According to The Wrap, sources confirm that Paul Rudd is in negotiations for the role; however, reps for Rudd and Marvel haven't officially commented.
It's noted that Rudd has appeared slimmer in recent interviews, which is said to be due to his physical training for Ant-Man.
Joseph Gordon-Levitt was said to be a contender for Ant-Man, but is no longer with his involvement in Warner Bros. and DC's Sandman movie.
Ant-Man has a July 31, 2015 release directed by Edgar Wright with a script by Wright and Joe Cornish.
Head on over to the Cosmic Book News Avengers movie hub for more.