Walmart Media Group (WMG), the retailer’s data-driven advertising business, took another step forward with its in-house advertising program on Thursday with the acquisition of Polymorph Labs, a San Francisco-based ad tech startup. Walmart did not disclose terms of the deal or how many employees it will add with Polymorph. Polymorph, formerly AdsNative, raised a total of $10.6 million, most recently an $8.5 million round in 2015 led by the Japanese retail and ecommerce giant Rakuten. The deal gives Walmart the supply-side ad stack it needs to deliver full campaigns and reports to brands, including an ad server, a server-side header bidding tool and a self-serve buying interface. WMG didn’t have a commercial deal with Polymorph, but over the past few months has evaluated vendors in supply-side ad serving and analytics and liked Polymorph’s tech and its focus on native advertising, said WMG VP and general manager Stefanie Jay. Adding Polymorph will strengthen WMG’s attribution reporting by connecting ad server data directly to the retailer audience ID and transaction data. It also creates a self-serve buying platform, which most brand marketers are accustomed to for online buys. “We are definitely moving this advertising business in-house,” Jay said. “We feel we need to own that end to end.”

Earlier this year, WMG expanded its buy-side operations by in-housing the media planning capabilities and agency services previously managed by Triad, the retail agency owned by GroupM’s Xaxis.

WMG still has a few key ad tech partners in place. Experian Marketing Services provides the onboarding and matching from a brand’s CRM to Walmart’s first-party database, Jay said. And AppNexus is the partner for programmatic audience extension.

Most of WMG’s inventory comes from its owned-and-operated properties – Walmart’s sites and apps and those of ecommerce marketplaces it’s acquired. But it also buys on social media channels like Facebook, Instagram and Pinterest, with AppNexus covering the open web.

Polymorph’s tech is also critical for WMG’s ad platform road map, Jay said. For instance, the company supports cost per click and cost per impression metrics, as well as cost per conversion for some ecommerce campaigns, or when people order grocery pickups. With the ad server and header bidding tech, WMG can evaluate real-time bids from each of its buying models.

WMG’s ad tech advancements are part of a much larger commitment from Walmart to own its customer experience and foster direct engagements between brands and shoppers, Jay said. “We’re evolving as a retailer and advertising is an important part of that.”