VaR Enough? Market turbulence tests the limits of Value at Risk

By Irwin Speizer

When an investment bank that is supposed to know better loses billions of dollars betting on subprime mortgages, you have to wonder what happened to the concept of risk management. “You can’t rely on VaR as your only metric,” says Leslie Rahl, president and founder of New York–based Capital Market Risk Advisors. “We recommend people use three to five different metrics. It’s like a doctor ordering an X ray, an MRI and a CAT scan — they all tell you slightly different things.”

A veteran of 35 years in the financial industry and a financial engineering pioneer, Rahl ran the derivatives business at Citibank in the 1980s before establishing her consulting firm in 1991. She preaches the importance of rigorous risk analysis and testing to cope with the impact of the types of investments she peddled in her earlier role.

Rahl recommends applying stress tests to see how a portfolio would react to sharp drops, market shifts, unusual situations or changes in underlying assumptions. Stress-testing models, which are included in risk systems, can reveal weaknesses that a simple VaR test misses. But Rahl says too many financial firms continue to rely mostly on VaR. Back in April 2000, Rahl’s firm conducted a survey of risk practices and found that 45 percent of financial firms, including hedge funds, were not using stress tests at all. Although she hasn’t updated the survey, she says she has noticed only a slight improvement since then.

 “In risk management only about a third is quantitative,” Rahl says. “A third is still a big part of the puzzle, so it is quite valuable.”

The remaining two thirds of the puzzle is where good risk managers earn their money. Ultimately, an accurate forecast depends on knowledge, experience and chutzpah.

“It has nothing to do with the computer,” Rahl says. “It has to do with wisdom and experience.”

And perhaps a bit of luck.

June 2008