The other shoe has finally dropped at Universal Music Group. After Island Def Jam Music Group (IDJMG) chairman/CEO Antonio "L.A." Reid announced earlier this week that he's leaving his post to become a judge on Fox's forthcoming U.S. version of "The X Factor," it was also learned that former RCA/Jive Label Group chairman/CEO Barry Weiss was announced internally as chairman/CEO of IDJ and Universal Motown Republic Group.

In an internal memo obtained by Billboard, Universal Music Group chairman/CEO Lucian Grainge states, "Throughout his career, Barry achieved that rare and delicate balance between managing artistic needs and the realities of the business. He is an entrepreneur who possesses a deep love of music. He has the talent and commitment to help take these two great companies to new heights."

With the exception of the exiting Reid, a source says UMG's executive tier, including Universal Motown president Sylvia Rhone and Universal Republic president/CEO Monte Lipman and co-president/COO Avery Lipman, remains the same.

Reid's days at the label had been rumored to be drawing to an end since UMG began a leadership transition last year that culminated in Grainge's ascension to chairman/CEO, succeeding Doug Morris, who recently agreed to take the helm of Sony Music Entertainment.

While a proven hitmaker and market-share builder, Reid has long had a reputation of spending too freely on talent and marketing, to the detriment of the bottom line. Still, his track record of chart success as both a label head and a producer has garnered him the loyalty of top stars like Mariah Carey, Bon Jovi, Kanye West, Justin Bieber and Rihanna.

His cachet among artists and his stature in the urban music community prompted Grainge to try to keep him in the UMG fold by offering a joint-venture company that would be part boutique label/production deal, part artist branding/sponsorship and artist management company, according to sources familiar with the situation.

But the pending loss of his status as a major-label president and the lure of TV ultimately led Reid to resign his post and walk away from a payout for the remaining eight months on his contract, sources say.

Ironically, Reid leaves IDJ just as the label's market share is peaking once again. In 2010, the label group's share of U.S. sales of albums and track-equivalent albums (where 10 digital tracks equal an album) totaled 5.2%, up from 4% in 2009 and its best showing since garnering 5.4% in 2006, the first year that Nielsen SoundScan used that sales metric.

Reid's decision to resign instead of negotiating a package for his departure, which would have likely tied his hands until his contract ended, has fueled speculation that he may reunite with Morris at Sony Music as head of Epic Records, RCA/Jive or one of those latter imprints. Adding to this storyline is the fact that "The X Factor" is produced by Simon Cowell's Syco, a partner of Sony Music.

Other sources point out that the same lack of attention to profits that led to his departure from IDJ also contributed to his 2004 ouster as head of Arista. But an industry executive familiar with Reid and Morris says it's too early to dismiss the possibility that Reid may turn up at Sony.

"There is a new sheriff," the executive says. "Doug may be looking for market share and hitmakers, and L.A. is both. Doug may let him run the creative side and give him a co-head to make sure he doesn't overspend."

Morris isn't scheduled to assume the reins at Sony Music until July 1. In the meantime, Reid will be occupied with fulfilling his new duties as a judge on "The X Factor." The show, which is expected to debut on Fox in September, will begin holding auditions March 27 in Los Angeles.

As is the case with Fox's "American Idol," judges attend all auditions. "X Factor" judges also play a mentoring role on the show, helping contestants develop as performers. Fox has yet to say how long the season will last but the original U.K. version has aired during a five-month block from August to December.

The winner will receive a $5 million contract with Sony Music. To date, Sony Music Label Group chairman Rob Stringer has been actively involved in the "X Factor" project as well as the other music-producing cash cow on TV, "Glee."