OREANDA-NEWS. November 30, 2015. Fitch Ratings has affirmed the ratings of four tranches of Series 2015-1 WST Trust and Series 2014-2 WST Trust. The issuance consists of notes backed by first-ranking Australian residential mortgages, originated by Westpac Banking Corporation (WBC; AA-/Stable/F1+). The ratings are as follows:

Series 2015-1 WST Trust
AUD1,651.4m Class A notes: 'AAAsf'; Outlook Stable
AUD71.5m Class B notes: 'AAAsf'; Outlook Stable

Series 2014-2 WST Trust
AUD1,872.8m Class A notes: 'AAAsf'; Outlook Stable
AUD92.0m Class B notes: 'AAAsf'; Outlook Stable

KEY RATING DRIVERS
The affirmations reflect Fitch's view that available credit enhancement is sufficient to support the notes' current ratings, our expectations of Australia's economic conditions, and the fact that the credit quality and performance of the loans in the collateral pool have remained in line with expectations.

The default model was not run for this rating action as the outstanding ratings are 'AAAsf' and a review of pre-determined performance triggers indicates that the transactions display stable asset performance.

At November 2015, 30+ day arrears were low at 0.36% and 0.26% for Series 2014-2 WST Trust and Series 2015-1 WST Trust respectively, compared to Fitch's Dinkum RMBS Index of 1.12%. The weighted average loan/value ratios for Series 2014-2 WST Trust and Series 2015-1 WST Trust are 60.55% and 61.34%, respectively. As of November 2015 neither transaction had experienced a loss.

RATING SENSITIVITIES
Sequential pay-down has increased credit enhancement for the senior notes of each transaction, with the 'AAAsf' rated notes able to withstand many multiples of the latest reported arrears. The ratings are not expected to be affected due to any foreseeable change in performance. The rated notes are independent of downgrades to the lender's mortgage insurance providers' ratings.

DUE DILIGENCE USAGE
No third party due diligence was provided or reviewed in relation to this rating action.

DATA ADEQUACY
Fitch conducted a file review of 10 sample loan files focusing on the underwriting procedures conducted by Westpac Banking Corporation compared to its credit policy at the time of underwriting. Fitch has checked the consistency and plausibility of the information and no material discrepancies were noted that would impact Fitch's rating analysis.

A comparison of the transaction's representations, warranties and enforcement mechanisms (RW&Es) to those of typical RW&Es for this asset class is available by accessing the reports and/or links under Related Research below.