In 1970, William Manning founded Manning & Napier with business partner Bill Napier, becoming a leading investment firm in America. In 1992, he founded Manning Ventures, Inc., an investment firm focused on software and technology.

Manning co-founded Kent Displays, Inc. with Dr. Doane in 1993. His vision to grow and support the emerging display industry pushed Kent Displays to become the leader in display technology that it is today.