AppNexus co-founder Brian O’Kelley is stepping down from his role as CEO following its purchase by AT&T as the telco moves to integrate the ad-tech company into its recently rebranded media and advertising unit Xandr. O’Kelley will move to an advisory role within Xandr, according to reports citing sources familiar with the reorganization. This will… https://www.adweek.com/programmatic/appnexus-co-founder-steps-down-as-ceo-following-att-acquisition/