I always wondered this. I've seen the movie only twice or so since its release, but I don't remember anything in the movie that required such a high budget. Not even American Sniper had a big budget like this.
shareThe budget swelled because Matt Damon, Paul Greengrass, and the studio were unhappy with the original tame ending. The last third of the movie had to be reshot, which was complicated by the fact that Damon had already left to shoot The Informant! (2009) and the shoots had to be restaged months later to accommodate his schedule.