Called patent trolls or non-practising entities (NPE), companies that make most of their money from licensing patents don't have the best reputation.
Just this week, the Wall Street Journal reported U.S. antitrust authorities are probing whether these firms are making high-tech markets less competitive.
Indeed, many tech companies live in fear of NPEs.
It's tough to quantify which NPEs are the most feared, since many NPE's simply threaten to sue companies, patent expert James Bessen told Business Insider.
The scariest NPEs, however, tend to be the ones with the biggest patent arsenals, Bessen said. Those companies typically also have the resources to file suit if they want.
With that in mind, BI ranked NPEs based on their number of patents and publicized patent applications as of July 2012 reported by PatentFreedom, a group that provides research for patent defendants.
Note: PatentFreedom defines an NPE as any company that derives the majority of its income from licensing patents. Some of the NPEs listed, like Tessera, also invest in research and development.
BI reached out to every ranked company for which contact information was available.
8. Acacia Technologies
U.S. patents and patent applications estimated by PatentFreedom: 1,316
What we know about the company: Inventors and patent owners hire Acacia to license their IP to corporations. Patent owners split the licensing revenue with Acacia.
Acacia says its licensees include Sony, Exxon, Microsoft, and other huge companies.
Columbia Business School professor Raymond Fishman recently profiled Acacia in a story called "The Troll Toll," contending it and companies like it stifle innovation.
But Acacia CEO Paul Ryan told BI that people who use the term patent troll are just "name calling."
"The issue is if you have valid infringed patents people should pay you for the use of the use of the patents," Ryan said.
7. Tessera Technologies Inc.
U.S. patents and patent applications estimated by PatentFreedom: 1,375
What we know about the the company: Tessera began as a semiconductor maker but then realized its "core value" was in licensing its technology, according to the company's website.
Tech adviser Roy Kaller has written that "companies like Tessera" and others are not so affectionately referred to as patent trolls in the industry.
"They don't have much in the way of a sales force, but they are expert intimidators and litigators," Kaller wrote.
Tessera did not immediately respond to a request for comment from BI.
6. Rambus
U.S. patents and patent applications estimated by PatentFreedom: 1,696
What we know about the company: Tech blogger Joel Hruska wrote for HotHardware that Rambus is not just a patent troll but "the patent troll." Hruska says Rambus had made litigation its top money-making priority for more than a decade.
In September, a judge sanctioned Rambus for destroying evidence in its patent fight against SK Hynix Inc.
Rambus stressed in a statement to BI that it creates the technology it patents, and that the majority of its workers are engineers and inventors.
See the rest of the story at Business Insider
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