Ken Henry, chair of the board of National Australia Bank, yesterday produced the biggest clanger yet at hearings of the banking royal commission - unaware or forgetting the bank's punishment one year ago for rate rigging around the bank bill swap rate from 2010 to 2012.Drawn by counsel assisting, Rowena Orr to meditate on "financial institutions all over the world continuing to engage in serious misconduct", and specifically prompted on "the manipulation of interbank interest rates and foreign exchange rates," Henry recalled little of his brief."So far as I know, nobody has yet established that there has been any manipulation of those rates in Australia," the NAB chair of three years said.Last year NAB volunteered that it made attempts on each of 20 December 2010, 17 January 2011, 7 February 2011, 7 February 2011, 30 June 2011, 12 July 2011, 5 October 2011 and 25 October 2011 "to engage in conduct [in the prime bank bill market], in trade or commerce, in connection with the supply or acquisition of financial services that was, in all the circumstances, unconscionable."In a ruling in November 2017, Justice Jayne Jagot wrote that NAB "agreed that the attempted contraventions were deliberate and not transparent to counterparties." The bank paid a penalty of A$10 million, the same as imposed on ANZ for similar conduct. The Federal Court has also sanctioned Westpac and two other banks for manipulating BBSW. Dodgy conduct in the realm of foreign exchange has also been established, admitted by NAB this time two years ago. This was a chief topic of Friday's hearings, or more specifically NAB's inability to fully remedy illegal conduct in the FX market.In December 2016 ASIC entered into enforceable undertakings with both NAB and Commonwealth Bank "in relation to the banks' wholesale spot foreign exchange (FX) businesses".The regulator said that, as a result of its investigation, it was "concerned that between 1 January 2008 and 30 June 2013, both banks failed to ensure that their systems and controls were adequate to address risks relating to instances of inappropriate conduct identified by ASIC."