Actor Mark Ruffalo has penned an op-ed in The New York Times claiming that Hollywood stars will not sign an open letter opposing the Paramount-Warner Bros. merger out of fear of being blacklisted. 

The open letter, which has amassed over 4,000 signatures from filmmakers and actors, including 75 Oscar winners, urges US regulators to block the merger on claims that it would reduce industry competition, effectively creating a monopoly, Variety reported.

“The most revealing thing about that letter wasn’t the people who signed it. It was the people who didn’t. Not because they disagreed— because they were afraid,” Ruffalo wrote in the op-ed, along with co-writer Matt Stoller, the research director at American Economic Liberties Project. “There are many reasons to block this deal, but we now believe the most fundamental one is what we encountered when asking artists to use their voices: fear. A deep, ugly and pervasive fear of speaking out.”

Ruffalo explained that some industry professionals who have shown opposition to the merger have already been blacklisted, saying that artists’ fear of not wanting to sign the letter “is not unjustified.” 

“This merger will cause many harms in Hollywood, but one is already in effect: People are afraid to say what they think about their own industry,” Ruffalo wrote. The deal is still pending approval by regulators in the US and Europe.

The open letter uploaded to the website BlockTheMerger.com reads: “As filmmakers, documentarians and professionals across the movie and television industry, we write to express our unequivocal opposition to the proposed Paramount-Warner Bros. Discovery merger. This transaction would further consolidate an already concentrated media landscape, reducing competition at a moment when our industries— and the audiences we serve — can least afford it.”

“The result will be fewer opportunities for creators, fewer jobs across the production ecosystem, higher costs, and less choice for audiences in the United States and around the world. Alarmingly, this merger would reduce the number of major US film studios to just four,” the letter continues.

Ruffalo and Stoller urged Hollywood to unite in defiance of the merger. “We’ve seen what happens when monopoly-leaning companies benefit from a fear that silences dissent,” the pair wrote in their conclusion. “If we can defeat the oligarchs trying to seize control of our TV shows and movies, maybe we can do it elsewhere, too.”