In this article, Andrew Bowen examines so-called 'Ponzi' schemes, investment frauds in which investors are lured by the prospect of high returns but these returns and the trades on which they are based are fictitious. He looks specifically at the case of So v HSBC Bank Plc [2009] where the Court of Appeal considered claims by investors that the bank owed a duty of care to those investors when they were not customers and whether the bank's breach of duty had been the effective cause of the loss. This article originally appeared in Issue 101 of W. Greens Business Law Bulletin and is reproduced here with their kind permission.