DEERFIELD, Ill. — Walgreens Boots Alliance Inc. (WBA) and Rite Aid Corp. have lengthened the time frame for completing their planned $17.2 billion ­merger. The companies this month extended the deal’s end date to January 27 from October 27 and said they expect the transaction to close early next year.

Under the agreement, WBA and Rite Aid both had the right to extend the time frame. WBA had announced the agreement to acquire Rite Aid for $9 per share in cash, plus debt, in October 2015.

WBA reiterated the update that it gave on the deal in early September and said the process for gaining approval from the Federal Trade Commission is “progressing as planned.”

The company remains actively engaged with the FTC “regarding its review of the pending acquisition and continues to expect that the most likely outcome will be that the parties will be required to divest between 500 and 1,000 stores,” WBA said. “The company believes that it will be able to execute agreements to divest these stores to potential buyers, pending FTC approval, by the end of calendar year 2016 and now expects its acquisition of Rite Aid will close in early calendar 2017.”

WBA said in September it appeared that more than 500 Walgreens and/or Rite Aid stores would need to be divested for regulatory clearance of the deal but that it still expected to have to shed fewer than 1,000.” The company also said at the time that it expected the deal to close in the second half of 2016.

WBA had previously indicated that it was willing to shed up to 1,000 stores to gain regulatory clearance but expected divestitures to total less than half that number. Walgreens has 8,173 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.

Media reports in recent weeks cited sources saying that WBA was struggling to find a buyer. Reports said Kroger Co. was undecided about purchasing some of the outlets because the FTC was insisting that the divested units remain stand-alone drug stores, rather than allowing Kroger to integrate their pharmacies into nearby supermarkets. Late last month, reports said a block of 650 stores earmarked for divestiture didn’t attract interest from private equity firms.

When WBA and Rite Aid announced the acquisition deal last fall, industry observers named CVS Health, Walmart and Kroger as potential buyers of divested stores. However, Walmart has scaled back its small-format store strategy, and reports have said that CVS has expressed concerns about store cannibalization.

“Even if Kroger is an uninterested buyer, potential remaining Rite Aid store buyers include CVS, regional pharmacy chains and private equity in regional areas where they can buy enough stores to give them scale,” wrote Deutsche Bank Securities analyst George Hill. “While Kroger is on the list of potential suitors, we do not view them as core to the store sales, as their business is largely focused on a different store format than the stand-alone pharmacy stores that Walgreens/Rite Aid would be selling.”