UPDATE 2-Sina quarterly profit up 49 pct on advertising

(Adds company forecast, CEO comments, COO promotion)

LOS ANGELES, Feb 20 (Reuters) - Chinese Internet portal Sina Corp (SINA.O) said on Wednesday its fourth-quarter profit grew 49 percent as advertising revenue rose.

Shanghai-based Sina, which provides news, games, shopping and other Internet-based services to Chinese at home and abroad, posted a profit of $17.5 million, or 29 cents per share, for the three months ended Dec. 31, compared with $11.7 million, or 20 cents per share, in the year-ago period.

The company's adjusted net income of 34 cents per share beat an average forecast of 33 cents per share, according to Reuters Estimates.

Revenue grew 25 percent to $70.7 million from $56.4 million over the same period.

Wall Street had forecast average fourth quarter revenues of $69.24 million, Reuters Estimates showed.

The company forecast first quarter revenues of between $66 million and $68 million, with advertising revenues making up between $45 million and $46 million.

Analysts, on average, had forecast first quarter revenues of $66.14 million for Sina, according to Reuters Estimates.

Sina also estimated that its first quarter stock-based compensation will be between $3.5 million and $4 million, excluding any new shares that may be issued.

The company also estimated its effective tax rate under the new Chinese Enterprise Income Tax Regulation to be between 14 percent and 25 percent.

Sina Chief Executive Charles Chao said the company's advertising business remains strong and that, for the first time in two years, its mobile value-added service business saw a quarter-over-quarter increase.

Chao said in a statement that the company's mobile business was "showing signs of stabilization."

The company also announced the promotion of Hong Du, senior vice president of sales and marketing, to chief operating officer.

Sina shares rose 44 cents, or 1 percent, in light extended trading on Wednesday, after closing down 25 cents, or 0.6 percent, at $42.96 on Nasdaq. (Reporting by Gina Keating, editing by Richard Chang and Tim Dobbyn)