 Walgreens is finalizing a plan to fix its U.S. business that could result in closing hundreds of additional stores over the next three years. CEO Tim Wentworth told analysts on Thursday that changes are imminent for about 25% of the company's stores, which he said were underperforming. He said we're at the point where the current pharmacy model is not sustainable, and the challenges in our operating environment require us to approach the market differently.