NEW YORK--(BUSINESS WIRE)--Fitch Ratings has taken various rating actions on 6,571 classes in 617 U.S. Alt-A residential mortgage backed security (RMBS) transactions.
Rating Action Summary:
--6,338 classes (97%) affirmed;
--157 classes (2%) upgraded;
--76 classes (1%) downgraded.
In addition, Fitch subsequently withdrew the ratings on 102 classes. Ratings were withdrawn if classes have already defaulted and have no principal balance remaining or if the weighted average number of loans in the pool underlying the class was currently less than 10. Almost all classes with withdrawn ratings were rated 'Dsf' prior to the review.
A spreadsheet detailing the actions can be found on Fitch's website by performing a title search for 'U.S. RMBS Alt A Rating Actions for Dec. 12, 2014' or by clicking the link. In addition, a summary of the mortgage pool and bond analysis can be found by performing a title search for 'RMBS Loss Metrics.'
KEY RATING DRIVERS
The performance of the mortgage loans underlying the Alt A pools analyzed during this review remained stable to slightly positive since the last review. The percentage of loans 60 or more days delinquent fell across all vintages with transactions issued in 2007 seeing the largest improvement. In addition, prepays ticked up slightly with the later vintages experiencing slightly faster rates.
Since the previous review, Fitch's expected loss assumptions have come down across all vintages. The decline in expected losses is driven both by the improved collateral performance and recent revisions that Fitch has made to its loan loss model. While the model's core methodology has not materially changed, Fitch has made revisions to its home price assumptions and has made several key enhancements to better reflect recent probability of default and loss severity trends. A description of the changes can be found in the report 'U.S. RMBS Loan Loss Model Criteria.'
Projected loss severities have declined across all rating stresses due to updated market value decline assumptions. On average, projected losses declined roughly 8% in the base case with pre 2005 vintage transactions seeing the smallest decreases and 2007 vintage deals seeing the largest.
The improving collateral trends and lower loss assumptions have led to a slightly higher number of upgrades than downgrades for this review. The lower loss assumptions provided the greatest benefit to non-investment grade classes. The number of upgrades for investment grade classes was limited due to long projected months to payoff and the increased tail risk associated with it. Most of the downgrades affected ratings that were already distressed as default becomes more imminent. Downgrades of investment grade classes were primarily caused by rating caps due to low remaining loan counts. As a whole, ratings within the sector were stable as more than 95% of classes were affirmed at their current rating.
A detailed list of Fitch's updated probability of default, loss severity, and expected loss can be found by performing a title search for 'RMBS Loss Metrics' at 'www.fitchratings.com'. The report provides a summary of base-case and stressed scenario projections.
Fitch's analysis includes rating stress scenarios from 'CCCsf' to 'AAAsf'. The 'CCCsf' scenario is intended to be the most-likely base-case scenario. Rating scenarios above 'CCCsf' are increasingly more stressful and less-likely to occur. Although many variables are adjusted in the stress scenarios, the primary driver of the loss scenarios is the home price forecast assumption. In the 'Bsf' scenario, Fitch assumes home prices decline 10% below their long-term sustainable level. The home price decline assumption is increased by 5% at each higher rating category up to a 35% decline in the 'AAAsf' scenario.
In addition to increasing mortgage pool losses at each rating category to reflect increasingly stressful economic scenarios, Fitch analyzes various loss-timing, prepayment, loan modification, servicer advancing, and interest rate scenarios as part of the cash flow analysis. Each class is analyzed with 43 different combinations of loss, prepayment and interest rate projections.
Classes currently rated below 'Bsf' are at-risk to default at some point in the future. As default becomes more imminent, bonds currently rated 'CCCsf' and 'CCsf' will migrate towards 'Csf' and eventually 'Dsf'.
The ratings of bonds currently rated 'Bsf' or higher will be sensitive to future mortgage borrower behavior, which historically has been strongly correlated with home price movements. The ratings of outstanding classes may be subject to revision to the extent actual home price and mortgage performance trends differ from those currently projected by Fitch.
The spreadsheet 'U.S. RMBS Alt A Rating Actions for Dec. 12, 2014' provides the contact information for the performance analyst.
Additional information is available at 'www.fitchratings.com'.
Applicable Criteria and Related Research:
--'U.S. RMBS Surveillance and Re-REMIC Criteria' (June 24, 2014);
--'Global Structured Finance Rating Criteria' (May 20, 2014);
--'U.S. RMBS Loan Loss Model Criteria' (Nov. 17, 2014);
--'U.S. RMBS Cash Flow Analysis Criteria' (April 16, 2014);
--'Criteria for Interest Rate Stresses in Structured Finance Transactions' (Jan. 23, 2014);
--'Criteria for Rating Caps and Limitations in Global Structured Finance Transactions' (May 28, 2014);
--'Counterparty Criteria for Structured Finance and Covered Bonds' (May 14, 2014);
--'Structured Finance Recovery Estimates for Distressed Securities' (Nov. 18, 2011).
Applicable Criteria and Related Research: U.S. RMBS Alt A Rating Actions
for Dec. 12, 2014