In a way, the news out of MGM on Wednesday was merely a formality 15 years in the making — an open acknowledgement that Gary Barber is the moneyman and Roger Birnbaum is the moviemaker.

The longtime partners were co-chairman since taking over the Lion nearly two years ago, but Birnbaum will shed that title to produce fulltime, leaving Barber as the sole chairman and CEO. Birnbaum will remain in his current executive suite in Beverly Hills and will produce and develop new projects exclusively for MGM. His first task: Serve as exec producer and oversee production of the “RoboCop” reboot, which started principal photography Sept. 15.

Barber has generally focused on the financials while Birnbaum specialized in talent relations. Birnbaum may, however, have a little more freedom to get hands-on with MGM’s library-mining operation, focusing on upcoming redos including “Poltergeist,” with Sam Raimi producing; “Death Wish,” with Joe Carnahan directing; “WarGames,” with Seth Gordon directing; as well as “The Magnificent Seven,” “Carrie” and “Valley Girl.”

“Gary and I decided two years ago to accept the challenge of joining MGM and restoring the company to its rightful place in the industry. I am very proud of where MGM is today,” Birnbaum said. “I have been in the film business a long time, and my greatest passion has always been producing. Now is the time for me to return to what I love to do the most … producing films. And the fact that I will be producing for MGM, with Gary, my partner and friend, will be very gratifying.”

Barber and Birnbaum have been in partnership since the late 1990s, when they formed Spyglass Entertainment as a financing-producing banner. Spyglass saw its greatest successes with “The Sixth Sense” and “Bruce Almighty”; the duo own the Spyglass library.

“I respect Roger’s decision to return to his passion of ‘hands-on’ producing, and we are thrilled he has chosen to stay at MGM on an exclusive basis,” Barber said. “We have shared many successes together, and I look forward to many more. I have the utmost confidence in Roger’s ability to produce many of our key upcoming productions, and I could not be happier that we will continue to work together.”

MGM Holdings’ board of directors head Ann Mather said in a statement, “We want to thank Roger and look forward to him producing upcoming MGM films and have full confidence in Gary continuing to lead the company with the talented management team in place.”

Barber and Birnbaum were appointed co-chairmen and CEOs of MGM in December 2010 as the company emerged from a pre-packaged bankruptcy. Since that time, they have secured a distribution and co-financing partnership with Sony Pictures Entertainment, which includes “Carrie,” “The Girl With the Dragon Tattoo,” “21 Jump Street” and the 23rd James Bond pic, “Skyfall.”

Warner Bros. is partnered with MGM on the three upcoming “Hobbit” films, with WB assuming MGM’s share of producing costs in exchange for taking over the international distribution and homevid on the films from MGM. The Lion is partnered with Paramount on “G.I. Joe: Retaliation” and “Hansel and Gretel: Witch Hunters.”

In addition, Barber and Birnbaum renewed MGM’s home entertainment distribution pact with Fox last year, extending the agreement through 2016. MGM TV shows created during the Barber-Birnbaum tenure include “Vikings” and “Teen Wolf”; MGM is also in development on the upcoming “reimagined” unscripted series “Fame” in partnership with Nigel Lythgoe.

MGM put itself up for sale in August 2009. Its pre-packaged bankruptcy wiped out more than $4 billion in debt and led to a $500 million cash infusion arranged through JPMorgan.

A public stock offering is under consideration at the company, which announced in August that it had posted second-quarter earnings of $42.1 million, or nearly four times the $12.2 million in earnings in the 2011 quarter.

MGM had disclosed in July in a filing with the Securities and Exchange Commission that it was considering an IPO under new legislation that allows companies with under $1 billion in revenue to keep the process confidential until 21 days before a roadshow.