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 FXCM (Nasdaq: FXCM), a foreign exchange broker, fell more than 14% after reporting lower trading volume in January. A Citigroup analyst also downgraded the stock from buy to hold, Barron's reports.

So what: Retail foreign exchange transactions increased 11% from December but fell 7% year over year, to 307,689 trades.

Now what: With today's decline, shares of FXCM are down more than 20% since its December IPO. Should investors care? I'm not so sure. A global economy is going to need smooth forex services to grease the skids of trade, but analysts have yet to figure out how that will translate into growth for FXCM's business.

I can't blame them for failing to go on record. FXCM's revenue soared 73% in 2008 but flatlined the next year. Profits quintupled in 2008 only to fall 24% in 2009. Zig, meet zag. Avoid this stock until there's evidence of a growth pattern forming.

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Fool contributor Tim Beyers is a member of the Motley Fool Rule Breakers stock-picking team. He didn't own shares in any of the companies mentioned in this article at the time of publication. Check out Tim's portfolio holdings and Foolish writings, or connect with him on Twitter as @milehighfool. You can also get his insights delivered directly to your RSS reader. 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 is also on Twitter as @TheMotleyFool. Its disclosure policy is at least 10% better than other disclosure policies.