Amazon inaugurated its migration into the health care industry some time ago when it launched an online pharmacy and telemedicine service almost everywhere in the United States.

And then last year Amazon announced the expansion of Amazon Care, which dispenses “high-quality medical care and advice’ 24 hours a day, 365 days a year, with a goal of delivering the service through companies of all sizes to their employees nationwide.

Taking this initiative even further, this week Amazon and primary-care provider One Medical announced that they have entered into a definitive merger agreement under which Amazon will acquire One Medical.

One Medical says it is is a human-centered, technology-powered national primary care organization on a mission to make quality care more affordable, accessible, and enjoyable through a seamless combination of in-person, digital, and virtual care services that are convenient to where people work, shop, and live.

Amazon still makes most of its revenue from orders placed through its online stores, and most of its profit from its cloud computing arm. Both of those businesses were built almost entirely in house. But Amazon’s largest acquisitions show the company is willing to buy growth in markets that are adjacent to its core competencies.

Before One Medical, Amazon’s two largest acquisitions ever were its $13.7 billion purchase of grocery chain Whole Foods in 2017 and its $8.45 billion purchase of film and television distributor MGM Studios last year.

MGM and Whole Foods deals also tie back to the company’s Prime subscription offering, which gives it a steady stream of recurring revenue from millions of consumers and encourages loyalty. One Medical could follow that same template. Amazon has already added pharmacy benefits to Prime.

Amazon has dabbled in healthcare for several years. Amazon bought PillPack in 2018 for $750 million, then rolled out its own online pharmacy. It also launched Amazon Care, a service that has both telehealth and in-person offerings, first for its own employees before opening it up to other employers last year. The offering competes with One Medical.

Amazon will acquire One Medical for $18 per share in an all-cash transaction valued at approximately $3.9 billion, including One Medical’s net debt. Completion of the transaction is subject to customary closing conditions, including approval by One Medical’s shareholders and regulatory approval. On completion, Amir Dan Rubin will remain as CEO of One Medical.

One Medical is a U.S. national human-centered and technology-powered primary care organization with seamless digital health and inviting in-office care, convenient to where people work, shop, live, and click. One Medical’s vision is to delight millions of members with better health and better care while reducing costs, within a better team environment. One Medical’s mission is to transform health care for all through a human-centered, technology-powered model. Headquartered in San Francisco, 1Life Healthcare, Inc. is the administrative and managerial services company for the affiliated One Medical physician-owned professional corporations that deliver medical services in-office and virtually. 1Life and the One Medical entities do business under the “One Medical” brand.