Heritage Building Society made a return to the mortgage-backed securities market after a five-year absence, when it priced a mortgage-backed bond yesterday.Heritage will pay 110 basis points over the one-month bank bill swap rate for the A$749.6 million class A tranche of HBS Trust 2011-1.The weighted average life of the tranche, at 2.8 years, is in line with recent issues by Citibank and AMP, but shorter than the three years-plus achieved by ING Direct.The $21.6 million of class AB notes, which have a weighted average life of 5.5 years, were priced at 195 basis points over swap.The Australian Office of Financial Management took up the whole of the AB tranche.Pricing on the $28.8 million class B tranche was not disclosed.The deal was upsized to $800 million from the $500 million announced when the deal was launched last week. It is Heritage's biggest domestic transaction.Heritage said there were 16 investors. The majority were balance-sheet investors and there were no offshore investors.