Steve Mosko, the chairman of Sony Pictures Television, is leaving the company after 24 years, Variety has learned.

Mosko had been in negotiations to extend his contract, which expires this year, but failed to come terms with the studio, according to three sources.

The 60-year-old executive had just been promoted from president to chairman just last September.

Sony officials were not immediately available for comment. The shakeup is a surprise given that the TV division is the most successful entity within Sony Pictures at present. But there were rumblings within the studio of strains between Mosko and Sony Entertainment chief Michael Lynton and that Mosko was pushing for a bigger role at the studio beyond TV.

Sony Pictures is still recovering from years of struggles on the film side and the damaging effects of the unprecedented hack of its computer network and internal databases in November 2014. The fallout from that cyber attack spurred the exit of former Sony Pictures co-chairman Amy Pascal in February 2015.

Mosko has led Sony’s worldwide TV operations since 2009, when he took over the studio’s international TV operations. He started his Sony career in syndication sales, joining what was then Columbia TriStar TV in 1992.

Potential successors could come from inside Sony, where Zack Van Amburg and Jamie Erlicht have long served under Mosko as presidents of programming and production at SPT.

But it’s not clear if Sony will tap a direct successor to Mosko or possibly have his top lieutenants — including Van Amburg, Erlicht, U.S. distribution president John Weiser, international distribution president Keith Le Goy and worldwide networks chief Andy Kaplan — report into Sony Entertainment CEO Michael Lynton.

Mosko is credited with rebuilding Sony’s primetime production division with such major hits such as NBC’s “The Blacklist,” not to mention aggressively expanding into cable and streaming services, from AMC’s “Breaking Bad” to Showtime’s “Masters of Sex” to Netflix’s “Bloodline” and the upcoming Baz Luhrmann drama “The Get Down.”

Mosko was tapped to oversee all domestic TV in 2002 after Sony took the highly unusual step of shutting down its primetime operation and throwing out most of the previous executive regime. That scorched-earth atmosphere presented a leadership challenge to Mosko as Sony slowly but surely returned to the scripted TV business but in a leaner fashion than in the past. And more recently, Mosko was credited as galvanizing the TV team to overcome the operational hurdles presented by the hack.

On the international front, Mosko helped drive the studio’s overseas expansion with Sony- and AXN-branded channels in more than 180 countries. Mosko has also overseen Crackle, the studio’s streaming video service, and the GSN cable network.

The surprise shakeup comes just two weeks after the studio scored big wins with five broadcast TV series orders — a strong showing in a year when networks are particularly focused on in-house development. Sony TV landed a spinoff of “Blacklist,” as well as another drama for the network, “Timeless.” Two more series at ABC, “Imaginary Mary” and “Notorious,” as well as one for CBS, “Kevin Can Wait,” were ordered. “Timeless,” “Kevin Can Wait” and “Notorious” all landed prime timeslots.

The new series join a roster of returning Sony broadcast series including “Shark Tank,” “The Goldbergs,” “Dr. Ken” and “The Night Shift.”