This research focuses on the question of valuation of start-ups and young companies, which is an increasingly relevant and complex subject, due to the challenges faced by founders, investors and analysts in the valuation process. In the theoretical part, the concepts of start-up and valuation will be addressed, as well as the challenges which make this process demanding, together with suggestions by relevant experts, primarily Professor A. Damodaran, on how to mitigate these challenges. The paper will explore intrinsic and relative valuations as the main valuation methods adjusted for characteristics of young companies, as well as several of the main valuation methods developed specifically for start-ups, analyzing their advantages and disadvantages. In the empirical part, the theoretical insights will be applied on the valuation of WeWork Inc. and the comparison of the results with the valuation of the company in 2019, when the company had one of the least successful IPOs in history.