While 2019 might not see the mega-mergers of 2018, “I don’t think it will be a slow year,” predicts Stephen Burrill, vice chairman and health care leader at Deloitte LLP.

Much of the action is expected to come from retailers linking up with payers or providers, or from health insurers or health care systems acquiring services such as home health care providers and rehabilitation facilities. Payers and providers have begun to realize “maybe this is a better answer if we work together and think about the patient holistically,” Burrill says. With that type of vertical integration, “you help manage money,” with the goal of reducing health care costs, he adds.

During the first three quarters of 2018, nearly 800 health care deals were announced, valued at almost $115 billion, according to PricewaterhouseCoopers. By far the largest were Cigna’s $67 billion acquisition of Express Scripts and CVS Health’s $69 billion acquisition of Aetna. For 2017, the number of health care deals totaled 967, with a combined value of $175.2 billion. The Cigna–Express Scripts deal may not close until mid-2019, several months after it was expected to, and California, New York and New Jersey regulators are still reviewing it. The CVS–Aetna merger has also run into snags. It has gotten the Department of Justice’s approval but early this month Judge Richard Leon of the U.S. District Court for the District of Columbia said he might require the companies to remain separate until he can review the merger and consider anti-trust issues. “I can’t recall another instance of a judge doing this,” Andrea Agathoklis Murino, co-chairperson of Goodwin Procter LLP’s antitrust and competition law practice, told CNBC.

In a November earnings call, CVS CEO Larry Merlo said the company would work to help better manage customers’ chronic conditions, such as diabetes, through the integration of CVS’s and Aetna’s claims data, according to media reports.

CVS is planning to launch new “health hub” stores this year that will provide “new services to better address the cost-quality-access challenges of consumers,” Merlo said. The hubs would reportedly use pharmacists to help manage patients’ care between visits to primary care providers. The pilot efforts would initially involve Aetna members, but could be expanded to other health plans.

Meanwhile, Humana and Walmart have been talking about merger-slash-partnership arrangements, according to media reports, but as 2018 waned they had yet to make any kind of big-splash announcement. Humana has partnered with Walgreens to test senior-focused primary care clinics in Kansas City.

Insurers are busy merging with retailers and providers in vertical integration deals after attempts at horizontal combinations hit antitrust roadblocks. In 2017, federal judges ruled against Humana’s proposed tie up with Aetna and a Cigna–Anthem merger. And the bar for horizontal mergers got a little higher this year. California approved a law that requires that any health insurers who want to merge to first gain approval from the state’s Department of Managed Health Care. The department can reject mergers that limit competition.

Other vertical deals this year included Humana’s acquisitions of a Curo Health Services, a hospice provider, and Family Physicians Group in Orlando, a primary care provider. Meanwhile, Centene announced it was acquiring Community Medical Group, a primary care provider in Miami-Dade County. Anthem acquired Aspire Health, a palliative care provider.

Whether the enthusiasm for vertical integration will go too far and start bumping up against antitrust objections is one of the important questions going into 2019. An example might be a health insurer acquiring all the rehabilitation facilities in a particular market. “There may be a point where it’s too big,” Burrill says.