East Resources, Inc. was formed by Terrence M. Pegula in 1983. The company explored for and produced oil & gas, primarily in the Appalachian Basin, and it acquired a significant position in the Marcellus Shale play in Pennsylvania. In July of 2010, the company, through the sale of an affiliate, East Resources Management, LLC, sold its Marcellus Shale and other assets in Pennsylvania, New York, and Colorado to an affiliate of Shell Oil Company. The company's principal place of business is now located in Boca Raton, Florida.