Gregory Wasson

Walgreens CEO Gregory Wasson announced Wednesday that he will step down from his position before the new year, just as America's largest drug store chain prepares to complete a merger with the Switzerland-based Alliance Boots. The company said in a statement that Stefano Pessina, executive chairman of Alliance Boots, will serve as acting CEO, pending a board search for a successor. Walgreens Chairman James Skinner will become Walgreens Boots Alliance's executive chairman.