Business History Review
This article analyzes the evolution of the Philadelphia Stock Exchange (PHLX), America's oldest stock exchange, from 1950 through 2000. PHLX was able to compete against the much larger New York Stock Exchange (NYSE) because it exploited loopholes created by fixed minimum trading commissions prior to 1975. After the liberalization of commissions, the PHLX competed against the NYSE by offering automated executions that met the needs of discount brokers. It also moved early to trade equity options and developed the first exchange-based market for foreign currency options.
John P. Caskey.
"The Philadelphia Stock Exchange: Adapting To Survive In Changing Markets".
Business History Review.