Commonwealth Bank completed the biggest-ever Australian dollar mortgage securitisation on Wednesday, when it priced the A$3 billion Medallion Trust Series 2011-1.The $2.25 billion class A1 notes, which have a weighted average life of 2.2 years, were priced at 95 basis points over the one-month bank bill swap rate.In other RMBS news, Community CPS yesterday priced its inaugural mortgage securitisation, the $300 million Barton Series 2011-1. The $195 million class A1 tranche, with a weighted average life of 1.6 years, was priced at 95 basis points over the one-month bank bill swap rate. The pricing of these deals provides further evidence of the tightening of spreads that has been underway since the second half of last year. Spreads on A1 tranches have come in from around 120 basis points over swap during the past six months.Commonwealth Bank's head of group funding, Simon Maidment, said: "We are very happy with the pricing and the volume."The pricing is in line with the domestic senior unsecured market, and more competitive than some offshore opportunities."The Medallion issue was upsized from $1 billion. Commonwealth issued $7 billion of Medallion notes in 2007, but a lot of that deal was in euros and US dollars.It was Medallion's first issue since 2007, although Commonwealth's subsidiary, Bankwest, completed two Swan Trust RMBS issues last year, in April and October, paying between 120 and 130 basis points over swap for the A1 tranches."The price and volume potential of the market is very good," said Maidment.Pricing on the $525 million class A2 tranche was 6.5 per cent, fixed for five years. CBA used a "soft bullet" structure for the tranche, which means that no principal is repaid on the notes prior to the A2 refinancing date, in April 2016. The A2 notes are eligible for inclusion in the UBS composite bond index and were designed to appeal to fixed interest investors. Pricing on the $108 million of AB notes was 170 basis points over swap, and pricing on the AC notes was 205 points over.Maidment said there were 35 investors in the deal - two-thirds of them real money investors. "That is very encouraging. We were hoping for a 50/50 split or 70/30 the other way."The Australian Office of Financial Management purchased the class A2 tranche of the Community CPS deal, which has a weighted average life of 6.5 years and was priced at 125 basis points over swap. Pricing on the $7.8 million class AB tranche was 195 basis points over swap.