This paper is for investors who understand conventional investment theory (portfolio management theory, CAPM theory) and, like the author, sense that there is something not quite right with the theory. There are mistakes in the definition of risk in conventional investment theory. Risk has been taken to be volatility, but there are also various types of volatility. Portfolio management theory took the extent of deviation from the regression curve (something akin to the past average) to be volatility, but this is a mistake. Therefore, the efficient portfolio is also a mistake, so it has no meaning.Volatility that is the extent of deviation from the regression curve is a substitute that is both a risk and an opportunity.The assumptions for the theory are also unrealistic. It assumes that “all investors make the same forecast.” If that were the case, transactions would not take place (there would be no market). This is impossible. You would understand there is no way a theory founded on such impossible assumptions can be used in the real world.In this paper, risk has been correctly redefined, and investors are taken to make different forecasts based on realistic assumptions. So, what happens to investment theory? That is the theme of this paper. Please read the paper for specific details.Investors, no doubt, believe that investment theory and actual investment are different. Standard theory is closer to the sense of investors. (This is only natural when there are realistic assumptions).In addition, criticisms of Kahneman’s prospect theory are also provided, as they relate to both investment theory and investment methods. A theory (related to risk) separate from prospect theory is derived from the outcomes of the experiments conducted by Kahneman. This is more important than prospect theory and is also reflected in a new theory and investment strategies. Introduction to the ContentsPart 1. Standard Theory for Stock Investment - Theory Compilation5Chapter 1. Overview of Standard Theory6Chapter 2. Forecast Theory9 1. Features of forecasts10 2. Forecast methodology12 3. Relationship between forecast and return14Chapter 3. Reasoning About Risk17 1. Definition of risk18 2. Features of risk18 3. Relationship between risk and return23 4. Types of risk factors26Chapter 4. Investors29 1. Investment behavior30 2. What is a capable investor?33 3. Investor types34 4. Role of investors35 5. Evaluation of investors35Chapter 5. Stock35 1. Share price analysis37 2. Corporate analysis40Part 2. Standard Stock Investment Theory - Investment Strategy Compilation43Chapter 1. Investment Strategy Significance and Assumptions45Chapter 2. Basic Investment Behavior47 1. Investment ability48 2. Opportunities for return48 3. Taking risk (investing)51Chapter 3. Investment Methods56Part 3. Supplementary Information67Chapter 1. Human Behavioral Principles and Social and Economic Systems68 1. Human behavioral principles69 2. Human social and economic systems75Chapter 2. Criticisms of Prospect Theory811. What is prospect theory?822. Summary of prospect theory verification823. Specific verification84