Almost everyone in risk management knew that quantitative methods – like those used to measure and forecast exposures, value complex derivatives and assign credit ratings – did not work and could provide undue comfort by hiding risks. Few people would agree that the illusion of knowledge is a good thing. Almost everyone would accept that the failure in 1998 of Long Term Capital Management discredited the quantitative methods of the Nobel economists involved with it (Robert Merton and Myron Scholes) and their school of thought called “modern finance”. LTCM was just one in hundreds of such episodes.
Yet a method heavily grounded on those same quantitative and theoretical principles, called Value at Risk, continued to be widely used. It was this that was to blame for the crisis. Listening to us, risk management practitioners would often agree on every point. But they elected to take part in the system and to play bystanders. They tried to explain away their decision to partake in the vast diffusion of responsibility: “Lehman Brothers and Morgan Stanley use the model” or “it is on the CFA exam” or, the most potent argument, “modern finance and portfolio theory got Nobels”. Indeed, the same Nobel economists who helped blow up the system at least once, Professors Scholes and Merton, could be seen lecturing us on risk management, to the ire of one of the authors of this article. Most poignantly, the police itself may have participated in the murder. The regulators were using the same arguments. They, too, were responsible.
In an earlier post I wrote that the risk models seemed to have worked but were ignored. Taleb believes they didn't even work. He knows these models better than I do, so perhaps he is right. While we're on the subject I would recommend The Black Swan, just be forewarned that Taleb's ego consistently interferes with the material. Arrogance aside, the ideas are important.
On the same theme, here is Vikram Pandit, CEO of Citigroup on risk management: