GroupM is making a major play for commerce revenues as retail media continues to rise. Ex-Amazon and IPG Mediabrands' Cadreon boss, Marc Lomas, is spearheading the play – along with former Goodman Fielder marketer Leah Jackson, who in her previous gig played a key role in handing trade marketing budgets as well as media to Initiative. Now at GroupM Commerce, the duo will be aiming to convince more brands to take a similar approach. But that requires proving incrementality – i.e. that media investments are leading to new sales and hard growth outcomes and linking measurement across all digital channels directly to the in-store shop floor. No mean feat, but Lomas, Jackson and Mindshare CEO Maria Grivas say they can do it. First port of call? Busting measurement mind-sets away from “dumb” ROAS metrics, per Lomas. Then convincing more brands that an integrated operating model that aligns sales, marketing, brand, ecom and retail media should no longer be an outlier.