Fannie Megas® (Megas) are single-class pass-through securities in which the underlying collateral are groups of existing Fannie Mae MBS or other Fannie Megas. The cash flows from the underlying MBS and/or Megas provide the cash flows for the Mega pool. The securities that back a Fannie Mega may be single-family or multifamily Fannie Mae MBS or previously issued Fannie Mega pools. Fannie Megas issued prior to Jan. 1, 2006, also may have been backed by Ginnie Mae securities.