OREANDA-NEWS. S&P Global Ratings today completed its review of 74 classes from 14 U. S. residential mortgage-backed securities (RMBS) transactions issued between 2001 and 2007. The review yielded 28 upgrades, 41 affirmations, four withdrawals, and one discontinuance.

All of the transactions in this review were issued between 2001 and 2007 and are supported by a mix of fixed - and adjustable-rate Alternative-A mortgage loans, which are secured primarily by first liens on one - to four-family residential properties.

With respect to insured obligations, where we maintain a rating on the bond insurer that is lower than what we would rate the class without bond insurance, or where the bond insurer is not rated, we relied solely on the underlying collateral's credit quality and the transaction structure to derive the rating on the class. As discussed in our criteria, "The Interaction Of Bond Insurance And Credit Ratings," published Aug. 24, 2009, the rating on a bond-insured obligation will be the higher of the rating on the bond insurer and the rating of the underlying obligation, without considering the potential credit enhancement from the bond insurance.

The classes listed below are insured as follows:TBW Mortgage-Backed Trust 2006-6's class A-4 ('CCC (sf)') and class A-5A ('CCC (sf)'), insured by MBIA Insurance Corp. ('CCC');Impac Secured Assets Corp.'s series 2001-8 class A-6 ('AA+ (sf)'), insured by MBIA Insurance Corp. ('CCC'); andTBW Mortgage-Backed Trust 2007-2's class A-4-B ('AA (sf)'), insured by Assured Guaranty Municipal Corp. ('AA').Seven other classes in this review were insured by a rated insurance provider when the deal was originated, but S&P Global Ratings has since withdrawn the rating on the insurance provider of those classes.

ANALYSISAnalytical ConsiderationsWe incorporate various considerations into our decisions to raise, lower, or affirm ratings when reviewing the indicative ratings suggested by our projected cash flows. These considerations are based on transaction-specific performance or structural characteristics (or both) and their potential effects on certain classes.

UPGRADESWe raised our ratings on 28 classes, including 21 ratings that were raised three or more notches. Our projected credit support for the affected classes is sufficient to cover our projected losses for these rating levels. The upgrades reflect one or more of the following:Improved collateral performance/delinquency trends;Increased credit support relative to our projected losses;A change in payment allocation due to failing performance triggers; and/orThe class' expected short duration. AFFIRMATIONSWe affirmed our ratings on 24 classes in the 'AAA' through 'B' rating categories. These affirmations reflect our opinion that our projected credit support on these classes remains relatively consistent with our prior projections and is sufficient to cover our projected losses for those rating scenarios.

For certain transactions, we considered specific performance characteristics that, in our view, could add volatility to our loss assumptions and, in turn, to the ratings suggested by our cash flow projections. When our model recommended an upgrade, we either limited the extent of our upgrade or affirmed our ratings on those classes to account for this uncertainty and promote ratings stability. In general, these classes have one or more of the following characteristics that limit any potential upgrade:Insufficient subordination, overcollateralization, or both;Delinquency trends;Historical interest shortfalls; and/orLow priority in principal payments. In addition, some of the transactions have failed their delinquency triggers, resulting in reduced--or a complete stop of--unscheduled principal payments to their subordinate classes. However, these transactions allow for unscheduled principal payments to resume to the subordinate classes if the delinquency triggers begin passing again. This would result in eroding the credit support available for the more senior classes. Therefore, we affirmed our ratings on certain classes in these transactions even though these classes may have passed at higher rating scenarios.

The ratings affirmed at 'CCC (sf)' or 'CC (sf)' reflect our belief that our projected credit support will remain insufficient to cover our 'B' expected case projected losses for these classes. Per "Criteria For Assigning 'CCC+', 'CCC', 'CCC-', And 'CC' Ratings," published Oct. 1, 2012, the 'CCC (sf)' affirmations reflect our view that these classes are still vulnerable to defaulting, and the 'CC (sf)' affirmations reflect our view that these classes remain virtually certain to default.

We also affirmed the 'AA+ (sf)' rating on class A-IO from Impac Secured Assets Corp. series 2001-8. The rating action reflects the application of our interest-only (IO) criteria (see "Global Methodology For Rating Interest-Only Securities," published April 15, 2010), which provide that we will maintain the current rating on an IO class until all of the classes that the IO security references are either lowered to below 'AA - (sf)' or have been retired--at which time we will withdraw these IO ratings.

WITHDRAWALSWe withdrew our ratings on classes 3-A1, 3-A2, 3-PO, and 3-B1 from Citigroup Mortgage Loan Trust Inc. series 2005-1 because the related pool has a small number of loans remaining. Once a pool has declined to a de minimis amount, we believe there is a high degree of credit instability that is incompatible with any rating level.

DISCONTINUANCESWe discontinued our ratings on class 1-A3 from Structured Asset Securities Corp. Mortgage Loan Trust 2005-4XS because this class has been paid in full as of June 2016.

ECONOMIC OUTLOOKWhen determining a U. S. RMBS collateral pool's relative credit quality, our loss expectations stem, to a certain extent, from our view of how the loans will behave under various economic conditions. S&P Global Ratings' baseline macroeconomic outlook assumptions for variables that we believe could affect residential mortgage performance are as follows:

An overall unemployment rate of 4.8% in 2016;Real GDP growth of 2.0% for 2016;The inflation rate will be 2.2% in 2016; andThe 30-year fixed mortgage rate will average about 3.7% in 2016.Our outlook for RMBS is stable. Although we view overall housing fundamentals positively, we believe RMBS fundamentals still hinge on additional factors, such as the ultimate fate of modified loans, the propensity of servicers to advance on delinquent loans, and liquidation timelines.

Under our baseline economic assumptions, we expect RMBS collateral quality to improve. However, if the U. S. economy were to become stressed in line with S&P Global Ratings' downside forecast, we believe that U. S. RMBS credit quality would weaken. Our downside scenario reflects the following key assumptions:Total unemployment will tick up to 4.9% for 2016;Downward pressure causes GDP growth to fall to 1.8% in 2016;Home price momentum slows as potential buyers are not able to purchase property; andWhile the 30-year fixed mortgage rate remains a low 3.7% in 2016, limited access to credit and pressure on home prices will largely prevent consumers from capitalizing on these rates.