This thesis contains three parts that are all connected by their contribution to research about the effects of trading apps on investment behavior. The primary motivation for this study is to investigate the previously undetermined consequences and effects of trading apps, which are a new phenomenon in the broker market, on the investment and risk behavior of Neobroker users. Chapter 2 addresses the characteristics of a typical Neobroker user and a former Neobroker user and the impact of trading apps on the investment and risk behavior of their users. The results show that Neobroker users are significantly more risk tolerant than the general German population and are influenced by trading apps regarding their investment and risk behavior. Low trading fees and the low minimum investment amount are the main reasons for the use of trading apps. Investors who stop using trading apps mostly stop investing altogether. Another worrying result is that financial literacy among all groups is low and most Neobroker users have wrong conceptions about how trading apps earn money. In general, the financial literacy of all groups considered in this chapter is surprisingly low. The third chapter investigates the effects of trading apps on investment behavior over time and compares the investment and risk behavior of Neobroker users and general investors. By using representative data of German Neobroker users, who were surveyed repeatedly over a 8-month time interval, it becomes possible to determine causal effects of the use of trading apps over time. In total, the financial literacy of Neobroker users increases with the longer use of a trading app. A worrying result is that the risk tolerance of Neobroker users rises significantly over time. Male Neobroker users gain a higher annual return (non-risk-adjusted) than female Neobroker users. In comparison to general investors, Neobroker users are significantly younger, more risk tolerant, more likely to buy derivatives and gain a higher annual return (non-risk-adjusted). The fourth chapter analyses the impact of personality traits on the investment and risk behavior of Neobroker users. The results show that the BIG-5 personality traits have an impact on the investment behavior of Neobroker users. Two personality traits, openness and conscientiousness, stand out the most, as these two have explanatory power over various aspects of the behavior of Neobroker users. In particular, whether they buy different financial products than planned, the time they inform themselves about financial markets, the variety of financial products owned, and the reasons to use a Neobroker. Surprisingly, the risk tolerance of Neobroker users and the reasons to invest are not connected to any personal dimension. Whether a participant uses a trading app or a traditional broker to invest is respectively influenced by different personality traits.