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20. EMC
Fortune 500 rank: 152
2010 revenue: $17.0 billion
10-year annualized return: -9.9%

EMC's stock fell prey to Mr. Market's unrealistic expectations. During the tech bubble, shares doubled in just six months -- a run-up that the network storage company's prospects never truly justified.

Recently its chief business of data storage has become popular again with investors, and EMC's 80% stake in fast-growing VMware has been a boon -- just not a big enough one for those who have owned EMC stock for a decade.   

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Last updated May 05 2011: 2:52 PM ET
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