Complex sentence: In 1986 he returned to his the Wharton School, while taking the part time position of Director of Research and Chief Economist at AIG-Financial Products, the experience from which helped him develop the first financial engineering course to be offered at Upenn.
Split into simpler sentences: In 1986 he returned to the Wharton School, while taking the part time position of director of research and chief economist at American International Group. He used his experience there to develop the first financial engineering course to be offered at Upenn.