Copper is just one of the commodities that has shown major weakness this week, and today it fell to the lowest level since October 2011.
Some worry that this could be bad news for the stock market. After all, the metal is sometimes called "Dr.Copper," because it is thought to check up on the market's health.
The checkup is not going so well.
Do you think copper is delivering a warning about stocks, or should investors not sweat it?
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