AMP is aiming for "double digit earnings growth" from AMP Bank over the medium term, AMP Group declared yesterday.In a long-awaited strategy update, Francesco De Ferrari, chief executive of AMP, said the group intended to "further integrate banking solutions with wealth management to increase client engagement" as a pillar of "reinventing the Australian wealth management business to capitalise on industry disruption."Over AMP's first half of 2019, the bank's earnings stood up thanks to  a "resilient" net interest margin - in the face of a credit ratings downgrade. AMP's credit rating was downgraded by S&P in early March 2019 from A to A- and all ratings were placed on CreditWatch with negative outlook at the time.AMP Bank reported a net profit for the June 2019 half year of A$71 million, level with the December 2018 half year but down nine per cent on the same period last year.At 1.70 per cent the bank's margin in unchanged from the 2018 full year.In the short term AMP Bank "continues to target total lending growth at or above system, subject to risk appetite, regulatory landscape, return on capital hurdles and funding availability".One segment of the bank's credit book - the practice finance loan portfolio - is now severely impaired as a consequence of the strategic decision of the AMP Group board to drastically reduce the earnings multiple at which AMP will act as "buyer of last resort" to purchase the servicing rights attached to AMP's client registers.An intragroup indemnity is in place covering any credit losses that relate to practice finance loans, and "accordingly, AMP Bank does not report impairment charges for these loans".