerce to impose a levy on all films produced abroad that are sent to the United States.

How Trump intends to implement these duties is unclear, as is exactly who is being targeted and who would foot that potential tariff bill.

Hollywood studios have long filmed movies overseas, either for tax benefits or to capture the natural setting of international locations. Some films are shot in multiple countries, with many studios having satellite production hubs around the globe.