"Wednesday is the type of day people will remember in quant-land for a very long time," Rothman told the Wall Street Journal "Events that models only predicted would happen once in 10,000 years happened every day for three days." http://www.dealbreaker.com/2007/08/quant_bloodbath_revisited_a_pr.php
"The pressure to generate returns in what was a low-return environment has without doubt caused investors to go into less liquid spaces. In the past those less liquid parts of the credit markets had mostly long-term investors in them. Now they are mostly short-term investors, who are facing a liquidity crisis."
Some of the earliest quantitative investment methods included the successful identification by Benoit Mandelbrot, the Yale mathematics professor, of patterns in cotton prices in the 1960s, writes Anuj Gangahar. FT repeated in http://www.msnbc.msn.com/id/20267284/
Nassim Taleb:
emphatically rejected the [central limit theorem], and the entire "Gaussian" approach as applicable to social and economic reality. . . . He pointed out ... that the fractal approach, which does not give precise probabilities, is much more applicable to social reality because it does not arbitrarily dismiss inconvenient events as "outliers." For example, according to Taleb, the Crash of 1987, the proverbial Black Swan to Gaussians, "is not an outlier if you use a fractal with an exponent of 3." (In the Gaussian world the Crash of 1987 was 20 standard deviations from the mean, an episode that would occur "every several billion lifetimes of the universe.") Taleb went on to argue that Mandelbrot's fractals allow us to account for a few Black Swans, although by no means all, and transform them into Gray Swans or "known unknowns." Taleb also produced a startling graph showing that in the last 50 years the ten most extreme days in the financial markets represent half the returns. And yet these Black Swans are dismissed by Gaussians. Taleb concluded that those using sigmas (standard deviations) as a measure of risk and randomness in the world of finance were practicing "phony mathematics" and were "charlatans." http://organizationsandmarkets.com/2006/11/15/randomness-and-the-black-swan/