Calling the $1.72 trillion international stock loan market good for the banks that do the lending but “bad for virtually everyone else,” a trio of pension funds filed a class action suit against six of the world’s largest financial firms Thursday.

The Iowa Public Employees’ Retirement System, Orange County Employees Retirement System and Sonoma County Employees’ Retirement Association accused the banks of conspiring to violate federal antitrust laws “to keep stock loan trading frozen in an inefficient and opaque [over-the-counter] market in order to preserve their privileged position as intermediaries on every trade,” according to the suit brought in the U.S. District Court for the Southern District of New York.