The former head of mining company Xstrata has backed a new industrial commodity-focused hedge fund. Mick Davis, who left Xstrata in 2013 after more than a decade at the firm, was one of the early investors in Commodity Asset Management, the $10-million fund started by former AQR Capital Management trader Nathaniel Polachek and Jonathan Tulkoff, a physical commodity trader, according to a person familiar with the matter.