A pair of Chinese firms, 500.com Limited and Sungy Mobile Limited, saw their stocks roar on Friday when they made debut on the US stock markets.

After its first day of trading on the New York Stock Exchange, stocks of China's leading online sports lottery service provider 500.com Limited closed at 20.01 dollars per share, up almost 54 percent from the price of its initial public offering (IPO).

The company said it priced its IPO of 5,786,000 American Depositary Shares (ADSs) at 13.00 US dollars each with a total offering size of 75.2 million dollars. One ADS represents 10 Class A ordinary shares of the company.

"Without any doubt, to choose the United States and trade our stocks on the New York Stock Exchange will improve our brand rapidly and increase our competitiveness against them (other online lottery companies)," Man San Law, founder, chairman and chief executive officer of 500.com told Xinhua.

Competition comes from portals like Taobao and Tencent, which have their own brands, lottery channels and large amount of website traffic, he said, adding 500.com will try to enhance its specialty and services to sharpen its competitive edge.

On the same day, stocks of Sungy Mobile, a leading global provider of mobile internet products and services, rallied nearly 19 percent to close at 13.35 dollars a share.

It set its IPO on the floor of NASDAQ Global Market under ticker symbol GOMO.

Sungy Mobile said in a statement released Friday that it priced 7,000,000 ADSs at 11.22 dollars each with a total offering size of 78.54 million dollars. One ADS represents six Class A ordinary shares.

Sungy Mobile mainly provides applications and mobile platform development. Its platform product GO Launcher EX manages apps, widgets and functions on Android smartphones and serves as users' first entry point to their phones.