Walgreens plans to close a significant number of its approximately 8,600 locations in the U.S. as part of a multiyear optimization program aimed at improving the struggling pharmaceutical chain’s performance.

Although the company has not specified the exact number of closures, CEO Tim Wentworth announced that changes are imminent for about 25% of its underperforming stores.

The closures will target locations that are unprofitable, too close to one another, or facing theft issues.

Wentworth indicated that the closures will occur over the next three years, with most affected employees offered positions at other stores, CNN has reported.

Walgreens’ shares dropped 20% to their lowest level in decades following the announcement, and the company has also reduced its full-year profit outlook, citing inflation’s impact on the drug store business.

Written by B.C. Begley