Bill Gates has quietly created a brand new company, complete with high-tech office space, a cryptic name and its own trademark.

The new endeavour - named bgC3 - is said to be a "think tank", based at a Kirkland office, apparently a short drive from 53-year-old Gates' home on Lake Washington.

The name apparently comes from "bg" for Bill Gates, "C" for catalyst and "3" as it's Gates' "third place" after Microsoft and the charitable foundation he runs with his wife Melinda.

Apparently not a commercial venture but a "vehicle to coordinate the software mogul’s work on his business and philanthropic endeavors", bgC3 will encompass Gates' personal pursuits in ideas in science and technology.

US Federal trademark filings categorise the company under the afore-mentioned "think tank" tag for areas including "scientific and technological services", "industrial analysis and research" and "design and development of computer hardware and software".

Visitors to the bgC3 offices say it's "fully stocked with Microsoft technologies, including a Surface tabletop computer with a virtual guestbook application".