Connecticut Avenue Securities (CAS)

The benchmark for U.S. mortgage credit

As the largest manager of residential mortgage credit, Fannie Mae sets the standard for managing credit risk throughout the life cycle of a mortgage – continuously innovating to reduce default risk and credit losses.

Through Connecticut Avenue Securities® (CAS), institutional investors can invest side-by-side with Fannie Mae in our geographically diverse credit book of business. The 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).

Developing a broad and deep market

Since our first CAS issuance in October 2013, Fannie Mae has built a robust market sector for mortgage credit. Our offering of industry-leading tools and capabilities have helped to build a broad and diverse investor base. To allow institutional investors to evaluate the CAS program, we provide:

Through CAS, we have developed a liquid market for single-family mortgage credit risk.

A geographically diverse reference pool

The reference pools consist of conventional 30-year fixed-rate mortgage loans recently securitized into Fannie Mae MBS:

  • large and highly diversified reference pools, offering broad exposure to the US housing market
  • reference pools are composed of loans that are originated to meet Fannie Mae's rigorous underwriting and eligibility criteria
  • Fannie Mae's innovative quality control process applies to all loans included in each reference pool – we provide ongoing credit risk management oversight throughout the life of each loan
  • reference pools for each transaction are divided into two loan groups based on original loan-to-value (LTV) ratios – each pool will generally include loans with original LTV ratios between 60.01% and 80.00% or loans with original LTV ratios between 80.01% and 97.00%

The CAS REMIC, an innovative deal structure

Fannie Mae introduced the industry's leading innovation in mortgage credit risk transfer, the CAS REMIC that furthers the ability to broaden the investor base. CAS deal structures from 2018-R07 forward are known as CAS REMICs, issued by a bankruptcy remote trust. The CAS REMIC:

  • Satisfy all of the REIT income and asset tests for tax purposes
  • Removes tax withholding restrictions for non-U.S. investors in all tranches
  • Helps insulate investors from potential future counterparty risk exposure to Fannie Mae
  • Simplifies and aligns tax treatment of CAS with other mortgage related securities

The CAS REMIC retains key features of the CAS program to support consistency of the program, including:

  • notes are par-priced, uncapped 1-month LIBOR floating rate notes
  • principal and interest on the notes is paid by the trust to note holders on a monthly basis
  • notes have a defined final maturity of either 10 or 12.5 years
  • payment on the securities is based on the performance of a "reference pool" of loans that were recently securitized into Fannie Mae MBS
  • CAS investors may bear losses if loans in the reference pools experience losses

CAS REMIC deal structures are similar to a typical residential mortgage backed securitization:

  • CAS notes utilize a senior/subordinate structure in which credit protection is provided by the more junior notes to the more senior notes in priority order
  • as principal is repaid on the loans in the reference pool, a corresponding amount of principal is repaid to the noteholders
  • if loans in the reference pool default and experience losses, the CAS REMIC notes also experience losses – losses are applied first to write down the most junior notes, then allocated to the remaining notes in reverse sequential order

Fannie Mae retains a vertical slice of each CAS REMIC transaction to ensure aligned interest with investors.

CAS REMIC deal structure diagram

Transactions prior to CAS 2018-R07, known as the "C" series (e.g., CAS 2018-C06) are unguaranteed and unsecured debt securities of Fannie Mae. The "C" series is unlike standard Fannie Mae debt as CAS investors may bear losses if loans in the reference pools experience losses.

Learn more

Are you an institutional investor who wants to learn more about our CAS program? We would love to connect with you. Contact us here.