This document is a guide on Trading Systems as-a-Service, focusing on the adoption of as-a-Service models within Capital Markets. It outlines how these models represent a shift towards standardized and mutualized operating frameworks, enhancing operational efficiency. The guide details the benefits of a fully cloud-hosted and managed solution, emphasizing Agile principles and the flexibility they bring to trading systems. It explains how clients can maintain control over their applications while benefiting from automated testing and continuous integration/deployment processes. The document also discusses the cost reduction potential of up to 50% in managing trading estates, the importance of evergreening for keeping applications current, and the streamlined management of third-party applications. Additionally, it highlights the support structure provided by Luxoft, which includes disaster recovery and 24/7 operational support. The guide concludes by reinforcing the value of partnering with Luxoft for improved agility and reduced complexity in trading application management.