CVS Health offers a diverse set of healthcare services. Its roots are in its retail pharmacy operations, where it operates around 9,000 stores primarily in the US. CVS is also a large pharmacy benefit manager (acquired through Caremark), processing about 2 billion adjusted claims annually. It operates a top-tier health insurer (acquired through Aetna) through which it serves about 27 million medical members. The acquisition of Oak Street Health added primary care services to the mix, which could have significant synergies with all existing business lines.