Credit rating agencies play a crucial role in the subprime lending market by assigning ratings to subprime mortgage-backed securities (MBS). These ratings provide investors with an assessment of the creditworthiness and risk associated with these securities. When assigning ratings to subprime MBS, credit rating agencies consider several key factors that help them evaluate the quality and potential performance of these securities. The factors considered can be broadly categorized into three main areas: credit quality, collateral, and structural features.
1. Credit Quality:
Credit rating agencies assess the credit quality of subprime MBS by evaluating the underlying mortgage loans and the borrowers' ability to repay. They consider various factors such as:
a. Borrower Creditworthiness: The credit rating agencies analyze the credit profiles of the borrowers, including their credit scores, payment history, and debt-to-income ratios. Higher credit scores and lower debt burdens are generally associated with lower
default risk.
b. Loan-to-Value (LTV) Ratio: The LTV ratio represents the loan amount as a percentage of the property's appraised value. A lower LTV ratio indicates a smaller loan relative to the property's value, which reduces the risk of default.
c. Loan Documentation: The quality of loan documentation is crucial in assessing credit risk. Credit rating agencies evaluate whether the loans have proper documentation, including income verification, employment history, and other relevant information.
d. Loan
Origination Practices: Agencies consider the underwriting standards and practices employed by lenders when originating subprime loans. They assess whether the loans were made based on reasonable and prudent lending criteria.
2. Collateral:
The collateral backing subprime MBS is primarily residential properties. Credit rating agencies evaluate various aspects related to the collateral, including:
a. Property Valuation: Agencies assess the accuracy and reliability of property appraisals to determine if they are consistent with market conditions. Overinflated appraisals can lead to higher default risk.
b. Geographic Concentration: Agencies consider the geographic concentration of the underlying properties. A diversified pool of properties across different regions reduces the risk associated with localized economic downturns.
c. Property Type: The type of property, such as single-family homes, condominiums, or multi-family units, is also taken into account. Different property types may have varying levels of risk and potential for appreciation.
3. Structural Features:
Credit rating agencies analyze the structural features of subprime MBS to assess their
cash flow characteristics and potential risks. Some important factors considered include:
a. Loan Pool Characteristics: Agencies evaluate the size and composition of the loan pool, including the number of loans, their average size, and the distribution of loan types (e.g., fixed-rate, adjustable-rate).
b. Credit Enhancement: The presence of credit enhancement mechanisms, such as overcollateralization, excess spread, or reserve funds, can mitigate the risk of default and loss severity. Agencies assess the adequacy and effectiveness of these enhancements.
c. Payment Priority: The priority of cash flows within the MBS structure is crucial. Credit rating agencies evaluate the order in which different tranches of securities receive
principal and interest payments, considering factors like seniority and subordination.
d. Prepayment Risk: Agencies consider the potential for borrowers to prepay their loans before
maturity. Prepayments can impact the expected cash flows and affect the risk profile of the MBS.
In conclusion, credit rating agencies consider a range of factors when assigning ratings to subprime mortgage-backed securities. These factors include credit quality indicators related to borrower creditworthiness, loan-to-value ratios, loan documentation, and loan origination practices. Collateral-related factors such as property valuation, geographic concentration, and property type are also assessed. Additionally, structural features like loan pool characteristics, credit enhancement mechanisms, payment priority, and prepayment risk play a significant role in determining the ratings assigned to subprime MBS.