The interconnected cloud computing paradigm is gaining considerable attention as a fundamental emerging model of cloud computing. It allows a wide range of interactions and collaborations across multiple service providers. Despite the potential advantages of interconnected clouds, establishing trust among participating parties is a challenging issue. In this paper, we introduce a lightweight trust management algorithm based on subjective logic (InterTrust) to promote trust in interconnected clouds. The experimental results demonstrate that InterTrust is capable of producing accurate trust information with significantly low execution time and high scalability compared to application of both the well-established trust management algorithm trust network analysis with subjective logic and no trust algorithm.