National Australia Bank has lifted its share of the mortgage market by more than two percentage points since the nadir in its market share in 2010 - a dip that helped spur the repositioning of the bank's products and services in early 2011 (the so-called "break up" strategy).Data compiled by the Australian Prudential Regulation Authority up to the end of December 2012 shows NAB's market share of home loans was 16.4 per cent. The bank's market share stood at around 14.2 per cent in May 2010.Banks that lost market share in home loans over the calendar year 2012, based on APRA data, include Commonwealth Bank, down 0.8 percentage points to 27.2 per cent, and Westpac, down half a percentage point to 25.6 per cent.NAB also lifted its share of household deposits, to 14.9 per cent, at the end of last year - a rise in market share of 1.5 percentage points.The tussle for market share in lending continues in a market segment growing at an unusually slow rate.Monthly financial aggregates released by the Reserve Bank of Australia yesterday put growth in home lending at 0.3 per cent in December 2012, with year-end growth of 4.5 per cent. This is a third of the rate of growth six years ago.The RBA put overall credit growth at 3.6 per cent for the year to December.