There is a speculative element to the rise in metal prices, too. Buying or selling copper futures is a popular way to express a view about the world economy. Indeed copper can be all about belief, says Max Layton of Citigroup, a bank. Many of the bets laid on it are by trading algorithms, which mechanically respond to financial signals that have worked well in the past. The dollar, which has fallen by 6% against a basket of currencies since March, is usually part of the semaphore. A weaker dollar allows for easier terms of finance in emerging markets. Anything that helps emerging-market economies is generally good for commodity prices. So the algorithms buy.
A pattern in markets is that a lot happens by rote. China’s response to a weak economy is to build; investors’ response to the Fed’s easing is to buy stocks; the algorithms’ response to a weaker dollar is to buy commodities. Higher prices beget higher prices. The sceptics, the too-sooners, note that this also works in reverse. Quite so. But the momentum is now with the believers.
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