There's never a shortage of losers in the stock market.

Let's take a closer look at five of this past week's biggest sinkers.

Company

Aug. 10 Weekly Loss My Watchlist
Ubiquiti Networks (Nasdaq: UBNT) $8.71 (30%) Add
Roundy's (Nasdaq: RNDY) $7.71 (21%) Add
Exelixis (Nasdaq: EXEL) $4.46 (20%) Add
Achillion Pharmaceuticals (Nasdaq: ACHN) $5.61 (17%) Add
priceline.com (Nasdaq: PCLN) $563.16 (15%) Add

Source: Barron's.

Ubiquiti Networks tumbled after the company issued guidance calling for a shocking sequential decline in revenue and profitability. Terminated distributors have apparently created a model-stinging market of counterfeit versions of Ubiquiti's AirMax product.

Grocery stores have had it rough this earnings season, and the recently public Roundy's is no different. Shares of the supermarket chain tumbled after the company posted disappointing quarterly results. The silver lining here is that Roundy's is committed to maintaining its meaty dividend rate, resulting in a yield that got even fatter after the stock's drop.

Exelixis took a hit after issuing secondary stock and convertible debt offerings. Investors don't like to see their stakes in the drugmaker diluted that way, even if it means that Exelixis is raising money.

Achillion Pharmaceuticals put out encouraging news for its hepatitis C treatment, but a disappointing quarter and concerns about the treatment itself held the stock back.

Even though Priceline managed to once again beat Wall Street's profit target, investors were unimpressed by the online travel portal's uninspiring guidance. Weakness in Europe -- a strong market for the company's Booking.com website -- is weighing on its growth potential.

Ready for a bounce
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The Motley Fool owns shares of priceline.com and Exelixis. Motley Fool newsletter services have recommended buying shares of Exelixis and priceline.com. The Motley Fool has a disclosure policy. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. Try any of our Foolish newsletter services free for 30 days.

Longtime Fool contributor Rick Munarriz calls them as he sees them. He does not own shares in any of the stocks in this story. Rick is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early.