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

Oct. 26

Weekly Loss

My Watchlist

Overseas Shipholding (NYSE:OSG)

$1.23

(62%)

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Tempur-Pedic (NYSE:TPX)

$25.40

(23%)

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Crocs (NASDAQ:CROX)

$12.73

(22%)

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iRobot (NASDAQ:IRBT)

$17.99

(22%)

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Cliffs Natural Resources (NYSE:CLF)

$36.49

(18%)

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Source: Barron's.

Overseas Shipholding was the market's biggest loser, shedding nearly two-thirds of its value after revealing that it's considering strategic alternatives including the possibility of filing for bankruptcy reorganization. Naturally, Moody's and S&P downgraded the company's credit rating after that.

Tempur-Pedic was as lumpy as the mattresses it seeks to replace. The premium bedding maker posted another disappointing quarter, slashing its top- and bottom-line guidance for the entire year.

Shares of Crocs slipped after the maker of resin footwear missed Wall Street's sales targets. Weakness in once-strong overseas markets also finds Crocs hosing down its projections for the balance of the year.

iRobot is malfunctioning. The maker of home and defense robotics posted better-than-expected results for its most recent quarter. iRobot has been very good on that front. However, weak defense spending is forcing the company to forecast near-term weakness in its business.

Finally we have Cliffs Natural Resources. It isn't easy to be a miner when the commodity that you are extracting -- in this case, seaborne iron ore -- sees its average selling price fall by more than a third over the past year. The result is that Cliffs margins are getting crushed.