DEERFIELD, Ill. — Walgreens Boots Alliance Inc. (WBA) has upped the number of stores that it expects to divest to gain government clearance for its $17.2 billion purchase of Rite Aid Corp.

WBA said this month that between 500 and 1,000 Walgreens and/or Rite Aid stores will probably have to be divested to win Federal Trade Commission approval for the deal.

The company had previously said it was willing to shed up to 1,000 stores to get the agency’s OK but that it expected the required divestitures to be less than half that number. Together, Walgreens and Rite Aid would create the largest U.S. chain drug retailer, with more than 12,700 stores. CVS Pharmacy has around 9,600.

WBA said that it and Rite Aid “remain actively engaged” in talks with the FTC regarding the acquisition, which was announced last October. “As a result of the progress of these discussions with the FTC staff, Walgreens Boots Alliance is exploring potential divestiture remedies to address certain issues,” the company said.

WBA added that it continues to believe that the acquisition will close by year-end. In reporting third quarter results over the summer, the company said the acquisition was “progressing as planned” and that it was “continuing its integration planning.”

In the more recent statement, WBA said it expects the Rite Aid acquisition to be accretive to adjusted earnings per share in the first full year after the deal is finalized. It added that it continues to expect acquisition synergies of over $1 billion to be fully realized within three to four years. “These synergies have been updated where practicable and, as previously disclosed, are expected to be derived primarily from procurement, cost savings and other operational matters,” the company said.

The update on the merger came on the heels of media reports naming Kroger Co. as a possible buyer of divested stores. CVS Health has also been mentioned as a prospective purchaser. Analysts have said that government approval of the merger may hinge on one or more big, financially stable companies being ready to buy stores.

Walgreens, which already has outlets in all 50 states and Washington, D.C., has said that the addition of Rite Aid will fill gaps in its operating area in the Northeast and Southern California. Walgreens has 8,150 stores, including outlets in Puerto Rico and the U.S. Virgin Islands, while Rite Aid operates 4,560 stores in 31 states and the District of Columbia. The Northeast and Mid-Atlantic regions appear to be where Rite Aid will bring the biggest benefit in coverage.

Wolfe Research analyst Scott Mushkin recently said the store concentration being created in a number of markets loomed as a regulatory hurdle. “While we have long believed that the transaction seems to go directly against the FTC/DOJ [Department of Justice] guidelines, one possibility could be that the FTC requires more store divestitures than are being contemplated by the merger agreement,” he wrote. Increased divestitures “may be the path of least resistance,” he said.