HSBC Bank Australia suffered a big fall in earnings in the June half, as a result of a steep rise in loan impairments.HSBC Holdings plc released its interim results yesterday, in which it reported that pre-tax profit for the Australian business fell from US$206 million in the six months to December to US$132 million in the latest half.The fall was due, in part, to an increase in "individually assessed charges, primarily driven by a small number of charges related to metals and mining exposures."Pre-tax profit for the global banking and markets division fell from US$128 million to US$59 million half on half.Commercial banking also suffered a big fall, with pre-tax profit down from US$61 million in the December half to US$25 million in the latest half.Retail banking and wealth management was the star performer. The division's pre-tax profit rose from US$24 million in the December half to US$50 million in the June half.