Margin contraction, credit card losses and a blowout in technology costs have crunched ME Bank's bottom line earnings for the 12 months to the end of June 2019.The bank, which is owned by Australian Super, HESTA and 24 other industry super funds, suffered a 25 per cent slide in full year profit to A$67.1 million despite recording strong growth in its core deposits and mortgage operations.The profit dive means ME's owners achieved a return on equity of around 7.2 per cent last year - down from the 8 per cent plus returns posted since 2016.While chief executive Jamie McPhee acknowledged that a string of non-recurring costs had taken a toll on the bottom line, he insisted that momentum in the business remained solid throughout the 12 month period."Despite experiencing one of the toughest years in banking, with record low credit growth, record low interest rates, a highly competitive environment and increased regulation, ME has grown strongly in both home loans and household deposits and has increased its market share and customer base," he said."The underlying growth of the business is strong."Profitless growth in home lending has emerged as a key theme of the 2019 reporting season, with a swathe of  small banks and credit unions expanding market share in home lending for little or lower returns.While ME grew its home loan book  by 7.7 per cent  - a rate that eclipsed the major banks and lending peers such as Bendigo Bank and Bank of Queensland - its interest revenue was crimped by a 3 basis point decline in the net interest margin to 1.59 per cent.McPhee indicated that the margin pressure forced the bank to review its deposit marketing strategy in the middle of the year, which led to a decision to rein in aggressive pricing on some deposit products.Data published by APRA shows that deposit growth at the bank slowed in the six months to June."We experienced really strong growth in the first half of the year and we wanted to balance that with margin management in the second half," he said.However there were other big drags on ME's result in the form of one-off costs and write downs in the credit cards business and the digital transformation program.Impairment losses in the credit card portfolio wiped more than $14 million from operating earnings and IT costs relating to the decommissioning of the ULTRACS core banking system blotted another $15 million.McPhee said the transformation program, which has seen the bank migrate to a Temenos 24 core platform, was expected to be completed by the end of the current year."About 87 per cent of the bank's business is now operating on the new system," he said."We are now migrating our personal loans business to the new platform."ME often attracts criticism in social media chatrooms for having a high frequency of system outages.However, data published by the Down Detector website (downdetector.com.au) indicates that outage frequency has more than halved in the last two years since the bank migrated most of its operations