Chieftain Capital Management, an investment firm with about $3 billion in assets, is breaking up following a rift among its managers, the Wall Street Journal reported on its website on Sunday.

Glenn Greenberg, a co-founder, plans to stay at the firm, which will be renamed Brave Warrior Advisors, the paper reported.

Co-founder John Shapiro along with two partners -- Tom Stern and Joshua Slocum -- will leave to form a new firm, effective January 1, that will keep the Chieftain Capital name, the paper reported.

Although Chieftain's partners remain committed to the firm's investment philosophy, differences on internal firm matters have led us to decide to separate, the Journal quoted a letter sent to the investors as saying.

Greenberg and Shapiro founded Chieftain in 1984, the paper said. Chieftain had made the headlines nearly two years ago when it called for the ouster of Comcast Corp Chief Executive Brian Roberts.

Last month, Greenberg weighed in on Comcast's talks over General Electric Co's NBC Universal.

People are scared, they don't trust Brian, he's seen as an empire builder, Greenberg told Reuters. The problem is that they have low credibility for overpaying for assets.

Chieftain could not immediately be reached for comment.