New Suncorp chief executive Steve Johnston believes the bank's net interest margin will stabilize this year as the benefits of recent deposit repricings take effect.In a strategy presentation to the annual UBS Australasia Conference in Sydney on Monday, Johnston revealed the company's bank was unlikely to suffer further margin erosion in 2020."The bank has continued to experience strong growth in at-call deposits, particularly in October, with the majority of this growth coming through digital channels," he told the conference. "This strong growth in deposits combined with the falling BBSW will have a positive impact on NIM which is expected to be consistent with the second half of 2019 at around 1.90 per cent."Suncorp's reported net interest margin declined by five basis points to 1.79 per cent in the 12 months to the end of June using a calculation method that the company has since discarded.Under a new formula adopted from 1 July, the bank's reported NIM would have been in the range of 1.85 per cent to 1.95 per cent.Stabilisation of the interest margin would be a positive for the bank as it tries to arrest sharp declines in lending volumes.According to its latest quarterly update, Suncorp continued to lose ground in the home loan market in the three months to the end of September after the bank's mortgage book tapered by A$303 million.The contraction equated to a 0.6 per cent decline in the home loan business, which extended a negative trend that became apparent 12 months ago.The Brisbane-based regional also struggled in personal lending, with the value of its book sliding more than 11 per cent to $150 million since the end of September last year.In an outlook statement contained in its quarterly report, the bank did not forecast when it expected mortgage activity to recover."While property markets are showing signs of recovery due to lower interest rates, strong competition for good quality owner occupier and investor business is expected to continue, with lower rates continuing to put further pressure on home loan refinancing volumes," the company said.Chief financial officer Erin Strang said there had been a recovery in lodgement volumes since July but that heavy refinancing activity would exert pressure on the business in 2020."We have focused on driving growth through our direct and broker partner channels, as well as improving our digital settlement capabilities and retention initiatives," she said."As a result of these initiatives we have seen a steady increase in lodgement volumes and improved turnaround times over the quarter, and this will continue to be a focus throughout the year."We expect there will be ongoing competitive pressure for home loan refinancing options during the second half of the 2020 financial year." Johnston said the bank was mostly focused on growing volumes in the Queensland market by improving broker response times."Momentum in lodgement volumes has been improving since July and service levels are now back within targeted turnaround times," he told the conference."Winning in our home market and continuing to improve broker service levels is critical to