Fitbit surged 52 percent to $30.9 a share (26.7 euros) following its initial public offering (IPO) on Wall Street Thursday - up singificantly from its IPO price of $20, and valueing the San Francisco-based fitness specialist at about $4 billion.

Fitbit sold 22.4 million shares, raising $448 million. Its stockholders sold another 14.2 million shares, worth about $284 million.

The company produces devices that can be worn on the wrist or clipped to clothing to monitor daily steps, calories burned, and grab other fitness data.

When Fitbit announced going public in early May, it cited society's increasing emphasis on health and fitness as a large factor of success.

Strong performance

The startup has been around since 2007, and unlike many other competitors has been able to hit profitability levels fairly quickly.

In the first quarter of 2015, Fitbit booked a net profit of little under $48 million (42.7 million euros) on revenues totaling almost $337 million. Since its founding, the firm has sold some 20 million fitness tracking devices to customers.

While Fitbit is reaping the profit of wearable technology, its competitor, Jawbone, has hit the company with two lawsuits in the last few weeks. In the most recent, filed on June 10, Jawbone and its owner AliphCom claim patent infringement by Fitbit's wearable technology line.

In the first lawsuit, Jawbone alleges that Fitbit poached five of its employees who allegedly divulged company information. Jawbone indicated it would also file a complaint with the International Trade Commission, a move that could complicate foreign trade in Fitbit products.

Fitbit and Jawbone are pioneers in the market for fitness bands, but both are under attack from outside companies such as the Chinese smartphone-maker Xiaomi and Apple's Apple Watch.

uhe/pad (dpa, AP)