Walgreens is buying rival Rite Aid for about $9.41 billion in cash, creating a drugstore giant with nearly 18,000 stores around the world. The deal combines the largest and third-largest U.S. drugstore chains, based on store counts.

And it makes one of the world’s largest pharmaceutical buyers even bigger at a time when other key health care players like insurers and drugmakers also are expanding through multi-billion dollar deals.