Walmart Inc.’s Walmart Media Group advertising technology business is making a push to attract a larger share of retailers’ advertising dollars.

The retailer, No. 3 in the 2019 Digital Commerce 360 Top 1000, has rolled out a self-serve portal that enables advertisers to directly buy on-site search and sponsored product ads that appear on Walmart’s ecommerce sites and apps. It is also making that inventory available through an application programming interface to digital marketing vendors Flywheel Digital, Kenshoo, Pacvue and Teikametrics, each of which is a member of retailer’s new Walmart Advertising Partners program. Advertisers previously had to purchase search ads and sponsored product placements through an agency.

The move allows advertisers to use Walmart’s massive trove of online and offline consumer data to better target consumers and measure the impact of those ads.

“With 90% of America shopping at Walmart every year and nearly 160 million visitors to our stores and website every week, Walmart Media Group enables brands to reach more customers at scale and measure advertising effectiveness across the entire shopping journey,” writes Lex Josephs, Walmart Media Group’s vice president sales and media partnerships. “Now, brands can tap into Walmart’s shopper footprint to get the the right sponsored ad experience, to the right shopper at the right moment.”

The move comes less than a year after Walmart bought the advertising startup Polymorph’s technology and assets, which included a high-speed ad server, a self-serve interface and server-side header bidding. At the time of the deal, Walmart argued that the technology would enable the retailer to make it easier for advertisers to learn the system, select audience segments based on shopping behaviors, automate ad delivery and then measure whether their ads influenced a sale.

“This is a smart move by Walmart, and it’s a model we’re continuing to see marketplaces follow,” says Chris Dessi, vice president at Productsup, a product experience management company. “As more options for self-serve advertising unfold, large enterprise dollars will become more distributed across marketplaces.”

The timing of the rollout is “perfect,” he says, because it gives Walmart time to build out its advertising arsenal throughout this year as it looks to take on the fast-growing Amazon Advertising business, which generated $9.80 billion in U.S. revenue last year, according to research firm eMarketer Inc.