More big names have joined the list of banks threatened by an alleged fraud in the United States. Spain’s Santander admitted its exposure could reach 2,3 billion euros, while HSBC feared losses of a billion. France’s Natixis put the figure at around half a billion.70-year-old Bernard Madoff, once chairman of the hi-tech Nasdaq stock exchange, is accused of masterminding a 40 billion euro pyramid fraud through his investment advisory business. He is under arrest, with American financial regulators blamed for failing to scrutinise his affairs, and being blinded by his Wall St reputation. The pyramid scheme is said to have promised investors high returns on their money, while in reality only those whoe jumped in early were paid by funds collected from later investors. Because such schemes depend on a constant flow of new money they eventually collapse under their own weight, leaving investors out of pocket.