Walgreen's top financial officer is leaving the largest U.S. drugstore chain as it nears a key decision about its future that could involve a politically touchy overseas reorganization.

Walgreen said Monday it will replace Wade Miquelon with former Kraft Foods executive Timothy McLevish as executive vice president and chief financial officer, effective immediately.

Miquelon, 49, had served as a senior leader in the drugstore chain's multibillion-dollar collaboration with Swiss health and beauty retailer Alliance Boots. He had joined the board of Alliance Boots, which runs the largest drugstore chain in the United Kingdom. A Walgreen spokesman said Miquelon was not terminated and would continue to work temporarily for Walgreen as an adviser, but he is leaving the board of Alliance Boots.

Walgreen Co., which runs more than 8,200 drugstores, bought a 45 percent stake in Alliance Boots a few years ago and will announce soon whether it plans to buy the rest. The Deerfield, Illinois, company also is considering an overseas combination called an inversion with Alliance Boots that could reduce its U.S. corporate tax bill.

In an inversion, a U.S. corporation reorganizes in another country with a lower tax rate, often as part of a new company created through a combination with another business. Dozens of U.S. companies have completed inversions in recent years, and they're especially popular with drugmakers that have extensive overseas operations. But members of Congress and President Barack Obama have raised concerns about the tax revenue the federal government is losing as a result of these deals.

Walgreen has said it expects to decide early this month about its next step with Alliance Boots.

CEO Greg Wasson said in a statement Monday that McLevish was coming on board as Walgreen prepares "to embark on our journey to create the first global pharmacy-led, health and wellbeing enterprise."

McLevish, 59, had been executive vice president and CFO for Kraft Foods Group Inc. He holds a master's degree in business administration from Harvard University.

Walgreen shares added 96 cents, or 1.4 percent, to $71.49 in Monday morning trading, while broader indexes were little changed.