A major obstacle in preparation of the project and understanding of the software was the fact that the Delphi-based source code of the program had been developed by several developers working with inconsistent quality, and the application suffered many promiscuous changes without any documentation or code-explaining comment during the previous development years. Although our client was able to explain some parts of the code, we had no comprehensive knowledge at our disposal to reconstruct the original development plans with the needed thoroughness, and the interface modules of the php-based data-service system were also of questionable quality. So finally, we have started to rebuild the software from scratch in an iterative model, assigning all tasks at the beginning of each iteration, and taking into consideration the main strategic purpose of the project, meaning the transfer of the application to a .NET-based cross-target (WPF and Silverlight) architecture, which can serve as a solid base for all further developments and allows the main systems of the application to be optimized according to the latest demands. During modernization, the system has been assigned with a new communications module making possible real-time streaming and processing of cumulated data-flow from more stock-exchanges (DAX, ATX, BUX), with new high-capacity visualization code, with a docking-enabled user surface, context-based internal help service and cloud-based data storage. After finalization of the basic structure, we’ve enhanced the original functionality of the application: new graphic tools and models, visualization modes and more than 50 new added-value functions were developed at the request of the project owner.