Fannie Mae, the US mortgage giant, is being sued by a large US shareholder over planned multi-million dollar compensation payouts to its top two executives, who were ousted from the firm following the discovery of serious accounting irregularities.

The Wayne County Employees' Retirement System, a Michigan-based pension fund, asked the US Court for the District of Columbia for a restraining order freezing compensation payments to Franklin Raines, former chief executive and Timothy Howard, former chief financial officer of Fannie Mae, according to court documents.