A new paper from The Australia Institute claims that the Big Four banks' common shareholdings by various nominee companies undermine their claims to independence.The study by the left-leaning think tank examines the top 20 shareholders in the banks' annual reports. It notes that just three companies - HSBC Custody Nominees, JP Morgan Nominees Australia Limited and National Nominees Pty Limited - own at least 25 per cent of each of the Big Four, and that other nominee companies also have substantial holdings.The report was given widespread publicity in News Limited newspapers yesterday."On average, over 53 per cent of each big bank is owned by shareholders that are among the top 20 shareholders in all the big banks," said the report's author, David Richardson, in a statement. "The last thing these common shareholders seem to want is genuine price competition."However, bank nominee companies are also among the major shareholders in most major Australian listed companies. It is not clear whether the report's author understands the functions of a nominee company, which is simply to hold shares on behalf of a beneficial owner.The paper also notes that the Australian banking market is both concentrated and highly profitable for the Big Four banks.