Internet-based technologies have opened new opportunities for conducting business within and across enterprises that were never possible a few years ago. This paper presents our experience in using Web services for prototyping a service-oriented architecture for Capital Market Systems (CMSs). Our work exposes a world-class surveillance system?s functionality into a number of Web services. Our work also includes benchmarking the performance of this legacy system and investigating the associated overheads of using SOAP as a wire format for Web services. Even though other research studies have tried to explain SOAP?s performance inef.ciency, there is lack of studies that evaluate SOAP in the context of a realistic business application. This initial investigation shows that system?s integration opportunities introduced by Web services can outweigh the performance overheads. This occurs in some aspects of real-time CMSs that are not performance-demanding such as the dissemination of market alerts to the analysts.