“If you put a gun to my head and asked me what my firm’s risk was, I would use VaR.” - said Richard Bookstaber, a hedge-fund risk manager. New York times has a long article on the role of VaR in risk management ( bugmenot for nytimes ) that includes the arguments on both the sides. Simply put Value At Risk , known as VaR, is a mathematical framework based on many underlying models that quantifies the risk into single dollar figure with 99% probability. Firm managers really like this number since they can measure individual trader's risk and the total risk of the firm. People such as Nassim Nicholas Taleb who are against VaR passionately argue that not being able to measure the impact of the last 1% could result into catastrophic losses under Black Swan events. He argues that people cannot predict and measure the risk using a model for the events that they have not seen in their lifetimes but the events that do occur in their lifetimes. Nassim is a person who hates ties, loves ...