File:Impaired Securities.GIF|thumb|450px|source: Final Report of the National Commission on the Causes of the Financial and Economic Crisis in the United States, p.229, figure 11.4 Credit rating agencies came under scrutiny following the mortgage crisis for giving investment-grade, "money safe" ratings to
securitized mortgages (in the form of securities known as
mortgage-backed securities (MBS) and
collateralized debt obligations (CDO)) based on "non-prime"—subprime or Alt-A—mortgages loans. Demand for the securities was stimulated by the large global pool of fixed income investments which had doubled from $36 trillion in 2000 to $70 trillion by 2006—more than annual global spending—and the low interest rates from competing fixed income securities, made possible by the low interest rate policy of the U.S.
Federal Reserve Bank for much of that period. These high ratings encouraged the flow of global investor funds into these securities funding the housing bubble in the US. Earlier traditional and more simple "prime" mortgage securities were issued and guaranteed by
Fannie Mae and
Freddie Mac—
"enterprises" sponsored by the Federal government. Their safety wasn't questioned by conservative money managers. Non-prime private label mortgage securities were neither made up of loans to borrowers with high credit ratings nor insured by a government enterprise, so issuers used an innovation in securities structure to get higher agency ratings. They pooled debt and then "sliced" the result into "
tranches", each with a different priority in the debt repayment stream of income. The most "senior" tranches highest up in priority of revenue—which usually made up most of the pool of debt—received the triple A ratings. This made them eligible for purchase by the pension funds and money market funds restricted to top-rated debt, and for use by banks wanting to reduce costly capital requirements under
Basel II. The complexity of analyzing the debt pool mortgages and tranche priority, and the position of the Big Three credit rating agencies "between the issuers and the investors of securities", is what "transformed" the agencies into "key" players in the process, according to the
Financial Crisis Inquiry Report. From 2000 to 2007, Moody's rated nearly 45,000 mortgage-related securities By December 2008, there were over $11 trillion structured finance securities outstanding in the US
bond market debt.
CDOs Rating agencies were even more important in disposing of the MBS tranches that could not be rated triple A. Although these made up a minority of the value of the MBS tranches, unless buyers were found for them, it would not be profitable to make the security in the first place. And because traditional mortgage investors were risk-averse (often because of
SEC regulations or restrictions in their charters), these less-safe tranches were the most difficult to sell. To sell these "mezzanine" tranches, investment bankers pooled them to form another security—known as a collateralized debt obligation (CDO). Though the raw material of these "obligations" was made up of BBB, A−, etc. tranches, the CRAs rated 70% to 80% of the new CDO tranches triple A. The 20–30% remaining mezzanine tranches were usually bought up by other CDOs, to make so-called "
CDO-Squared" securities which also produced tranches rated mostly triple A by rating agencies. This process was disparaged as a way of transforming "dross into gold" or "ratings laundering" by at least some business journalists. Trust in rating agencies was particularly important for CDOs for another reason—their contents were subject to change, so CDO managers "didn't always have to disclose what the securities contained". This lack of transparency did not affect demand for the securities. Investors "weren't so much buying a security" as they "were buying a triple-A rating", according to business journalists
Bethany McLean and
Joe Nocera. Still another structured product was the "synthetic CDO". Cheaper and easier to create than original "cash" CDOs, these securities did not provide funding for housing. Instead synthetic CDO-buying investors were in effect providing insurance (in the form of "
credit default swaps") against mortgage default. Synthetics "referenced" cash CDOs, and rather than providing investors with interest and principal payments from MBS tranches, they paid insurance premium-like payments from credit default swap "insurance". If the referenced CDOs defaulted, investors lost their investment, which was paid out as insurance. Because synthetics referenced another (cash) CDO, more than one—in fact numerous—synthetics could be made to reference the same original. This multiplied the effect if a referenced security defaulted. Here again the giving of triple-A ratings to "large chunks" of synthetics by the rating agencies was crucial to the securities' success. The buyer of synthetic tranches (who often went on to lose his investment) was seldom an analyst "who had investigated the mortgage-backed security", was aware of deteriorating
mortgage underwriting standards, or that the payments they would receive were often coming from investors betting against mortgage-backed security solvency. Rather, "it was someone who was buying a rating and thought he couldn't lose money."
Downgrades and writedowns By the end of 2009, over half of the collateralized debt obligations by value issued at the end of the housing bubble (from 2005–2007) that rating agencies gave their highest "triple-A" rating to, were "impaired"—that is either written-down to "junk" or suffered a "principal loss" (i.e. not only had they not paid interest but investors would not get back some of the principal they invested). The Financial Crisis Inquiry Commission estimates that by April 2010, of all mortgage-backed securities Moody's had rated triple-A in 2006, 73% were downgraded to junk. Mortgage underwriting standards deteriorated to the point that between 2002 and 2007 an estimated $3.2 trillion in loans were made to homeowners with bad credit and undocumented incomes (e.g., subprime or
Alt-A mortgages) Image:MBS Downgrades Chart.png|thumb|350px|MBS Credit Rating Downgrades, By Quarter Adding to the financial chain reaction were regulations—governmental or internal—requiring some institutional investors to carry only investment-grade (e.g., "BBB" and better) assets. A downgrade below that meant forced asset sales and further devaluation. ==Criticism==