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. Armstrong came to Verizon when it bought AOL in 2015 and began overseeing Yahoo when Verizon bought it in 2017.
Armstrong was one of Google's early employees and was key to developing its digital ad business before joining AOL in 2009. Telecoms have been buying content makers to diversify as the wireless industry slows.
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