China imposes fresh curbs on commodities as iron ore, steel slide

By Ruby Lian and Manolo Serapio Jr BEIJING/MANILA (Reuters) - Chinese commodities exchanges stepped up efforts on Tuesday to curb surging prices that some say have been driven by speculators, raising fears of another derivatives bubble after last year's stock market collapse. Transaction fees for iron ore futures were hiked for a second time in as many days, after the original increase led to a sharp drop in iron ore and steel futures in China that helped cool a week-long surge in local commodit