Investing is more intelligent the more it is based on rules and procedures. At Raven Capital our main rule is to invest in opportunities that offer a Margin of Safety. The Margin of Safety is essential when making an investment. The Margin of Safety prevents and limits potential losses that can occur in a portfolio. If there is a Margin of Safety on all purchases made in a portfolio, the probability of a favorable outcome under "normal conditions" is quite high. If in addition these purchases are made over a long period of time, the prices paid for the assets in the portfolio have an even greater Margin of Safety embedded in them.