Quant Risk Management Models Under Fire

For those interested in some of the more technical issues that led to the financial crisis, the New York Times Magazine has a worthwhile feature piece this week on how VaR, a core risk model used by money managers and investment banks has proven disastrous in predicting bad markets. Or so some people think. Below are contrasting views.


David Einhorn, who founded Greenlight Capital, a prominent hedge fund, wrote not long ago that VaR was “relatively useless as a risk-management tool and potentially catastrophic when its use creates a false sense of security among senior managers and watchdogs. This is like an air bag that works all the time, except when you have a car accident.” Nassim Nicholas Taleb, the best-selling author of The Black Swan, has crusaded against VaR for more than a decade. He calls it, flatly, “a fraud.”


“VaR WAS INEVITABLE,” Gregg Berman of RiskMetrics said when I went to see him a few days later. He didn’t sound like an intellectual charlatan. His explanation of the utility of VaR — and its limitations — made a certain undeniable sense. He did, however, sound like somebody who was completely taken aback by the amount of blame placed on risk modeling since the financial crisis began.

“Obviously, we are big proponents of risk models,” he said. “But a computer does not do risk modeling. People do it. And people got overzealous and they stopped being careful. They took on too much leverage. And whether they had models that missed that, or they weren’t paying enough attention, I don’t know. But I do think that this was much more a failure of management than of risk management. I think blaming models for this would be very unfortunate because you are placing blame on a mathematical equation. You can’t blame math,” he added with some exasperation.