A margin of safety is achieved when securities are purchased at prices sufficiently below underlying value to allow for human error, bad luck, or extreme volatility in a complex, unpredictable and rapidly changing world.
There are only a few things investors can do to counteract risk: diversify adequately, hedge when appropriate, and invest with a margin of safety. It is a precisely because we do not and cannot know all the risks of an investment that we strive to invest at a discount. The bargain element helps to provide a cushion for when things go wrong.
Investors frequently benefit from making decisions with less than perfect knowledge and are well rewarded for bearing the risk of uncertainty. The time other investors spend delving into the last unanswered detail may cost them the chance to buy into situations at prices so low they offer a margin of safety despite the incomplete information
