The bgC3 logo.

Just months after his Microsoft farewell, Bill Gates is quietly creating a new company -- complete with high-tech office space, a cryptic name and even its own trademark.

Public documents describe the new Gates entity -- bgC3 LLC -- as a “think tank.” It’s housed within a Kirkland office that the Microsoft co-founder established on his own after leaving his day-to-day executive role at the company this summer.

Is this Bill Gates’ next big business? A Gates insider gives an emphatic no  -- saying it’s not a commercial venture but rather a vehicle to coordinate the software mogul’s work on his business and philanthropic endeavors.

However, bgC3 will also oversee Gates’ personal pursuit of breakthrough ideas in science and technology. The insider said the goal isn’t necessarily to create new companies, although ideas could be passed along to Microsoft, the Bill & Melinda Gates Foundation -- or others – as it makes sense.

Whatever the ultimate role of the company, the circumstances surrounding its creation provide a behind-the-scenes glimpse into the new era of Gates’ life.

State records show that the company, originally called Carillon Holdings, was established in March 2008. It formally changed its name to bgC3 in early July, 10 days after Gates left his full-time job at the company he built into an industry giant. He remains Microsoft’s chairman and continues to work part-time on projects.

The records describe bgC3 as a “holding company” headquartered in Kirkland –a relatively short, picturesque drive from Gates’ home on Lake Washington.

Federal trademark filings provide more clues – describing bgC3 as a think tank, under a generic trademark classification that corresponds broadly to areas including "scientific and technological services," "industrial analysis and research," and "design and development of computer hardware and software."

But what does bgC3 mean? The logical assumption might be “Bill Gates Company Three” – his third enterprise after Microsoft and the Bill & Melinda Gates Foundation. But that’s only partially right, according to the Gates insider.

The “bg” is Bill Gates, the insider says, but the “C” stands for “catalyst.” The idea is that Gates will play that role as he brings together new people and ideas. The “three” reflects the notion of a third place, apart from Microsoft and the foundation.

Before beginning his transition this summer, Gates told reporters that he would focus full-time on the foundation, and part-time on selected Microsoft assignments.

He acknowledged plans for his own office in Kirkland, apart from Microsoft and the foundation, but didn't discuss specifically any plans to organize that office under a new company. At the same time, he said he would be open to personally supporting breakthrough ideas where he sees a chance to advance the state of mankind.

It's not clear exactly where those interests will lead, or precisely what role bgC3 will play in the long run. But Gates, who turns 53 next week, has increasingly expanded his focus beyond Microsoft to problems of technology, science and society.

Much of that broader focus has come through the Gates Foundation, which deals in issues of education and global health. People associated with Gates say he is still expected to focus primarily on the foundation in this new era of his life.

But particularly at a time of economic turmoil, Gates' status and wealth could put him in a position to bring in top scientists and other notable people to work with bgC3. Gates has historically surrounded himself with smart people, and he’s famously thirsty for knowledge. His interests go well beyond computer science into fields as disparate as energy, biotechnology, and global economics.

The concept of a technological think tank wouldn’t be new to Gates. He has taken part in high-powered brainstorming sessions organized by his friend, Nathan Myhrvold, Microsoft's former chief technology officer, who now heads a company called Intellectual Ventures LLC, based in Bellevue. Projects that Gates is backing through Myhrvold include an effort to create an alternative nuclear reactor that produces clean power without waste or proliferation.

Whatever its aims, the new Gates organization doesn't appear to have ambitions of becoming another behemoth. In a letter last year to a Kirkland city official, a Gates representative wrote that total occupancy would be limited to between 40 and 60 people, including employees and visitors, in the space that bgC3 now occupies.

At the same time, it’s no ordinary office space. Visitors say it’s fully stocked with Microsoft technologies, including a Surface tabletop computer with a virtual guestbook application.

Some of bgC3’s activity has been recent. According to the U.S. Patent and Trademark database, the company filed Sept. 29 for federal trademarks on "BGC3" and the "C3" logo. The latter (pictured above) is an intertwined "C" and "3" in block letters.

The Microsoft chairman has established companies before to serve specific purposes, primarily behind the scenes. Watermark Estate Management Services LLC oversees many of Gates’ personal and family matters, and Cascade Investments LLC oversees his stock and other financial holdings.

Several of Gates’ associates are named in the documents tied to bgC3, although Gates himself isn't identified by name in public records associated with the company – a main reason its existence hasn't received media attention until now.

John Cook contributed to this report.