A key step in the process of creating and ultimately selling an RMBS is the issuance of
a credit rating for each of the tranches issued by a trust. The arranger of the RMBS
initiates the ratings process by sending the credit rating agency a range of data on each
of the loans to be held by the trust (e.g., principal amount, geographic location of the
property, credit history and FICO score of the borrower, ratio of the loan amount to the
value of the property and type of loan: first lien, second lien, primary residence,
secondary residence), the proposed capital structure of the trust and the proposed
levels of credit enhancement to be provided to each RMBS tranche issued by the trust.
A lead analyst at the rating agency is assigned responsibility for analyzing the loan pool,
proposed capital structure, and proposed credit enhancement levels, and for ultimately
formulating a ratings recommendation for a rating committee. The credit rating for each
rated tranche indicates the credit rating agency‘s view as to the creditworthiness of the
debt instrument. Creditworthiness is assessed in terms of the likelihood that the issuer
would default on its obligations to make interest and principal payments on the debt
instrument.
By regulation, corporate credit unions are only allowed to invest in highly rated
securities. Corporate credit unions have traditionally used these securities as part of
their overall balance sheet management in meeting their member liquidity needs.
Historically, the securities could be readily sold in the market or used for collateralized