The California State Teachers' Retirement System (Calstrs), one of the biggest investors in private equity, has criticised the listing of buy-out groups, saying they could harm long-term investors and disrupt the ability of companies to make deals.

Christopher Ailman, chief investment officer of the $170bn-plus pension fund, told the Financial Times that listed buy-out groups could face a conflict between the short-term demands of shareholders and long-term returns sought by pension funds.