After a previous deal fell through, Opera has reached an agreement to sell the mobile and desktop browser portion of its business to a group of Chinese companies for an estimated $600 million. Opera will retain its advertising business in a bid to avoid a long regulatory holdup.

The lead investor among the buyers is Kunlun Tech Co., a Beijing-based company that operates the Brothersoft desktop app store and 1Mobile Android app market. They also bought a majority stake in gay dating app Grindr earlier this year as the business tries to expand outside of its core, which is mobile game development.

The other buyer named so far is Qihoo 360, whose business is less varied than Kunlun's with most of Qihoo's efforts focused on their 360 series of anti-virus products and the ads they sell through them. Both companies are said to be trying to build themselves up to better compete with fellow Chinese corporate giants Alibaba and Tencent.

Beyond the Opera browsers for mobile and desktop platforms, Opera will sell its performance and privacy technology, the various licenses owned by the company, and Opera's stake in Chinese firm nHorizon, which also develops a browser.

Omitted from this deal is Opera's advertising arm as well as a few other minor aspects of its business, which are apparently worth $600 million themselves. The previous agreement, which included all of Opera, was for $1.2 billion. Because any deal would require regulatory approval in the United States—and the US was expected to closely scrutinize the privacy aspects of the advertising business—both sides agreed to just drop Opera's marketing arm. Fears were it could delay approval by up to a year.

Nonetheless, approval is still necessary so the deal isn't official just yet, despite the agreement.