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

Nov. 23

Weekly Loss

My Watchlist

K12 (NYSE:LRN)

$16.27

20%

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Best Buy (NYSE:BBY)

$11.70

15%

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Scholastic (NASDAQ:SCHL)

$26.39

15%

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Cliffs Natural Resources (NYSE:CLF)

$31.23

12%

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Diamond Foods (NASDAQ:DMND)

$13.28

12%

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Source: Barron's.

K12 got schooled after a Wells Fargo analyst's downgrade. The firm cooled on the Web-based education provider after problems with its Colorado Virtual Academy charter. It's been a rough time for investors in for-profit educators. Most of the attention has been given to the post-secondary players with virtual college programs, but K12 shows that you can still flunk out at the grade-school level.

Best Buy was unplugged after another disappointing quarterly report. The consumer-electronics retailer saw its shares fall to its lowest levels since the turn of the millennium. Sluggish same-store sales and a tiny adjusted profit don't make for the kind of momentum that Best Buy needs heading into the critical holiday shopping season.

Scholastic earned a dunce cap after the publisher of kid-friendly books hacked away at its outlook. For its fiscal year ending in May, Scholastic now sees a profit of no more than $1.60 a share. Its previous guidance was calling for earnings per share to clock in between $2.20 and $2.40.

Cliffs Natural Resources stumbled after revealing that it plans to shut down some stateside production and delay an expansion at a Canadian iron ore mine.

Diamond Foods was also cracked open after an analyst downgrade. Jefferies & Co. talked down the company's prospects given the lack of earnings visibility. The analyst's new price target of $10 is well below where the stock sits now.

Longtime Fool contributor Rick Aristotle Munarriz has no positions in the stocks mentioned above. The Motley Fool owns shares of Best Buy and Wells Fargo. Motley Fool newsletter services recommend Best Buy, K12, and Wells Fargo. Try any of our Foolish newsletter services free for 30 days. We Fools don't 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.