Walgreen Co. plans to tie a bow around the acquisition of European counterpart Alliance Boots by announcing the results of a shareholder vote at a meeting Monday in New York.

Walgreen bought a 45 percent stake in the Swiss company in 2012 for $6.7 billion. Shareholders are expected to approve buying the remaining 55 percent, analysts and investors say, making way for Walgreen to close the deal by Dec. 31.

Last year, Chesterbrook drug wholesaler AmerisourceBergen Corp., which has about 850 employees in the Philadelphia area, signed a 10-year deal to supply drugs to Alliance Boots and Walgreen.

Walgreen, of Deerfield, Ill., operates the largest drugstore chain in the United States, with net sales of $76.4 billion in its most recent fiscal year ended Aug. 31. It reported 8,309 locations in 50 states, the District of Columbia, Puerto Rico, and the U.S. Virgin Islands.

About 60 Walgreens retail stores are in the eight-county Philadelphia area.

As of Aug. 31, Alliance Boots had pharmacy-led health and beauty retail businesses in 11 countries and operated more than 4,600 health and beauty retail stores.

Dec. 31 also will mark the departure of Walgreen chief executive officer Greg Wasson, who is handing the baton to Stefano Pessina, executive chairman of Alliance Boots. Pessina will lead the company until the board finds a successor and will own 16 percent of the new holding company, Walgreens Boots Alliance.

Several other Walgreen executives have left in recent months, including former chief financial officer Wade Miquelon, who sued the company in October, saying he was defamed by comments that suggested he was responsible for a $1 billion forecasting error. Kermit Crawford, Walgreen's president of pharmacy, health, and wellness, said he also would retire at the end of the year, after 31 years with the company.

Former Kraft CFO Tim McLevish replaced Miquelon, and two other Alliance Boots executives have taken posts at Walgreen.

"Alliance Boots executives are taking over Walgreens," said Michael Pryce-Jones of the CtW Investment Group, which owns 2.5 million shares of Walgreen stock, or about 0.3 percent, "and that's a very bizarre situation when you usually pay a control premium to keep control of your company."

Pryce-Jones said he thought Walgreen was paying too much to acquire the privately held Alliance Boots. His group had recommended shareholders reject the deal.

"If the market saw . . . [the] premium," he said, "I think alarm bells would be ringing."

He said he also was concerned about the company's embarking on an international expansion without clear leadership. Wasson's departure was unusual, if not surprising. On Nov. 24, a proxy the company filed with the Securities and Exchange Commission said Walgreen fully expected Wasson to continue as CEO of Walgreens Boots Alliance.

Other major investors, which own about 10 percent of Walgreen's common stock, already have agreed to support the merger, according to the Walgreen proxy.