The dollar's five-day rally and China growth concerns are making for an ugly day in commodities and commodity stocks.
Iron ore and rebar (reinforced steel) both traded limit down (6 percent) in trading on China's Dalian Commodity Exchange and the Shanghai Futures Exchange, respectively.
Weak trade data was the primary problem, but there are other issues as well.
It's another example of Chinese authorities allowing, and then reigning in, speculative activity. Commodity prices rose in the last month on some signs that China's economy may be stabilizing, leading to a surge in speculative activity on China's commodities futures exchanges.
This alarmed Chinese regulators, who have announced they are conducting investigations and may even raise transaction fees to curb speculation.
Naturally, this has led to speculation that China's economic trend is down, not up, so commodities are down notably today: iron ore down 6.2 percent, copper down 2.3 percent, aluminum down 2.4 percent.