WASHINGTON (AP) - Fannie Mae filed a lawsuit Thursday against nine major banks that alleges the mortgage giant lost hundreds of millions of dollars after they rigged a key global interest rate.

WASHINGTON (AP) Fannie Mae filed a lawsuit Thursday against nine major banks that alleges the mortgage giant lost hundreds of millions of dollars after they rigged a key global interest rate.

The banks include Bank of America, Citigroup, JPMorgan Chase and others that set the London interbank offered rate, or LIBOR. It is the basis for trillions of dollars in contracts, including mortgages and bonds.

Fannie claims it suffered $800 million in losses from transactions based on the banks' false submissions of their borrowing costs used to calculate LIBOR.

Four of the banks sued two British, one Swiss and one Dutch have been fined a total $3.6 billion by U.S. and British regulators for manipulating LIBOR.

Fannie's smaller sibling Freddie Mac filed similar suits against 15 LIBOR-setting banks in March.