Sydney-based hedge fund Tribeca Global Natural Resources has called for an overhaul of the BHP Billiton board, which it claims has wasted $US30 billion ($40 billion) of capital, a figure that could have been $US50 billion ($67 billion) higher if not for deals it failed to get done. Tribeca, the world's top performing hedge fund of 2016, said the miner had "a critical opportunity to reset the culture" with the retirement of long-serving chairman Jac Nasser and said that improvements can only be made with "significant turnover" of the board. Tribeca outlined its concerns in an eight-page letter titled "Making...