Capitalization table (cap table) is a public ledger that tracks the equity ownership of a company’s shareholders. For start-up and non-public companies this information is usually stored in a spreadsheet but even after just a couple of investment rounds the cap table can become highly complex. A factor that further increases the complexity is the need for entrepreneurs and investors to use the data for analysis and calculations for future decision making. The purpose of the thesis has been to create a design hypotheses of a usable graphical user interface that allows shareholders to more clearly understand the ownership situation of the company and future scenario. To answer the research question a user-centered design approach along with a case study was applied. The case study was chosen and performed on a start-up that already offers a web service for better management of corporation documents so that real users could be part of the design process and so that their needs could be analysed. After three iterations, an end result (implemented in AngularJS and TypeScript) was obtained, which can be split into two equal parts. Firstly, a view containing a timeline of the company and its current ownership. The view can also be used to get a snapshot of the company’s ownership in a specific point in time and to simulate how future investment rounds could dilute the current shareholder’s ownership. Secondly, a view where users can simulate future exit scenarios and how much each shareholder will earn in an exit.