Seminar paper from the year 2015 in the subject Economics - Finance, grade: 1,3, University of Applied Sciences Essen, language: English, abstract: The process of making decisions on the financial market is influenced by various factors and involves a relatively complex behaviour. In general two factors drive the process, one the financial model, that represents the correlation of risk and return and second the internal factors determined by skill level, investment portfolio and education. This work at hand distinguishes between traditional and modern theory of financial markets. The Efficient Market Hypothesis (EMH) explains that investors act rationally and make economic decisions on a rational basis. These process of decision making is explained in the Expected Utility Theory and assumes that investors are doing everything to optimize their performances, which correlates with the term homo oeconomicus. The behavioural financial theory, taken as the modern theory, basically handles individual circumstances that result in decision makings on the market. This work at hand will work out the changes that proceeded over the years and try to explain which way is more sufficient for analysing and understanding occasions on the financial market. The aim is to impart, how behavioural finance tries to explain the financial market with help of models. Furthermore possible shortcoming or critics of these models shall be shown.