AdvancePCS was formed in October 2000 when Advance Paradigm, Inc. acquired PCS Health Systems, Inc. from Rite Aid Corporation. The combined companies created the largest pharmacy benefit manager (“PBM”) in the U.S., responsible for managing the prescription drug benefits of over 75 million people, representing over $20 billion in annual drug spending. AdvancePCS was ultimately sold to Caremark in April 2004. The company was based in Irving, Texas.