Purpose - The diffusion of the open innovation paradigm has been changing the ways in which firms acquire, manage and exploit their intangible assets. It is widely recognized that intangible assets play a relevant role for companies in creating and developing their core competences, thus yielding competitive advantage and leading to innovativeness. This paper aims at analysing the composition of intangibles portfolio of R&D intense companies and relating it to the degree of openness of their innovation processes. Further, the linkage between portfolio composition, structural features and performances of companies is investigated. Design/methodology/approach - To analyse companies' stock of intangibles, we recorded them in different categories and calculated composition ratios. In order to quantify the degree of openness of companies we considered revenues and costs from open innovation activities and investments and divestments of innovation-related intangibles, occurring in either separate acquisitions or within business combinations. Finally, different variables are used to describe structural features and performances of companies. The analysis is performed on a sample of 243 world top research and development (R&D) spending companies, according to The 2012 EU Industrial R&D Investment Scoreboard, for which the 2012 annual reports were analysed. Results are discussed from cluster, one-way ANOVA and correlation analyses. Originality/value - The paper contributes to the existing literature on the measurement of open innovation from two perspectives. First, it focuses on the pecuniary dimension of the phenomenon, using quantitative, objective data. Second, while most literature is focused on inbound metrics, our paper suggests a set of metrics which can be used for both inbound and outbound processes, allowing to define the ways in which companies can capture value from the exploitation of their technology, i.e. the business models of companies. Moreover, the paper contributes to the understanding of the relevance of intangible assets in open activities. Practical implications - The paper addresses the need for operative, practical instruments, which can help managers to monitor the impact of the investment in intangibles on companies' innovation processes after an open-oriented approach. It proposes a set of metrics enabling to evaluate their core competences and relate them to the propensity to open up innovation processes. Further, given the availability and objectivity of annual report figures, this accounting framework can also be used by decision-makers for with competitors.