Shares of Mixi Inc. ended their second day of trading on the Tokyo Stock Exchange at 3.12 million yen Friday, up from the initial price of 2.95 million yen fetched in the morning.

Mixi's stock rose after a massive wave of buy orders prevented deals from being struck Thursday, when Japan's most popular social networking Web site debuted on the Tokyo Stock Exchange's Mothers market for startups.

Based on Friday's closing price, Mixi's market capitalization stands at 219 billion yen, making it the second-largest Mothers issue by value after mobile phone software developer Access Co.

One broker, who asked not to be named, implied that investors were too enthusiastic about the stock. Other analysts echoed that view, saying the company hasn't explained how its large membership will translate into profits.

By Thursday's close, bids stood at 3.15 million yen per share, more than double its initial public offering price of 1.55 million yen.

Membership in Mixi, which was launched in February 2004, is by invitation only and stood at more than 5 million as of July. Mixi members can exchange personal profiles and other information, and share online diaries.

Analysts said Mixi has drawn strong interest from individual investors.

They pointed out that expectations for the Internet firm, run by 30-year-old President Kenji Kasahara, Japan's newest overnight millionaire, will grow along with its advertising revenue and could help investors regain confidence in startups, which suffered a setback in the wake of the Livedoor Co. group's sudden fall from grace amid allegations of accounting fraud.

Livedoor was delisted from the Mothers market in April.