Is it a comedy? Is it a drama? To look at, The Big Short might seem the former. It stars funnyman Steve Carell. It’s directed by Adam McKay, the filmmaker behind lightweight fare like the Carell-starring Anchorman and Talladega Nights. And the recent Golden Globe awards placed it in the ‘Best Film – Musical or Comedy’ category (though don’t read too much into that; that category’s eventual winner was Ridley Scott’s sci-fi The Martian).

Given that The Big Short deals with the US housing market bubble that burst in 2007, precipitating the global recession, it’s hardly a subject ripe for humour. “I never thought of it as a comedy,” admits Carell, dressed in a smart charcoal suit when we meet in a hotel in London’s Soho. “Again, it’s in the eye of the beholder. Some people might walk away it’s purely a comedy. When I saw it for the first time with an audience, I was a bit taken aback by how many laughs there were in the movie.”

Adapted from Michael Lewis’s bestseller, the film has characters speaking to camera while off-the-wall asides are utilised, as various celebrities playing themselves – not least actress Margot Robbie in a bubble bath – pop up to explain financial jargon. “It is complicated material and I think Adam had a great way of putting some sugar with the medicine,” argues Carell, 53. “Nobody wants to go see a movie about Collateralised Debt Obligations! It just doesn’t sound like a sexy movie to go to.”

In the film, Carell plays Mark Baum, a hedge-fund manager who becomes one of several characters to spot the impending financial crisis before it caused chaos on Wall Street. Others include Christian Bale’s near-autistic number-cruncher, Brad Pitt’s former banker and Ryan Gosling’s alpha-male financier – all of whom ultimately bet on the collapse for huge profits. Spotting what will ultimately cause misery to millions hardly makes them heroes, of course.

If all this sounds like The Big Short is a typical exercise in Hollywood bad taste, the film’s early levity gives way to anger. One scene sees Pitt’s New Age-y Ben Rickert scold his two younger companions, as they gleefully celebrate their potential windfall, before delivering a long speech about how many people will loses their jobs, homes and even lives because of the financial crash. “That to me is the crystallising moment of the movie,” says Carell, whose own character is based on real-life manager Steve Eisman.

As the film unfolds, Carell, Pitt and the others do emerge as the good guys; or, at least, the guys who tried to warn the others that the bubble was about the burst. “All of the guys in this world, you talk to them now and you can sense that they’re still angry about it and they’re baffled by it, heartbroken in a way,” says Carell. “They tried to alert people. They went to newspapers. They were to the ratings agencies, to almost universally deaf ears. Nothing changed before it happened and certainly nothing has changed since.”

Curiously, next month, Carell can be seen playing flamboyant gay rights activist Steven Goldstein in Freeheld, the real-life story of a lesbian couple (played by Julianne Moore and Ellen Page) caught in a legal struggle. In some ways, both Goldstein and Baum are crusaders. “If there is a common thread, it’s the sense of injustice that these guys feel, and trying to set things right,” acknowledges Carell. “But at the same time, they both have an ulterior motive. In Freeheld, this guy wants to get gay marriage to the forefront of the public consciousness. In The Big Short, my character stands to make a fortune.”

For Carell, it marks yet another step towards dramatic roles after a two-decade career in comedy that saw him win a Golden Globe for playing the excruciating team manager Michael Scott in the US version of Ricky Gervais’ acclaimed sitcom The Office. A transition that usually trips up most comics, Carell proved his mettle in the dramatic arena a year ago, winning his first Oscar nomination for playing the eccentric, unhinged multi-millionaire John E. du Pont in Bennett Miller’s Foxcatcher.

Is he surprised at this recent switch? “I try not to question it too much,” he shrugs. “With Foxcatcher – I was stunned that Bennett Miller called me about playing DuPont. I wouldn’t seem to be high on that list of actors that would be playing a part like that.” He was equally befuddled when McKay asked him to play Mark Baum. “When he talked about the other people who were going to potentially sign on to do it, I thought, ‘Wow – I’ll be in a movie with Christian Bale! How does that work?’”

Born in Massachusetts, the son of an electrical engineer and psychiatric nurse, Carell gravitated towards comedy early – learning his craft in improv workshops at Chicago’s Second City, where he met Nancy, his future wife and mother of their two children. Early gigs included performing sketches on The Dana Carvey Show, Saturday Night Live and nightly satire The Daily Show, before film roles in Bruce Almighty and Anchorman, opposite Jim Carrey and Will Ferrell respectively, put him on the Hollywood map.

Yet unlike his aforementioned co-stars, who have often struggled in their rare dramatic outings, Carell is gradually being accepted as an all-rounder. “It’s strange to talk about,” he admits. “I don’t give much credence to how other people perceive me, because you can’t control it. If people think of me as a straight ahead comedy guy, that’s fine. If all they know me for is The Office or [the 2005 Judd Apatow-directed] The 40 Year-Old-Virgin, great. Just the fact I’ve had a career is good enough for me.”

In most Hollywood actors, you might consider this false modesty but Carell is quietly understated (with possibly the exception of his unwisely over-the-top performance in Freeheld). He’s just shot a small role in Woody Allen’s next movie, alongside Kristen Stewart and Blake Lively – twelve years on from their last collaboration Melinda and Melinda. “I get offered these things and just try to do my best at them,” he says. “And hope I don’t stick out as the weak link!”

The Big Short opens today. Freeheld is released on February 19.