Insull served as personal secretary to Thomas Edison, eventually taking control of most of the Edison General Electric Company. His experience in the electric industry and keen optimism for its future led Insull to his development of an enormous utility holding company with assets in excess of two billion dollars. His pyramid of holding companies collapsed due to the combination of his highly leveraged position and a September 1931 stock market crash. In April of 1932, the top Insull companies went into receivership, thus ending the reign of one of America's leading symbols of prestige and business success of the 1920's. Insull's signature is rarely encountered on stocks/bonds other than his Louisville and Northern Railway and Lighting Company.