Margins of 90 or 95 basis points over the bank bill swap rate that issuers of residential mortgage-backed securities were paying in the first half of the year appear to be out of reach now.A week after ING Direct paid 100 basis points on the top tranche of the IDOL Trust Series 2013-2 (compared with the 95 bps it paid in March), AMP Bank has priced the top tranche of its latest deal at 100 bps over the one-month bank bill swap rate.AMP Bank's Progress 2013-1 Trust issue was finalised yesterday, with the deal being upsized from the A$500 million offered at the launch to $650 million.Pricing on the $598 million A tranche, which has a weighted average life of 3.6 years, is 100 bps over the one-month bank bill swap rate.Pricing on the $39 million AB tranche, which has a weighted average life of six years, is 190 bps over the swap rate.Pricing on the $9.75 million B1 tranche, which has a weighted average life of six years, is 290 bps over swap.And pricing on the $3.25 million B2 tranche, which has a weighted average life of six years, is 350 bps over swap.AMP Bank said 22 investors had bought the notes. Deutsche Bank was the arranger of the transaction. Deutsche Bank, Commonwealth Bank, National Australia Bank and Westpac were joint lead managers.