(NEW YORK) — Verizon is replacing its media and advertising chief Tim Armstrong. Oath President and COO K. Guru Gowrappan will assume the Oath CEO role Oct. 1. Armstrong will stay through year-end as a strategic adviser. Gowrappan joined Verizon in April and before that was global managing director of Chinese e-commerce behemoth Alibaba. Armstrong was tasked with growing Verizon’s ad business in a challenge to Facebook and Google, but that business remains one of Verizon’s less profitable divisions.