The leaders of CVS Health Corp. plan to split the business into two companies centered around the Aetna insurance business and the 9,000-store retail pharmacy chain. The move will essentially undo the acquisition of Aetna by CVS eight years ago, a $78 billion deal that promised to unite insurance, pharmacy benefit management and Main Street care delivery.

Chairman and CEO David Joyner and his team plan to complete the separation by mid-2028, when each division will become separate public companies. The CVS Pharmacy group will keep that name as a standalone business and also house the company’s mail pharmacy and MinuteClinic divisions as well as its Health100 technology platform. The remaining business clustered around Aetna include the CVS Caremark PBM and its specialty pharmacy group as well as care providers Oak Street Health and Signify Health, which run Medicare clinics and in-home and preventative care services. That company will be named CVS Health for now but looks to be in line for a rebrand.

Speaking on a Nov. 4 conference call with investors and analysts, Joyner said there have been some benefits to having certain businesses under the same roof but that retail pharmacy hasn’t connected tightly enough to the rest of the business to continue as is.

“What we’ve done in the last two years is integrate quite a bit inside of CVS Health with both Caremark and Aetna and some of the health care delivery assets. That’s helping us lean into value-based care,” Joyner added. “But retail has, for the most part, for the last two decades [since CVS bought Caremark], operated behind the firewall. We’ve always had to negotiate at arm’s length.”

Later in the conversation, Joyner said CVS Pharmacy—which will be led by Prem Shah and will have about $145 billion in annual revenue compared to the future CVS Health’s $320 billion—will still be tied to the Aetna/Caremark business because of the “unique products” that have been built since 2006. Those, he said, will be governed by deals that’ll get hammered out in the next 18 months.

“We don’t need the integration of an operating structure,” Joyner said. “We need to make sure that we’re aligned around where we believe that there can be value creation and make sure that there’s an appropriate commercial agreement in place to support that.”

Separating the two businesses also will make life simpler from a policy and regulatory perspective—even though the word “regulatory” came up just once, during Joyner’s introductory remarks, during the hour-long conference call. But Arielle Trzcinski, principal analyst at Forrester, said the leaders of CVS and their peers at other healthcare powerhouses should expect “even greater scrutiny in 2027” of their business models grouping insurers, pharmacies and PBMs with care delivery organizations.

“CVS Health is effectively acknowledging that bigger isn’t always better. Increasingly, large brands are pursuing partnerships, ecosystem curation, and orchestration to create value without the cost and complexity of owning every piece of the consumer journey,” Trzcinski said. “Rising regulation has changed the strategic calculus for these megabrands.”

Investors weren’t at all thrilled with the idea of splitting up today’s CVS. On a post-election day when the broader market rose about 1.7 percent, shares of CVS (Ticker: CVS) fell more than 10 percent on the open and never recovered. They finished trading down 12.5 percent at $79.96, their lowest level since late April. The company’s market capitalization is now about $104 billion.