Walgreens Boots Alliance Inc. has frozen pay for senior U.S. executives as the drugstore chain undertakes a $1.5 billion cost-cutting program, the company said at an analyst meeting Wednesday.

The company will also reorganize corporate and field operations and revamp its technology, which along with the store closings will help cut an additional $500 million in costs by the end of fiscal 2017.

Chinese hackers stole social security numbers, names and addresses from 4.5 million patients of Community Health Systems Inc., the second-biggest for-profit U.S. hospital chain.