That's according to director Peyton Reed, who tweeted the following earlier today:
Ladies and gentlemen, that is an ANT-MAN picture wrap for Mr. Paul Rudd!— Peyton Reed (@MrPeytonReed) December 5, 2014
Rudd stars in the film with Michael Douglas, Corey Stoll and Evangeline Lilly. He'll play Scott Lang, who will become Ant-Man after the technology developed by Hank Pym (Douglas) falls into evil hands, presumably following a corporate takeover by Darren Cross (Stoll).
Ant-Man will be in theaters on July 17, 2015.