Mortgage finance company FirstMac will pay 150 basis points over the bank bill swap rate for an AAA-rated tranche of mortgage securities with a weighted average life of 2.9 years.This represents a significant widening of margins compared with the pricing of similar tranches in other recent deals. In late November, Suncorp paid 135 basis points over swap for an AAA-rated tranche with a weighted average life of 2.27 years. In early November, ING Direct also paid 135 basis points over swap for an AA-rated tranche with a weighted average life of 2.7 years.FirstMac raised a total of A$300 million through the issue of 2-2011 Residential Mortgage-Backed Securities.It will pay 65 basis points over swap for the $75 million A1 tranche, which has a weighted average life of six months.Pricing on the $114.8 million A2 tranche, with a weighted average life of 2.9 years, is 150 basis points over swap.Pricing on the $87.7 million A3 tranche, with a weighted average life of seven years, is 165 basis points over swap. The AB tranche, worth 11.7 million, is priced at 275 basis points over swap.The Australian Office of Financial Management invested $87.7 million in the A3 notes and $11.7 million in the AB notes.