The US Federal Reserve plans to require non-US banks to house their US businesses in regulated holding companies which are subject to US bank capital requirements.The move, flagged in a speech overnight by Fed board member Daniel Tarullo, will force foreign banks in the US to either expand their capital base or shrink their assets.It is not yet clear what impact the new rules will have on Australian banks operating in the US.The announcement has been widely seen as aimed at banks such as Deutsche Bank and Barclays Plc which have discarded their holding-company structure in the past two years in an attempt to keep capital requirements low.