SINA ( SINA) is a leading Internet media company in China. As a provider of reliable online news and information, it has attracted a well-educated and relatively wealthy user group, demographics that make it a particularly appealing venue for advertisers. The firm has more than tripled its revenue over the past seven years.

Sina generates about 70% of its revenue from online advertising, with the rest coming from wireless value-added services.

Its shares are up 56% this year and 184% over the past year, giving it a market value of $6 billion.

ThinkEquity analysts have a "hold" rating on its shares and said in a March 18 research note that it thinks its shares are now fully valued.

Morningstar analyst Dan Su said in a March 24 research note that Morningstar has the company "under review" to reassess its operating valuations.

The company recently said it dropped the Google ( GOOG) search service from its Web site and is now using its own search technology. Google has said that it would phase out its censored search contracts in the country.

The company also owns Sina Weibo, a Chinese micro-blogging site similar to Twitter. It was launched in August 2009 but is still under development.

ThinkEquity says it has cut its earnings per share estimates for 2011 by 16% to $1.67 per share and by 13% in 2012 to $2.10 per share, "as we now assume a greater level of investment for Sina Weibo as Sina aggressively builds out the platform as well as marketing of Weibo. We believe the investments in Weibo are the right strategic move for Sina, though we believe shares are currently fully valued."

Fidelity owns 9% of Sina's shares, followed by T. Rowe Price, at 8%. Institutional investors own 91% of the company's outstanding shares.

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