Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of aluminum producer Noranda Aluminum (NYSE: NOR) are down by nearly 14% today as of this writing. Analysts downgraded three stocks in the sector -- including Noranda -- because of macroeconomic concerns.

So what: Fellow aluminum companies Alcoa (NYSE: AA) and Century Aluminum (Nasdaq: CENX) were among the group that were downgraded and were also seeing heavy selling pressure. Deutsche Bank downgraded Alcoa from buy to hold, while Morgan Stanley downgraded Century Aluminum from overweight to equal-weight and Noranda Aluminum from equal-weight to underweight.

Now what: The analysts cited greater risks because of softness in the global economy and heightened risk aversion because of the European debt crisis, which may weigh on the demand for industrial metals like aluminum. The analysts believe gold miners are a better play in metals than aluminum. Alcoa was cited as stronger than the other two since it is somewhat "insulated from metals prices" compared to the others and the company's performance reflects broader economic trends.

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Fool contributor Evan Niu holds no position in any company mentioned. Click here to see his holdings and a short bio. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.