Securities Transfer Authority Failure Through Credit Ratings Assigned Without Underlying Asset Verification in Mortgage-Backed Securities

Credit ratings from Moody's, S&P, and Fitch function as the primary credential by which fixed-income securities are evaluated by investors, regulators, and financial institutions. Regulatory frameworks require banks, insurance companies, pension funds, and money market funds to hold securities meeting minimum credit rating thresholds. An AAA rating — the highest available — certifies that the security presents minimal credit risk. For structured finance products, the rating is assigned based on the agency's assessment of how the security's cash flow structure distributes risk across different tranches, using mathematical models that project default rates, loss severity, and correlation assumptions.

During the mid-2000s, investment banks constructed mortgage-backed securities and collateralized debt obligations from pools of residential mortgages, including substantial proportions of subprime loans — mortgages issued to borrowers with weak credit histories, limited documentation, or both. The banks submitted the proposed security structures to the rating agencies, which ran their models and assigned ratings to each tranche. The senior tranches of these securities routinely received AAA ratings. The agencies were paid by the issuers — the investment banks — for each rating assigned, creating a revenue model in which the entity seeking the credential paid the entity granting it.

Beginning in 2006, mortgage default rates — particularly among subprime borrowers — began rising sharply, exceeding the assumptions embedded in the rating agencies' models. By mid-2007, the agencies initiated mass downgrades of structured finance securities, with thousands of tranches losing their investment-grade ratings within months. Securities that had been rated AAA — the same rating assigned to U.S. Treasury bonds — were downgraded to junk status. Over 90% of AAA-rated subprime RMBS tranches issued in 2006 and 2007 were eventually downgraded.

The downgrades triggered cascading consequences across the global financial system. Institutions holding the securities faced capital shortfalls. Funds required to hold investment-grade securities were forced to sell. Counterparties who had written insurance against defaults — notably AIG — faced obligations they could not meet. The resulting financial crisis produced the deepest global recession since the 1930s, required unprecedented government interventions including the $700 billion Troubled Asset Relief Program, and destroyed an estimated $10 trillion or more in global economic output.

The rating agencies evaluated the structure of the securities — the mathematical architecture determining how cash flows and losses would be distributed across tranches. The models assumed default rates, loss severity, and correlation figures derived from historical data on mortgage performance. The agencies did not independently verify the quality of the individual mortgages underlying the securities. They did not examine whether the loans were originated with proper documentation, whether borrower incomes were verified, or whether the appraisals supporting the loan values were accurate. The rating certified the structure's resilience to projected losses. It did not verify whether the projected losses reflected the actual risk of the underlying loans.

The issuer-pays model compounded the structural gap. The investment banks constructing the securities were also the agencies' clients and revenue source. Internal communications later revealed by congressional investigations showed agency employees acknowledging pressure to maintain market share by delivering favorable ratings. An agency that applied more conservative assumptions risked losing business to a competitor willing to rate the same structure more favorably. The rating functioned as the credential that enabled the security to be sold to regulated investors. The credential was issued by entities whose revenue depended on the volume of credentials issued, paid for by the entities seeking those credentials, based on models that evaluated the instrument's architecture without verifying the quality of its foundation.

The Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010 established the SEC Office of Credit Ratings to oversee rating agencies, required enhanced disclosure of rating methodologies and performance, and reduced regulatory reliance on credit ratings. The SEC adopted rules requiring rating agencies to disclose conflicts of interest and establish internal controls against commercial influence on rating decisions. S&P paid $1.375 billion to settle federal and state claims that it had inflated ratings to win business. Moody's paid $864 million in similar settlements. The Financial Crisis Inquiry Commission concluded that the rating agencies were essential enablers of the financial crisis, assigning the ratings that made the sale of the securities possible.