In Chapter 20 of The Intelligent Investor, Benjamin Graham covers the ” ‘Margin of Safety’ as the Central Concept of Investment.” This big idea or motto is the “secret of sound investment” distilled to three words.
Graham says “the function of the margin of safety is, in essence, that of rendering unnecessary an accurate estimate of the future.” When considering whether an investment carries a favorable margin of safety, calculations should be based on present circumstances, not overly optimistic or hoped-for future situations.
As I delve into this chapter, I learn that though the margin-of-safety principle is one of the main things, it’s not the only thing relevant to intelligent investing. Its companion is diversification. In addition, I discover that real-life adherence to safety margins isn’t simple or always achievable.
Still, the concept is important and mathematical framework, crucial to the task of selecting securities and building a portfolio.