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Treasury Secretary Steven Mnuchin, one of President Donald Trump's key negotiators in the U.S.-China trade talks, has pushed Beijing to grant the American film industry greater access to its markets.

But now, Mnuchin’s ties to Hollywood are raising ethical questions about his role in those negotiations. Mnuchin had been a producer in a raft of successful films prior to joining the Trump administration.

In 2017, he divested his stake in a film production company after joining the White House. But he sold that position to his wife, filmmaker and actress Louise Linton, for between $1 million and $2 million, the Center for Public Integrity reported this month. At the time, Linton was his fiancée.

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That company, StormChaser Partners, helped produce the mega-hit movie “Wonder Woman,” which grossed $90 million in China, according to the Times. Yet, because of China’s restrictions on foreign films, the producers received a small portion of that money. Mnuchin has been personally engaged in trying to ease those rules, which could be a boon to the industry, according to the Times.

Mnuchin’s 2018 disclosure, which was obtained by the Times, shows StormChaser listed as one of Linton’s assets. Because the couple is now married, the asset is considered Mnuchin’s. And he is owed that same $1 million to $2 million, with additional interest, from the company in 2026, the 2018 form disclosed.

Senate Democrats on Thursday questioned Mnuchin about his financial holdings. He responded during the hearing that he has complied with rules of career ethics officials inside the Treasury Department, but declined to discuss details of the transaction.

“I am advised by people at Treasury that I am fully in compliance and I have no ethical issues,” Mnuchin said at the hearing. The Office of Government Ethics has not yet certified his 2018 financial disclosure, the first since his marriage to Linton, the Times reported.

Since trade talks began last year, film lobbyists have met with Mnuchin’s top deputies and officials from the Commerce Department and the office of the U.S. Trade Representative. Mnuchin has reportedly been particularly responsive to lobbying from the film industry.

StormChaser did not immediately respond to CNBC’s request for comment.

A Treasury Department spokesperson said in a statement: “Treasury’s career ethics lawyers certified the Secretary’s financial disclosure on June 27, 2018 and identified no outstanding conflicts of interest. The Secretary is in full compliance with his ethics agreement. We continue to work with the Office of Government Ethics to obtain certification of the disclosure.”