Perpetual's corporate trust division, which does the bulk of the trustee work in the residential mortgage-backed securities and covered bond markets, benefited from a 50 per cent increase in RMBS issuance in the 2012/13 financial year.Yesterday, Perpetual reported that its corporate trust division had increased net profits by five per cent in the year to June - up from A$17.4 million, in 2011/12, to $18.3 million.Securitisation assets grew by $42.4 billion - up 20 per cent on the previous year.The division acquired 18 new trust services' clients and 14 new fund services' clients.The division's results have been affected by restructuring. In February it sold its loan servicing business, with contracts worth $1.3 billion, and last year it sold a mortgage processing business, PLMS.The revenue contribution from these businesses fell from $2.7 million, in 2011/12, to $1.3 million in the year to June.The company's strategy is to get out of low margin work and focus on more profitable business.The pre-tax margin on revenue rose from 33 per cent, in 2011/12, to 37 per cent in the year to June.Perpetual is in the middle of a prolonged battle with Equity Trustees to acquire The Trust Company. If Perpetual is successful, the acquisition will add substantially to its corporate trustee business.