ARM MBS Subtypes

Adjustable-rate (ARM) Fannie Mae MBS Subtypes are alphanumeric codes that identify ARM product characteristics such as index, initial fixed-rate period, rate and payment adjustment frequency and caps, convertibility, and other features.

The following files contain certain key features of adjustable-rate mortgages backing Fannie Mae MBS. These features constitute the particular subtype of an adjustable-rate Fannie Mae MBS pool identified in the matrix file. Subtypes are only applicable to adjustable-rate securities. The latest subtype definitions are available after 7 a.m. ET, and will include any new subtypes created the prior day.

Our consolidated listings of all Single-Family (SF) and Multifamily (MF) subtypes and attributes are available in .csv format.