Public interest in investments has increased dramatically during the past decades. Also parallely, there has been much research interest related with profitability, liquidity, and statutory and regulatory protection of investments, the three important pillars of investment. However, there is no similar research comparing the markets of Spain, USA and Russia in order to answer the research question of this thesis. Considering these factors, there exists need for this scientific research. The objective of this study was to discover the effect of statutory and regulatory protection in investment decision by comparing and analysing the legal environment of investments. The two steps to achieve this objective were: - Analyse and compare the legislation and securities market regulation international, national and institutional framework. - Survey. On a national level, we focused on three markets - Spain, the USA and Russia. On an institutional level, we concentrated on state agencies with regulatory power over securities markets of the above mentioned countries. The conclusion answered the main question of the work – “How does statutory and regulatory protection affect investment decisions?” This thesis in financial and business law is very relevant and will be of great interest to the investment sector. It can help interested parties in investment societies find specific solutions to improve the efficiency in investments in the above mentioned securities markets taking into consideration statutory and regulatory protection. Also, this work raises new questions for future research and indicates new possibilities of conducting future investigations. / Vicerrectorado de Investigación y Transferencia de Conocimiento (Escuela de Doctorado) "Convocatoria para la concesión de subvenciones con el objetivo de facilitar la obtención de la mención de Doctor internacional en el título de doctora o doctor, Ayudas Movilidad 2015". Jeffrey E. Smith Institute of Real Estate and Capital Markets of University of Missouri "Research Scholar (Becario de Investigación) - 01/02/2016-31/12/2017".