NEW YORK ( TheStreet) -TheStreet Ratings' stock model upgraded Pharmaceutical Product Development Inc ( PPDI) to 'Buy' from 'Hold'. Net income at this $3.6 billion market cap, drug researcher grew by 152% to a profit of $47.9 million compared to the prior fourth quarter.

TheStreet Ratings released rating changes on 11 U.S. common stocks for April 6, 2011. In total, seven stocks were upgraded and four stocks were downgraded by our stock model.

In the fourth quarter, Pharmaceutical Product Development reported $389 million in revenue, an increase of 8.7% compared to the year earlier quarter. Learn more about Pharmaceutical Product Development: Company Profile, Income Statement, Balance Sheet, Stock Ratios, Analyst Ratings.

$1.3 billion market cap, online ad company, ValueClick Inc ( VCLK) was upgraded to 'Buy' from 'Hold'. In fourth quarter results, ValueClick reported a net income of $21.1 million, up 35.9% compared to the year earlier quarter. Over the same time period, revenue increased by 16.6% to $129 million. Learn more about ValueClick: Company Profile, Income Statement, Balance Sheet, Stock Ratios, Analyst Ratings.

-- Reported by Kevin Baker in Jupiter, FL.

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Kevin Baker became the senior financial analyst for TheStreet Ratings upon the August 2006 acquisition of Weiss Ratings by TheStreet.com, covering equity and mutual fund ratings. He joined the Weiss Group in 1997 as a banking and brokerage analyst. In 1999, he created the Weiss Group's first ratings to gauge the level of risk in U.S. equities. Baker received a B.S. degree in management from Rensselaer Polytechnic Institute and an M.B.A. with a finance specialization from Nova Southeastern University.