Express Scripts claims to be the No. 1 company in the mail order prescription business. In this video, Fool analyst Jim Mueller explains the Express Scripts business and the three things investors need to watch. Mail order prescriptions are attracting the attention of big pharma and generics alike, and how well Express Scripts penetrates these markets is critical to its future success.

Austin Smith owns shares of Pfizer. Jim Mueller has no position in any stocks mentioned. The Motley Fool recommends Express Scripts. The Motley Fool owns shares of Express Scripts. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.