Shares of Mixi Inc., Japan's most popular social networking site, shot up during the company's stock market debut Thursday as buy orders swamped sell orders and more than doubled its initially offered price.

As a result, no deals could be struck and the bidding price stood at 3.15 million yen per share at the end of the days' trading, more than double its initial public offering price of 1.55 million yen.

The stock, which debuted on the Mothers market at the Tokyo Stock Exchange, is capitalized at 109.2 billion yen, based on the IPO price, making it the seventh-largest issue on Mothers.