Patent trolls could have cost US businesses as much as $500 billion in stock value over the last 20 years, according to Boston University researchers.
The team looked at stock prices between 1990 and 2010 to establish just how much corporate value was lost when an organization was sued for patent violation.
The average loss to a company's stock value following a patent lawsuit, says the team in its report, was a whopping $122 million.
And they found that the problem is getting worse, with nearly two thirds of that half-trillion dollars having been lost in the last four years.
And, while patent-holding companies insist that they only want to benefit inventors, this doesn't appear to be the case, as the benefits to creators haven't increased by anything like the same proportion.
For those complainants that were also publicly traded companies, revenue was just $7.6 billion - while the losses to the defendants was $88 billion. Somebody - lawyers perhaps - is creaming off the difference.
"Thhe characteristics of this litigation are distinctive: it is focused on software and related technologies, it targets firms that have already developed technology, and most of these lawsuits involve multiple large companies as defendants. These characteristics suggest that this litigation exploits weaknesses in the patent system," say the authors.
"The scope of these patents is not clear, they are often written in vague language, and technology companies cannot easily find them and understand what they claim. It appears that much of the NPE [non-practicing entity] litigation takes advantages of these weaknesses."