A global super-rich elite has exploited gaps in cross-border tax rules to hide an extraordinary US$21 trillion ($26 trillion) of wealth offshore - as much as US and Japanese GDPs put together - according to research commissioned by the campaign group Tax Justice Network.
James Henry, former chief economist at consultancy McKinsey and an expert on tax havens, has compiled the most detailed estimates yet of the size of the offshore economy in a new report, the Price of Offshore Revisited.
He shows that at least US$21 trillion - perhaps up to US$32 trillion - has leached out of scores of countries into secretive jurisdictions such as Switzerland and the Cayman Islands with the help of private banks, which vie to attract the assets of so-called high net worth individuals.
Their wealth is, as Henry puts it, "protected by a highly paid, industrious bevy of professional enablers in the private banking, legal, accounting and investment industries taking advantage of the increasingly borderless, frictionless global economy".
According to Henry's research, the top 10 private banks, which include UBS and Credit Suisse in Switzerland, as well as the US investment bank Goldman Sachs, managed more than US$6 trillion in 2010, a sharp rise from US$2.3 trillion five years earlier.