US floor brokers have become unsettled by the New York Stock Exchange's (NYSE's) proposed extension of its automated trading system after the exchange bowed to pressure from institutions to change.

Floor brokers are blaming "speed freak" hedge funds, which need immediate execution, for pressuring the NYSE to improve electronic trading. However, the exchange has faced heavier pressure from the US's largest fund managers, such as Fidelity and Calpers. Calpers has sued the exchange and its specialist marketmaking firms over using knowledge of the order book to defraud investors. Last week, the Securities and Exchange Commission (SEC) told specialists they had to settle the allegations by Tuesday or face federal prosecution.