Mutual banks are jostling for bragging rights in industry growth stakes in Australian lending, with four large names putting a degree of substance into the mutual ADI sector's pretence to being a fifth pillar in banking.Defence Bank, Bank Australia, Police & Nurses and Teachers Mutual Bank - spanning the country's four largest regional markets - have enjoyed growth in mortgage funding over the two years to June 2016 matching or bettering twice the industry growth rate of 13.8 per cent over this period.Of the big banks, only ANZ pursued market share growth over this period, in contrast to a NAB somehow steering its two-year growth rate to 8.2 per cent, less than two thirds of system at an institution once proud of taking market share from leaders.In housing lending in Australia, Commonwealth Bank and Westpac remain the leaders, their combined market share of 52.17 per cent rationed to favour CBA, on 27.07 per cent, and Westpac on 25.1 per cent.Commonwealth Bank's market share number is usually pretty sturdy in the lead up to a half year result (with one due next Wednesday).In 2016 CBA's market share, having flagged over two years, is now swimming along at 1.3 times system over the last six months, NAB the major bank dropping market share at 0.7 times system.Windows of opportunity for market share growth have well and truly been taken by the quartet of mutual banks listed above.Bank Australia (formerly bankmecu) leads not just mutual banks but all banks on home loan growth over two years to June 2016. Bank Australia reported mortgage growth of 33.6 per cent over this period.Police & Nurses, from Perth, ranked second at two-year growth of 30.3 per cent.Teachers Mutual Bank, from Sydney, ranked third with 29.8 per cent growth.A mutual kicking along at just under twice system was Defence Bank, a Brisbane outfit and one of two former credit unions dependent on the armed services for growth, in their case 26.7 per cent.