With a one per cent share of the home loan market, mortgage growth in the order of 20 per cent and a cost to income ratio unmatched in the industry, AMP Limited continues to look to its banking arm for superior returns.One aim, the insurance group set out yesterday, is to "double the value of the bank by 2021, via earnings and dividends."Operating profit for the bank lifted ten per cent over the half year to June 2017 to A$65 million. With APRA's stiffer capital targets in mind, the return on equity fell to 16.3 per cent from 17.2 per cent a year ago.The cost to income ratio for the bank remains in the order of 29 per cent.The bank, now led by Sally Bruce, a group executive at AMP, is also producing exceptional growth in household deposits, up 16 per cent in one year.The strategy for the bank fits in with wider group themes, set out by AMP CEO Craig Mellor as "tilting investment to higher growth businesses ... less capital intensive businesses."AMP Bank "continues to grow strongly and represents a significant opportunity for AMP by integrating debt and cashflow management strategies," Mellor said.