Perpetual achieved significant growth in its corporate trust division during the 2009/10 financial year but it was at the cost of margin and earnings.With the slowdown in mortgage and other asset securitisation (the mainstay of the corporate trust business) over the past couple of years, Perpetual has diversified into outsourced mortgage processing and other services.The company reported yesterday, at its financial year results presentation, that the "number of matters" in mortgage servicing increased from 96,000 to 199,000 during the year to June. Mortgage servicing revenue increased 46 per cent to $31.9 million.Securitised assets under administration fell from $241 billion to $210 billion during the year and revenue from trust and fund services fell five per cent to $55.6 million.The change in the corporate trust business mix has hit its margin. The division's margin on revenue fell from 45 to 37 per cent and pre-tax profit fell from $36.1 million to $32.3 million.Perpetual chief executive David Deverall said costs had increased as the division focused on business acquisition. The focus in the current year will be improved profitability.Deverall said a positive sign for the business was the gradual increase in the RMBS deal pipeline this year.The corporate trust division contributed 24 per cent of Perpetual's pre-tax earnings. The group reported net profit of $90.5 million, a big improvement on the 2008/09 net profit of $37.7 million.