Calpers, the largest public pension fund in the US, has launched a landmark lawsuit against the New York Stock Exchange (NYSE) and seven specialist trading firms, accusing them of profiting at the expense of investors.

Calpers has filed civil fraud charges against the NYSE and has invited all other investors in NYSE-listed stocks to join the class action lawsuit. The pension fund is seeking unquantified damages which could run to millions of dollars from the exchange and the seven specialist firms that run the trading floor.