Exterior Office Building

Connecticut Avenue Securities

Connecticut Avenue Securities (CAS) is the benchmark for U.S. mortgage credit.

The Connecticut Avenue Securities® (CAS) program provides an opportunity to invest in a portion of the credit risk that Fannie Mae retains when we guarantee single-family mortgage-backed securities (MBS).

As of Q1 2022, $1.78T of unpaid principal balance of Single-Family mortgage loans is partially covered through CAS transactions, measured at the time of the transactions. 

In April 2018, SIFMA's TBA Guideline Steering Committee confirmed via a vote that it has not identified any issues that would impair the TBA eligibility of MBS under this new structure.

As a result, Fannie Mae released an updated Single-Family MBS Prospectus, effective for fixed-rate and adjustable-rate mortgage single-family pools with issue dates on or after May 1, 2018. These pools are issued under our Amended and Restated 2016 Single-Family Master Trust Agreement.