Mr. Rein has been instrumental in the early capitalization of high technology ventures as well as the facilitation and development of strategic alliances, mergers and acquisitions, joint ventures, leveraged buyouts and management buyouts. Mr. Rein was an investor with Avici, Zamba, Microtune, Unisite, Amdocs, Dagaz, Sybase, Intuit, Ungerman Bass, Worldgate Communications, Checkfree Holdings, Compaq Computers, Attachmate, Delphi, Josten's Learning, Allegiance Telecommunications amongst numerous other investments and was a founder of Dama Telecommunications. He serves on the boards of ConceptWave, Conduit, Monetor and  Registri and is a limited partner in Welsh Carson Anderson & Stowe.

Mr. Rein is also chairman of the Rein Foundation, a philanthropic organization focused on the advancement of education and learning. He holds an MS in Talmudic Law from Beth Medrash Gohova.