GroupM is bringing its supply path optimization efforts to over-the-top media, choosing SpotX as its preferred supply-side platform for video inventory. The partnership comes as WPP’s media buying arms adds video to its Premium Supply offering in the U.S. GroupM Premium Supply lets the agency’s clients buy programmatic inventory more transparently and with pricing benefits… https://www.adweek.com/programmatic/groupm-continues-supply-chain-optimization-efforts-with-spotx-partnership/