In 2011, United States business entities incurred $29 billion in direct costs because of patent trolls. Lawsuits brought by "patent assertion companies" made up 61% of all patent cases in 2012, according to the Santa Clara University School of Law. From 2009 through mid-2013, Apple Inc. was the defendant in 171 lawsuits brought by non-practicing entities (NPEs), followed by Hewlett-Packard (137), Samsung (133), AT&T (127), and Dell (122). Patent troll-instigated litigation, once mostly confined to large companies in patent-dependent industries such as pharmaceuticals, came to involve companies of all sizes in a wide variety of industries. In 2005, patent trolls sued 800 small firms (those with less than $100 million annual revenue), the number growing to nearly 2,900 such firms in 2011; the median defendant's annual revenue was $10.3 million. A July 2014 PricewaterhouseCoopers study concluded that non-practicing entities (NPEs) accounted for 67 percent of all patent lawsuits filed—up from 28 percent five years earlier—and though the median monetary award size has shrunk over time, the median number of awards to NPEs was three times higher than those of practicing companies.

A 2014 study from Harvard University, Harvard Business School and the University of Texas concluded that firms forced to pay patent trolls reduce R&D spending, averaging $211 million less than firms having won a lawsuit against a troll. That 2014 study also found that trolls tend to sue firms with fewer attorneys on staff, in effect encouraging firms to invest in legal representation at the expense of technology development. The 2014 study reported that trolls tend to opportunistically sue firms with more available cash, even if the firm's available cash was not earned in the technology that is the subject of the patent lawsuit, and targeting the firms long before a product begins turning a profit, thus disincentivizing investment in new technologies.

Emphasis became progressively focused on patents covering software rather than chemical or mechanical inventions, given the difficulty in defining the scope of software patent claims in comparison to the more easily defined specific compounds in chemical patents. A GAO study concluded that the proportion of patent lawsuits initiated by trolls hadn't changed significantly from 2007 through 2011, the GAO speculating that the raw numerical increase in both troll and non-troll instituted lawsuits may be due to the "inherently imprecise" language and a lack of common, standardized, scientific vocabulary in constantly evolving emerging technologies such as software. Software patents were described as "particularly prone" to abuse because software is "inherently conceptual", with research indicating that a software patent is four times as likely as a chemical patent to be involved in litigation, and a software "business method patent" is thirteen times more likely to be litigated.

On June 4, 2013, the National Economic Council and Council of Economic Advisers released a report entitled Patent Assertion and U.S. Innovation that found significant harm to the economy from such entities and made recommendations to address them. The report further stated: "Specific policies should focus on fostering clearer patents with a high standard of novelty and non-obviousness, reducing disparity in the costs of litigation for patent owners and technology users, and increasing the adaptability of the innovation system to challenges posed by new technologies and new business models, would likely have a similar effect today."