A top Verizon executive who has struggled trying to turn the telecom giant into an advertising rival to Google and Facebook will be replaced next month and intends to leave altogether by the end of the year.

Tim Armstrong, who was the chief executive of AOL when Verizon bought his company in 2015, was responsible for leading Oath, the Verizon subsidiary that contains AOL and Yahoo.

Armstrong will be succeeded on Oct. 1 by K. Guru Gowrappan, Oath's president and chief operating officer, Verizon said in a release Wednesday. Armstrong will take an advisory role at Verizon to guide the leadership transition before departing by year's end, the company said.

The announcement comes a year after Verizon completed its acquisition of Yahoo in an attempt to create a digital advertising giant that could take on Silicon Valley. Its aim was to use behavioral data from Internet users to sell highly targeted advertisements, particularly on video.

But the company has faced difficulty gaining traction. Earlier this year, it shut down its fledgling proprietary video app, Go90, which sought young audiences with short, shareable clips. And reports last week suggested Verizon was having trouble gathering the type of user data the company needed to create a more competitive advertising business.

“We are exceedingly grateful to Tim for his contributions in founding Oath as a force in digital media and technology,” Verizon chief executive Lowell McAdam said in a statement. “With his continued guidance over the next few months, our enthusiasm for Oath’s potential has never been greater.”