Dark rumours have been swirling on the London Metal Exchange. As the price of copper has soared recently - with the spot price climbing to US$5,625 a tonne on Monday, 103 per cent above its December low - dealers have begun to whisper that there is mischief afoot.
Some believe that a shadowy but deep-pocketed investor is trying to corner the market. They recall rogue trader Yasuo Hamanaka's disastrous 1996 bid to manipulate the copper price - an attempt that ended up costing his employer Sumitomo Corp a massive US$2.6 billion - and argue something similar may be going on now.
Others suspect the mysterious buyer is loading up on copper in anticipation that a breakthrough in electric car technology will drive a surge in demand for the highly conductive metal.
Still, others detect the sinister presence of 'Voldemort'; China's State Reserve Bureau, which they believe is building massive stockpiles of strategic materials in order to diversify the mainland's vast pile of foreign exchange reserves away from a declining US dollar.
The last hypothesis, although still wide of the mark, is probably the closest to the truth.
There is no doubt that China has been buying copper heavily on world markets in recent months. As the first chart below shows, the mainland's imports of refined copper have leapt this year.