During an Initial Public Offering (IPO), the prospectus is one of the most important information sources for investors to valuate the company. Recent studies on e.g. annual reports give evidence that investors react differently, based on the textual complexity (measured e.g. by Fog-Index / Flesch-Kincaid-Index) of the publication. This thesis aims to answer the following questions: Are investors biased by textual complexity during IPOs as well? Can textual complexity be seen as a proxy for uncertainty and hence is there a linkage between complexity and underpricing, volatility and stock performance during the first days of trading? The thesis should be written in English as most relevant literature about this topic is available in English. A partially existent data sample can be used and should be expanded during the thesis.