Reports emerged on Tuesday that a mystery party had a huge short position in nickel, which has doubled in price in the last six months to a record high. In the light of commodities history, these were taken seriously. In the 1970s the Hunt brothers of Texas hoovered up three quarters of the world’s privately owned silver in a disastrous attempt to manipulate prices. A decade ago rogue trader Yasuo Hamanaka was found to own most of the world’s copper inventories. A man is reportedly under house arrest in China after taking a short copper position of up to $800m last year.

Tuesday, Posco was reported to hold a 10,000-ton futures position (equating to a face value of $290m) on the London Metal Exchange. The Korean steel company has since said its position is a 10th of this size. But is there still a hidden iceberg out there? The latest LME data do indicate that there is a single big short on one of the three “snapshot” expiry days it discloses. On September 20, this party is short between 20 per cent and 30 per cent of contracts. This equates to 7,986-11,982 tonnes and a face value of $232m-347m at spot prices.