The announcement that CVS plans to acquire Aetna for US$69 billion raises hope and concerns. The transaction would create a new health care giant. Aetna is the third-largest health insurer in the United States, insuring about 46.7 million people. CVS operates 9,700 pharmacies and 1,000 MinuteClinics. A decade ago, it also purchased Caremark and now operates CVS/Caremark, a pharmacy benefits manager, a type of business that administers drug benefit programs for health plans.