In the past, non-practicing entities (NPEs) - firms that license patents without producing goods - have facilitated technology markets and increased rents for small inventors. Is this also true for today's NPEs? Or are they “patent trolls” who opportunistically litigate over software patents...

The emergence of nonpracticing entities (NPEs) — firms that purchase and hold patent rights but neither innovate themselves nor use the patents in the production of goods — is supposed to incentivize innovation by providing a ready market for innovators. We test this idea empirically and...