The head of Walt Disney Studio, Rich Ross, has resigned as chairman of the film-making company, just a month after the film John Carter became one of the company’s biggest flops.

Mr Ross, who is openly gay, and has been in the company for 15 years, announced his resignation by e-mail, saying: “I no longer believe that the chairman role is the right professional fit for me.” He became the company’s chairman in 2009.

He was previously the head of the Disney Channel, and oversaw the production of High School Musical and Hannah Montana, both of which became cash-cows for the television arm of the conglomerate.

Although Mr Ross approved the production of John Carter, which cost the company about $200m in losses, the film had been in development before he was appointed to his post. News organisations report that a new chairman will not be appointed immediately.

Bob Iger, Disney’s Chief Executive, said of Mr Ross: “For more than a decade, Rich Ross’ creative instincts, business acumen and personal integrity have driven results in key businesses for Disney… I appreciate his countless contributions throughout his entire career at Disney and expect he will have tremendous success in whatever he chooses to do next.”

Mr Ross was the first openly gay head of a major film studio.