(1) The essence of risk is uncertainty;
(2) Risk exists objectively;
(3) Risk is something people hate and don't want to happen. In their book Risk Management and Insurance, Arthur Williams Jr and Richard M. Hans of the United States define risk as "the difference between those possible outcomes in a specific situation and in a specific time. If there is only one result, the difference is zero and the risk is zero. If there are multiple possible outcomes, there are risks. The greater the difference, the greater the risk. " 192 1 American economist knight further elaborated the meaning of risk in his book Risk, Uncertainty and Profit. He thinks that risk is not general uncertainty, but "measurable uncertainty", and clearly points out that both actual risk and future risk in economic life can be measured and measured by mathematical statistical analysis. Knight's point of view laid the foundation for later risk assessment and measurement theory. After 1970s, the exchange rate risk caused by the collapse of the Bretton Woods system has aroused people's concern about the financial risk of enterprises. Although enterprise financial risk management should be an important part of risk management, the development of financial risk management has not attracted the attention of management and economics since 1980s. With the passage of time, financial risk management has finally attracted the attention of the industry in the American Institute of Risk Management and Insurance from 65438 to 0998. Stephen, then president of the American Institute of Risk Management and Insurance, pointed out in his university speech: "The study of risk management and insurance should shift from pure risk to investment risk, and from personal and property risk management to financial risk management." The international research on financial risk management can be traced back to 1950s, when three famous American economists, Kyle Weitz, william sharpe and Miller, made in-depth research on financial risk management. As early as 1952, Kyle Weitz published the article "Portfolio Selection" in Finance magazine. This article uses the expected return and mean square error of risky assets to study the return and risk of portfolio, which is regarded as the starting point of modern portfolio theory by academic circles. He put forward the concept of portfolio efficiency boundary, that is, under the same risk, the portfolio income on the efficiency boundary is the highest; Under the same income, the portfolio with efficiency boundary is the most risky. In the early 1960s, william sharpe inherited and developed the theory of Kyle Weitz, which is the famous capital asset pricing model. His theoretical conclusion is that the risk of a stock includes systematic risk and non-systematic risk, which can be eliminated by decentralization. In order to take risks, investors must be compensated. The greater the risk, the greater the required rate of return. He provided a method to calculate the systematic risk of stock and a model to calculate the expected return of stock through the systematic risk-capital asset pricing model.