Fox Networks Group said Monday that company veteran Toby Byrne is stepping down as president of ad sales to explore other opportunities.
The move appeared not to have been expected; Fox said it will begin its search for a successor immediately.
The company declined to elaborate on the departure of Mr. Byrne, who has held the post since October 2014, and previously led ad sales for the Fox broadcast network since January 2011.
His role atop Fox's broadcast and cable portfolio was created for Mr. Byrne, combining sales responsibilities that had been handled separately.
"Toby is an extremely talented and admired member of our leadership team and has left an indelible mark over his long career at Fox," Fox News Group President-Chief Operating Officer Randy Freer said in a statement. "Our exceptional results in this year's upfront attest to Toby's expertise, business abilities and personal integrity. "
Mr. Byrne said he was grateful for his time at Fox. "I'm leaving the company at a time when we are extraordinarily well positioned to achieve and exceed our goals after an exceptional upfront season," he said in the company's statement.
Mr. Byrne's tenure benefited from the white-hot debut of "Empire" on Fox in January 2015. The show expanded its audience each week in its first season, an unprecedented feat in modern TV.
Its second season included a three-episode integration for Pepsi, which was written into the plot as a character competed to become the brand's new endorser. The fictional character then makes a real Pepsi commercial (directed in real life by "Empire" co-creator Lee Daniels) that debuted, of course, during an "Empire" commercial break.
The idea started as a storyline in the series, not a product placement pitch, Mr. Byrne told Ad Age last year. Pepsi was then approached for the deal.
Until Fox Networks Group identifies a successor, ad revenue will be overseen by Mr. Freer and Mr. Byrne's day-to-day responsibilites will be assumed by Bruce Lefkowitz, exec VP-advertising sales; Danielle Maged, exec VP-global partnerships; and Joe Marchese, president of advanced advertising products. Mr. Lefkowitz and Ms. Maged will now report to Mr. Freer; Mr. Marchese will continue to report to him.