Back in 2010, Natalie Portman and Ashton Kutcher co-starred in No Strings Attached. Both received top billing as pals who embark on a "casual" relationship, but according to Portman, 35, she earned three times less than Kutcher for the film.
During an interview with Marie Claire UK, Portman (on a promotional tour for Jackie, which is expected to land her an Oscar nomination) told the magazine she knew that Kutcher, 38, made more money than her, but she didn't speak out at the time.
"I wasn't as pissed as I should have been," Portman said. "I mean, we get paid a lot, so it's hard to complain, but the disparity is crazy."
Representatives for Kutcher did not return a request for comment.
An increasing number of stars are talking publicly about the gender pay gap.
Gillian Anderson has revealed she was offered half of what David Duchovny made on The X-Files and, in 2015, Jennifer Lawrence wrote an essay in Lena Dunham's Lenny newsletter about what it was like to find out that all her male co-stars in American Hustle made a higher salary than her. However, since she had already made so much money on the Hunger Games and X-Men films, she apparently felt guilty asking for more.
"I didn't want to keep fighting over millions of dollars that, frankly, due to two franchises, I don't need," Lawrence wrote. "But ... there was an element of wanting to be liked that influenced my decision to close the deal without a real fight. I didn't want to seem 'difficult' or 'spoiled."'
Portman also told Marie Claire that compared to other professions, where women routinely make 80 cents to the dollar compared to men, Hollywood actresses make 30 cents on the dollar. Sometimes Hollywood business practices lead to this disparity, such as the one between her and Kutcher.
"I ... went along with it because there's this thing with 'quotes' in Hollywood," she explained. "His was three times higher than mine so they said he should get three times more."
An actor's "quote" is how much they were paid on their previous projects, and dictates how much they make on other films. So if Kutcher already had a higher quote, then he would have made more, just by showbiz standards.
When No Strings Attached came out in January 2011, Portman was about a month away from winning her first Oscar for the ballet drama Black Swan, though she had earned fame in movies like V for Vendetta and through roles in the Star Wars franchise.
Meanwhile, Kutcher - best known for sitcom That '70s show and movies such as Dude, Where's My Car? - was close to a deal in May 2011 for a reportedly massive US$750,000-per-episode salary to replace Charlie Sheen in Two and a Half Men.
Of course, another issue at hand is opportunity: If there are fewer roles for women, they have less of a chance to increase their own quotes. In 2014, a study from the Annenberg School at University of Southern California found that just 28 per cent of characters in the year's top 100 movies were women.
"I don't think women and men are more or less capable. We just have a clear issue with women not having opportunities," Portman said. "We need to be part of the solution, not perpetuating the problem."