Wall Street's credit-derivatives traders, who before the financial crisis commanded $2 million of annual pay, are being replaced by machines as banks cut costs and heed new regulations.

UBS AG, Switzerland's biggest bank, fired its head of credit-default swaps index trading, David Gallers, last week, with no plan to fill the position, according to two people familiar with the matter. Instead, the bank replaced Gallers with computer algorithms that trade using mathematical models, said the people, who asked not to be identified because moves are private.

UBS joins Barclays Plc, Credit Suisse Group AG and Goldman Sachs Group Inc. in using computer programs to trade financial instruments that once generated some of their biggest fees. With regulators preparing rules under the 2010 Dodd-Frank financial reform that will push swaps toward exchange-like systems to improve transparency, credit dealers are going digital as automated trading makes humans too expensive.