McCarthy is toplining the movie, which will begin shoot in March with Kathy Bates and Peter Dinklage also in the cast. McCarthy's husband, Ben Falcone, is in the director's chair, The Hollywood Reporter said.
The script, written by McCarthy and Falcone alongside their 'Groundlings' collaborator Steve Mallory, centers on a titan of industry who is sent to prison after she's caught for insider trading.
Bell will play the former assistant, a mousy single mother who is trying to start a cupcake business.
Bates is already onboard to play McCarthy's tough, wealthy and eccentric mentor whom McCarthy's character wants so badly to emulate.
She was also was recently seen reprising the titular role in Warner Bros' film 'Veronica Mars'.