The US's largest public pension fund, California Public Employees' Retirement System, said it earned a 12.5% net return on investments in 2010, the second straight year with a double-digit percentage climb.

The fund, commonly known as Calpers, said its private equity programme had the best performance of all asset classes with a 21.5% return. The S&P 500 index had a 15% return last year, while the Dow Jones Industrial Average's was 14%.