Speculators quadrupled their net bet on higher copper prices in the week ended Tuesday, the CFTC says, evidently undeterred by worries about credit-market turmoil in the top consumer of the metal. China has given investors some upbeat data on broad-based growth and industrial activity the last few weeks. Copper stockpiles outside of China continue to slide, down 30% from the decade high earlier this year, and the prevailing view is this metal is flowing into Chinese warehouses. Meanwhile, analysts say copper intensive-power infrastructure construction continues to roar along. That’s helped prices defy gravity a bit the last few months: Comex copper gains 0.9% this week $3.2985.