The Bloomberg Commodity Index has tumbled about 10 percent from a high in May amid mounting concerns that a trade war could derail global growth, curbing demand for everything from aluminum to soybeans. This week BNP Paribas cut its gold forecast for this year to $1,250 and $1,100 for 2019. Harry Tchilinguirian, head of commodity research at BNP Paribas, talks with Bloomberg's Alix Steel about the reasons behind the change in the forecast. (Source: Bloomberg)