Abstract:A Trade Practices Commission ruling, which came into effect on 1 April 1984, prohibited the Australian Associated Stock Exchanges (now known as the Australian Stock Exchange) from fixing brokerage fees. The expected consequence was a move to competitive pricing. Specifically, it was expected that brokerage fees would more accurately reflect the costs of providing brokerage services. This study analyses the evolution of the pricing mechanism since deregulation. In particular, it tests the influence of factors such as order size, broker quality, broker size, inventory costs, search costs, broker specialisation and broker learning on brokerage fees.