How do you make a movie from a book about bad banks?

“That’s what excited me about it. I read the book in one night,” director Adam McKay told Deadline’s Dominic Patten today on why he chose to make a feature adaptation of Michael Lewis’ book The Big Short: Inside the Doomsday Machine about the guys who made a killing during the 2007-2008 financial crisis.

For a director who built his career on tentpole Will Ferrell comedies like Anchorman and The Other Guys, the chance to segue to a drama laden in financial-speak “was freer than I ever felt,” said McKay. “It was freeing to get away from a hard genre.”

the big shortWhat piqued McKay about Lewis’ tome was how the author broke through the fourth wall in his text, and the potential opportunity to do that on the bigscreen. In his book, to explain the complicated financial processes to the reader, Lewis provides footnotes. In the clip shown today where Ryan Gosling’s character Jared Vennett pitches Steve Carell’s Mark Baum on committing to a credit default swap, financial definitions appeared on the screen, an ongoing visual motif that McKay maintains throughout the film.

“It was nice that there wasn’t pressure to have to deliver the great big laugh in a scene,” said McKay. Where the director’s comedy chops came into play in The Big Short, particularly with his Ocean’s Eleven-like cast that also includes Brad Pitt and Christian Bale, was McKay’s hand in improv, a skill he nurtured years ago under late Chicago comedy guru Del Close.

“We knew we had to have something interesting happen since the film was character driven and what I took from my comedies was letting these actors go loose on the script,” explained McKay. Key vamp scenes include those with Carell, Hamish Linklater and Jeremy Strong, whose finance guys are based on a group who are “constantly breaking each other’s balls,” adds the director. In the editing room, McKay crafted a blend of improv and written dialogue. Pitt was a gamer with improv, and Bale “loved being pushed.”

Paramount is premiering The Big Short at the AFI Film Festival on Thursday. The film opens in limited release on December 11 before going wide on December 23.