Glencore, the world’s biggest commodities trader, located about 30 kilometres outside Zurich, Switzerland, has not been a big name in the public domain, because it has been in private hands for almost 40 years. But now it represents 2011’s biggest sharemarket listing, or IPO, and in floating on the London and Hong Kong stock exchanges, Glencore has almost instantly opened itself up to all sorts of criticism. Valued at $58bn, Glencore is the world’s biggest listed trader of commodities by capitalisation – and that means it dominates the market in a way few other companies do.