Gradually, though, many of the Black-Scholes-Merton model's assumptions gained greater verisimilitude. Stock borrowing became easier, for example as the trust departments of U.S. banks began to be prepared to lend out stocks owned by their clients (Faulkner 2004, p. 47), and the balance of market power began to shift, with borrowers obtaining increasing proportions of the interest on the proceeds of short sales (Thorp interview). A protracted struggle over the New York Stock Exchange's fixed commissions ended with their abolition in May 1975. The speed of transmission of stock prices from New York to Chicago was increased, and better communications and increasing automation made it quicker and easier to adjust the replicating portfolio.

Donald MacKenzie, An Engine, Not a Camera, loc. 741