Evidence suggests that patents facilitate technology transactions but the reasons for the effect are unclear. Patents may assist trade in technology by either: (i) protecting buyers against the expropriation of the idea (the 'appropriation effect'); or (ii) increasing information sharing during the negotiation phase through publication of technical details contained in the patent document (the 'disclosure effect'). We estimate the strength of both effects using exact matching analysis on a novel dataset of 860 technology transaction negotiations. We find evidence for the appropriation but not the disclosure effect. Technology transaction negotiations involving a granted patent instead of a pending patent (our test for the appropriation effect) are significantly more likely to be successfully completed. The appropriation effect is stronger in technology fields where patent protection is known to be more effective such as biotech, chemicals, drugs and medical. (C) 2016 Elsevier B.V. All rights reserved.