Cost overrun is prevalent in the construction industry. Usually, an owner sets a budget at the preliminary phase of a project which changes over time. Past studies are focused on analyzing the cost growth of design-bid-build projects during construction. Limited efforts have been made to analyze details of projects delivered with the Construction Manager General Contractor (CM/GC) method. This study tracks and analyzes the construction cost variation of a project from the conceptual phase to the design completion phase. The analysis is presented with a case study of a new stadium construction project. It identifies that the changes in the scope and design of the project due to the change in available budget were a major reason for variation in the cost estimates over time. Further, this study identifies a) trades with the highest variation in subcontractors’ bids, b) trades that were most overestimated, and c) trades that were most underestimated. The findings of this study is expected to aid owners, designers, and contractors of future projects in improving the preparation, planning, and estimating of future projects; reducing cost variation within trades; and optimizing the amount of contingency required to ensure the successful completion of similar projects.