Koppelman rose rapidly in the world of finance and banking, becoming executive vice-president and chief operating officer of D.H. Blair and Co., Inc. In 1984, he became president of Eastlake Securities, Inc., which merged into J.P. Morgan, where he now serves as vice president in Private Client Services.
Koppelman sits on the board of governors of Hillel International and has served as president of Brooklyn College Hillel. The Koppelman Professorships, which Koppelman endowed in 1994, recognize outstanding service by members of the Brooklyn College faculty. Koppelman was named Brooklyn College Alumnus of the Year in 1994 and was awarded a Presidential Medal in 1995. In 2011, his generous support made it possible for the Brooklyn College Foundation to purchase a 24,000-square-foot property adjacent to the college.