While box office takings have dropped off more quickly than expected, falling 70% in the US after the first weekend, there’s no denying that kinky seat-filler Fifty Shades of Grey is a monstrous hit. At $40m (£26.7m), its budget was modest, but it has now made more than $520m worldwide and may even end up taking $600m.

Universal are eagerly eyeing a sequel and the film’s two stars, Jamie Dornan and Dakota Johnson, are looking to share some of the glory. Reports suggest that Dornan and Johnson – who are said to have picked up just $250,000 for the film, albeit with bonuses tied to box office numbers – are looking for a substantial pay rise next time.

The Hollywood Reporter says the pair are seeking a deal similar to the one worked out by Jennifer Lawrence for her role in the Hunger Games franchise. Lawrence received $500,000 for the first film, but after it took $690m worldwide, her pay shot up to $10m.

Fifty Shades producer Dana Brunetti hasn’t spoken about the deal specifically but has suggested that the marketability of each star has soared since the film’s release.

“That was the great thing about this film – we knew we were going to be able to make stars,” he told the Hollywood Reporter. “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.”

The sequel, based on EL James’s first followup Fifty Shades Darker, isn’t expected until late 2016 or early 2017, but Universal has a lot to contend with before production starts. As well as the two stars seeking more money, James has reportedly demanded even more control of the script and rumours persist that original director Sam Taylor-Johnson has pulled out of any further involvement in the franchise.