In March 2018 the European Commission published the Action Plan on Financing Sustainable Growth. One of the main objectives with the actions presented in the action plan is to reorient capital flows towards sustainable investments, i.e. to influence more investors to invest sustainably. The action plan was followed by three proposals for transparency regulation regarding an EU taxonomy on sustainability, sustainability benchmarks and sustainability disclosures. Furthermore, the action plan included actions regarding two other transparency measures – sustainability labels and sustainability ratings. The first purpose of the thesis is to investigate if transparency regulation in the EU can be used as a tool to influence investors to choose sustainable investment funds. One of the main aims of the actions presented in the Action Plan on Financing Sustainable Growth, as well as the accompanying regulation proposals, is to reorient capital flows towards sustainable investments, i.e. to influence more investors to invest sustainably. In light of this, the Commission’s three proposed transparency regulations, as well as the concept of sustainability labels and ratings, are used as a basis for the investigation. The second purpose of the thesis is therefore to critically review the three regulation proposals and the concept of sustainability labels and ratings in order to gain an understanding of how different transparency measures can influence investors to choose sustainable investment funds. The transparency regulations and measures are analysed and critically reviewed in light of their objective to influence more investors to invest sustainably. A behavioural economics perspective, as well as consumer behaviour theories and decision-making models, are applied in order to analyse the transparency regulations and measures from an external perspective. Based on the analysis there are many indicators that transparency regulation can be used as a tool to influence investors to choose sustainable investment funds. However, to what extent transparency regulation can influence investor behaviour varies depending on which transparency measures are used and how they are designed. Sustainability benchmarks seem to have the least potential to influence investor behaviour, while the EU taxonomy on sustainability and sustainability labels seem to have the best potential to influence investor behaviour.