With his partner, Fred Wilson, Jerry launched Flatiron Partners in August 1996. Flatiron became one of the most successful, investment programs in the New York City area, growing into an investment fund that focused primarily on follow-on investing, with investments in notable dot-com bubble successes and failures, including Alacra, comScore Networks, Yoyodyne, GeoCities, Kozmo.com, New York Times Digital, PlanetOut, Return Path, Gamesville Inc, Scout electromedia, Standard Media International, Starmedia, and VitaminShoppe.com. The firm's 1996 fund capitalized at $150 million with two investors: SOFTBANK Technology Ventures and Chase Capital Partners, the private-equity arm of Chase Manhattan Corp. The firm later raised another fund capitalized at $500 million with Chase Capital Partners as the sole active LP. On July 2, 2001, Colonna was named to the Advisory Board of Silicon Alley Entrepreneurs Club. In 2001 Colonna and Wilson shut down Flatiron.