The Brit was thrilled when she was asked to audition for the Oliver Stone movie, in which she plays the daughter of Michael Douglas' infamous Gordon Gekko character.
And she insists she was never nervous about meeting Stone and reading for the role - because "the universe" had already told her she was destined to land the part.
Mulligan, 24, explains, "When I got closer to reading the script, the universe just started sending me all these signals. I was staying here (in New York) and the night before I left for Los Angeles, I rented Risky Business and I was opening the DVD and the DVD in my TV came out and it was Wall Street.
"And then I was on the plane reading my horoscope, which I never do, and it said, 'Remember, like Gordon Gekko said in Wall Street, 'Green is good'!' At which point, I was like, job's mine!"