BOSTON (TheStreet) -- The S&P 500 Index has fallen 4% this year after posting a monumental rebound in 2009. Individual members of the benchmark index have suffered more pronounced downturns. And many of the laggards are closely watched companies.

Here are the 10 worst-performing S&P 500 stocks of 2010. They are ordered by return, from bad to worst.

10. Monster Worldwide ( MWW), a global online job site, has tumbled 32% this year. Monster's first-quarter loss more than doubled to $24 million, or 20 cents a share, as revenue declined 15%. The operating margin fell further into negative territory. Despite improved bookings and the steady ascent of its proprietary Employment Index, Monster has been punished by market participants. Its stock is conspicuously expensive, trading at a price-to-projected-earnings ratio of 40, a 75% premium to the Internet services industry average.

9. Diamond Offshore Drilling ( DO), a contract oil-and-gas driller, has decreased 34% in 2010. An offshore drilling moratorium and fears of legislative repercussions for the BP ( BP) Gulf spill have hurt sentiment on Diamond. First-quarter profit fell 17%, to $291 million, or $2.09 a share, as revenue declined 2.9%. Pessimism has created a discount. Diamond sells for a price-to-projected-earnings ratio of 8.5 and a price-to-cash-flow ratio of 5.8 -- 62% and 44% discounts to peer averages. Analysts are lukewarm on Diamond, with just 21% rating its stock "buy."

8. Aluminum specialist Alcoa ( AA) has fallen 34% this year. The metals company has posted losses in five of the past six quarters despite ongoing efforts to streamline operations. Its first-quarter loss narrowed 60%, to $201 million, or 19 cents a share, as revenue advanced 18%. Alcoa is the worst-performing Dow Jones Industrial Average component of 2010. Its shares sell for a price-to-projected-earnings ratio of 9.8, a price-to-book ratio of 0.9 and a price-to-sales ratio of 0.6, discounts of 46%, 70% and 91% to respective materials peer averages.

7. King Pharmaceuticals ( KG) sells branded drugs for humans and animals. Its stock has dropped 35% this year. King acquired Alpharma Pharmaceuticals in 2008. King swung to a first-quarter profit of $4.5 million, or 2 cents a share, from a loss of $11 million, or 4 cents, a year earlier. Still, the operating margin contracted to 7.7% from 19%. King trades at a PEG ratio, a measure of value relative to predicted long-run growth, of 0.1, signaling a 90% discount to estimated fair value. Analysts are bullish on the stock, with eight, or 53%, ranking it a "buy."

6. Office Depot ( ODP), seller of supplies, software and furniture, has slumped 36% this year. The company swung to a first-quarter profit of $29 million, or 7 cents a share, from a loss of $55 million, or 20 cents, a year earlier. Revenue declined 4.8%. The operating margin remained in shallow positive territory at 1.8%. Office Depot shares sell for a price-to-projected-earnings ratio of 20, a 31% premium to the industry average. However, the stock's book value multiple of 1, sales multiple of 0.1 and cash-flow multiple of 4.5 indicate discounts to peers.

5. Tax-preparer H&R Block ( HRB) has suffered a 36% drop in share value this year. Its stock now offers a dividend yield of 4.2%. Fiscal fourth-quarter net income decreased 2.3%, to $691 million, but earnings per share gained 1.4%, to $2.11, boosted by a smaller float. The operating margin remained steady at 48%. High unemployment and the ongoing threat from tax-preparation software such as TurboTax, a product of Intuit ( INTU), are hurting H&R shares. The stock trades at a price-to-projected-earnings ratio of 7.9, a discount of 65% to its peer average.

4. Dean Foods ( DF) sells dairy products and substitutes, including the Silk soy milk and Land O' Lakes brands. First-quarter profit plummeted 43%, to $43 million, or 23 cents a share, as revenue climbed 10%. The operating margin narrowed to 4.1% from 7.5%. During the past three years, Dean Foods shares have fallen 30% annually, on average. But former snack-food subsidiary Treehouse Foods ( THS) has returned 22% a year over the same span. Dean sells for a price-to-projected-earnings ratio of 9.3, a 38% discount to its peer average.

3. AK Steel Holding ( AKS) produces flat-rolled carbon, stainless and electrical steel. Its stock has fallen 41% this year. The company swung to a first-quarter profit of $1.9 million, or 2 cents a share, from a loss of $73 million, or 67 cents, a year earlier. Revenue surged 52%. The operating margin turned positive. AK Steel trades at a price-to-projected-earnings ratio of 7.3, a price-to-book ratio of 1.6 and a price-to-sales ratio of 0.3, reflecting discounts of 60%, 43% and 95% to metals and mining industry averages. The stock has dropped 31% a year since 2007.

2. Monsanto ( MON) sells seeds, fertilizers and herbicides. During the past three years, it has grown sales 7.6% annually, on average. Its stock has corrected 42% this year. Fiscal third-quarter profit decreased 45%, to $384 million, or 70 cents a share, as revenue declined 6.3%. Monsanto missed analysts' median earnings estimate by 9 cents due to weak pricing for herbicides. The operating margin tightened to 22% from 33%. Monsanto sells for a price-to-projected-earnings ratio of 16 and a price-to-sales ratio of 2.5, premiums to chemicals peers.

1. Chip maker Nvidia ( NVDA) has plummeted 45% this year. The company swung to a fiscal first-quarter profit of $138 million, or 23 cents a share, from a loss of $201 million, or 37 cents, a year earlier. Revenue advanced 51%. Nvidia sells for a price-to-projected-earnings ratio of 9.8 and a price-to-book ratio of 2.1 -- 27% and 23% discounts to respective semiconductor industry averages. Of analysts following Nvidia, 11, or 34%, rate its stock "buy", 19 rate it "hold" and two rank it "sell." Nvidia has $1.8 billion of cash, equaling a quick ratio of 3, and $24 million of debt.

-- Reported by Jake Lynch in Boston.

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