MELBOURNE (S&P Global Ratings) May 30, 2018--S&P Global Ratings today assigned its preliminary ratings to four classes of prime residential mortgage-backed securities (RMBS) to be issued by Perpetual Trustee Co. Ltd. as trustee for Progress 2018-1 Trust (see list). Progress 2018-1 Trust is a securitization of prime residential mortgages originated by AMP Bank Ltd. The preliminary ratings reflect: Our view of the credit risk of the underlying collateral portfolio, including the fact that this is a closed portfolio, which means no further loans will be assigned to the trust after the closing date. Our view that the credit support is sufficient to withstand the stresses we apply. This credit support comprises note subordination and lenders' mortgage insurance policies. The benefit