Abstract: Today, traded cloud services are governed by service-level agreements that specify providers' obligations, such as availability and reliability. Violations of service-level agreements result in penalty payments. The recent development of prominent cloud platforms, such as the redesign of Amazon's spot marketspace, underpins a trend towards dynamic cloud markets where consumers continuously migrate their services across different marketspaces and providers to reach a cost optimum. This leads to a heterogeneous IT infrastructure and, consequently, complicates monitoring of delivered service quality. Hence, there is a need for a transparent penalty management system that ensures consumers automatically receive penalty payments from providers for service violations. In this paper, we present a cloud monitoring system that can autonomously execute penalty payments. In this regard, we use smart contracts hosted on blockchains that continuously monitor cloud services and trigger penalty payments to consumers in the event of service violations. For justification and evaluation, we implement our approach using the IBM Hyperledger Fabric framework and create a use case with Amazon and Azure cloud services to illustrate the universal design of the presented mechanism.