Robin Feldman and Tom Ewing have published an article in the Stanford Technology Law Review called "The Giants Among Us." Here is an excerpt:
The patent world is quietly undergoing a change of seismic proportions. In a few short years, a handful of entities have amassed vast treasuries of patents on an unprecedented scale. To give some sense of the magnitude of this change, our research shows that in a little more than five years, the most massive of these has accumulated 30,000-60,000 patents worldwide, which would make it the 5th largest patent portfolio of any domestic US company and the 15th largest of any company in the world.
Although size is important in understanding the nature of the shift, size alone is not the issue. It is also the method of organization and the types of activities that are causing a paradigm shift in the world of patents and innovation.
These entities, which we call mass aggregators, do not engage in the manufacturing of products nor do they conduct much research. Rather, they pursue other goals of interest to their founders and investors. Non-practicing entities have been around the patent world for some time, and in the past, they have fallen into two broad categories. The first category includes universities and research laboratories, which tend to have scholars engaged in basic research and license out inventions rather than manufacturing products on their own. The second category includes individuals or small groups who purchase patents to assert them against existing, successful products. Those in the second category have been described colloquially as “trolls,” which appears to be a reference to the children’s tale of the three billy goats who must pay a toll to the troll waiting under the bridge if they wish to pass. Troll activity is generally reviled by operating companies as falling somewhere between extortion and a drag on innovation. In particular, many believe that patent trolls often extract a disproportionate return, far beyond the value that their patented invention adds to the commercial product, if it adds at all.
Here is the link: