With a proposed $17.3 billion deal to buy WellCare Health Plans Inc., Centene Corp. is set to become the third-largest publicly traded managed care provider, based on membership data compiled by S&P Global Market Intelligence.

"Centene has been more acquisitive and slowly edged itself toward the top five," said David Windley, a Jefferies analyst. "This deal kind of makes it so you can't think of them as one of the small guys anymore." The merger might help Centene "leapfrog" over Humana Inc. from a revenue perspective as well, he added.

WellCare stands to be a good asset to Centene, said Cantor Fitzgerald analyst Steve Halper. Centene CEO Michael Neidorff in an earlier conference call said the transaction provides "compelling" synergies for the two like-minded companies.

"From Centene's perspective, it adds a lot of scale," Halper said. "It brings along Medicare capabilities and an excellent management team."

Both Centene and WellCare focus heavily on Medicare and Medicaid business. If the merger goes through, the combined entity would be the top Medicaid provider in the country and boast a membership of 12.3 million individuals, according to a company presentation.

Centene said it expects the merger to close in the first half of 2020.

Cantor's Halper does expect the deal to face regulatory scrutiny. But he believes it will be easier for the companies to sell assets that will allow it to go through compared to the failed Aetna Inc.-Humana and Anthem Inc.-Cigna Corp. mergers several years ago.

"[Centene] has made some unspecified assumptions about what sort of divestitures the government would ask in particular markets," Halper said. "I think it's reasonable to expect some divestitures ... but it will take at least a year."

Jefferies' Windley noted that the companies share some material overlap in Florida, Georgia, Illinois and Missouri. Another analyst on the conference call discussing the deal pointed out that there are several states where Centene already controls a significant share of the Medicaid market, raising a possible antitrust concern. Executives sought to play down those concerns, saying the geographical issues are "manageable" and indicating that the companies would start to have conversations with the states immediately to successfully navigate any troubles.

In the end, Halper expects a smooth integration, largely because of how well Centene was able to integrate some smaller companies in recent years.