Jamie Dornan and Dakota Johnson are expected to negotiate seven-figure pay rises for the two Fifty Shades of Grey sequels.
Read more: Movie review: Fifty Shades of Grey
The co-stars were reportedly paid US$250,000 each (NZ$347,000) plus bonuses for the movie, which became the highest-grossing 18-rated film in UK box office history after just 10 days of release.
As the film approaches $550 million in cinemas worldwide, the actors will be looking to up their salary, according to the Hollywood Reporter.
Producer Dana Brunetti told the magazine he was looking to keep the first installment's $40 million budget from skyrocketing because of their pay.
"That was the great thing about this film - we knew we were going to be able to make stars," he said.
"Now it's their opportunity to get paid on other projects. It's been a breakout role for both of them. I'm sure they are getting tons of offers on other things."
Both Johnson, 25 and Dornan, 32, are believed to have signed multiple film contracts to cover sequels based on EL James' bestselling erotic novels Fifty Shades Darker and Fifty Shades Freed.
Jennifer Lawrence's rumoured $10 million for the second Hunger Games film, Catching Fire, could be taken as an example of the deals that can be stuck.
Dornan is expected to return to British television screens in the recently announced third series of The Fall, the crime drama that launched his acting career.
He will also star in upcoming films The 9th Life of Louis Drax and wartime drama Anthropoid.
Johnson, who is the daughter of actors Don Johnson and Melanie Griffith, will play a homeless woman in Chloe and Theo and then star alongside Johnny Depp and Benedict Cumberbatch in crime drama Black Mass.