With Discovery merger pending, Warner Bros. chief Ann Sarnoff is set to leave.

LOS ANGELES — Ann Sarnoff, the chief executive of the WarnerMedia Studios and Networks Group, will leave the company, with an announcement coming as soon as this week, three people briefed on the matter said.

Ms. Sarnoff, who declined to comment, was chosen to lead Warner Bros. in 2019 despite limited Hollywood experience, becoming the first woman to hold the role. She is departing as WarnerMedia, a division of AT&T, is set to complete a merger with Discovery. Ms. Sarnoff’s boss, Jason Kilar, who has been chief executive of WarnerMedia since 2020, announced his exit on Tuesday.

Like Mr. Kilar, Ms. Sarnoff found herself without a seat in the game of musical chairs that accompanies the merging of competing companies, said the people briefed on the matter, who spoke on the condition of anonymity to discuss confidential information. The Warner Bros. Discovery management structure is still unknown, but David Zaslav, the chief executive of Discovery, who will run the new company, is expected to take over at least some of Ms. Sarnoff’s portfolio. She has had a dozen direct reports.

Her job has involved oversight of HBO and HBO Max; the Warner Bros. movie and television studio; several cable channels, including TBS and TNT; and a large consumer products division. Breaking down the siloed nature of some of those units has been one of Ms. Sarnoff’s accomplishments.

Ms. Sarnoff’s job security has been the subject of Hollywood gossip for months, with agents and Warner-affiliated producers insisting that she was on her way out and some members of her team insisting the opposite. That kind of speculation can be deadly in show business, with whispers congealing into conventional wisdom, often resulting in an irrecoverable position of weakness in the view of Hollywood’s creative community.

To be fair, Ms. Sarnoff, whip smart and affable, never got the opportunity to really do her job. The pandemic shut down the entertainment business roughly seven months after she started. AT&T, which hired her, decided to spin off WarnerMedia last May.

Before joining WarnerMedia, Ms. Sarnoff held leadership roles at Nickelodeon, the Women’s National Basketball Association, Dow Jones and BBC America.