Banks' mortgage balances grew at more than twice the rate of growth in household deposits in May, as lenders shrugged off concerns about their stable funding ratios and chased market share in the improving home loan market.According to the latest Australian Prudential Regulation Authority banking statistics, household deposit balances grew by 0.3 per cent in May, while mortgage balances were up 0.7 per cent.Over the three months to May, household deposit balances grew by 1.6 per cent, while mortgage balances grew by 1.8 per cent.Banks whose deposit balances grew ahead of system in May include ANZ, ING Direct, Macquarie Bank, ME Bank, RaboDirect and Westpac.Commonwealth Bank and National Australia Bank were below system and Bank of Queensland, Bendigo and Adelaide Bank, Citibank suffered net outflows.On the lending side, Macquarie Bank continues to shoot the lights out, with 3.1 per cent in its mortgage book in May and 8.5 per cent growth over the three months to March.Other lenders with growth at system or above in May include ANZ, HSBC and NAB.