Zitat des Tages von Harry Markowitz:
I would never be 100 percent in stocks or 100 percent in bonds or cash.
I was born in Chicago in 1927, the only child of Morris and Mildred Markowitz, who owned a small grocery store. We lived in a nice apartment, always had enough to eat, and I had my own room. I never was aware of the Great Depression.
Diversifying sufficiently among uncorrelated risks can reduce portfolio risk toward zero. But financial engineers should know that's not true of a portfolio of correlated risks.
During the 1950s, I decided, as did many others, that many practical problems were beyond analytic solution and that simulation techniques were required. At RAND, I participated in the building of large logistics simulation models; at General Electric, I helped build models of manufacturing plants.
Portfolio theory, as used by most financial planners, recommends that you diversify with a balance of stocks and bonds and cash that's suitable to your risk tolerance.