Amazon is now the most publicized case study of a successful media network from a commerce firm. But other retailers like Best Buy and Walmart have also quietly built profitable ad businesses over the past few years, and they are likely to take share from digital incumbents in the years to come. By serving ads to their customers at relevant moments, digital business professionals and commerce companies deliver a superior customer experience while also cultivating a rapidly growing new revenue stream with healthy margins. This report is an update of a previously published report.