AmerisourceBergen, a global pharmaceutical services company based in Valley Forge, Penn., has signed a three year agreement to supply approximately $18.5 billion in pharmaceuticals to Express Scripts on an annual basis, effective October 1, 2012.

“We are honored that Express Scripts has chosen AmerisourceBergen to supply the brand pharmaceuticals it needs for its recently combined mail order and specialty pharmacy business,” said Steven H. Collis, president and CEO of AmerisourceBergen.

The contract is expected to contribute approximately 23% of the company’s revenues, and about 3% of its earnings per share. The contract award has no impact on the company’s expectations for fiscal 2012 or on its preliminary expectations for fiscal 2013 which it disclosed on July 26, 2012.