Michael Lewis, an awesomely interesting writer, offered readers of March’s Portfolio Magazine an overly bearish appraisal of the Black-Scholes options pricing model.
This may not, of course, be Lewis’ fault. Portfolio is published by Conde Nast, notorious for yellowing-up its journalism to maximize the shock/sex/scandal factor. How Conde Nast sexed up Wired Magazine to the point of near-unreadability is a sore spot with many readers to this day who say the magazine was “Conde Nastified.”
The story, titled “Inside Wall Street’s Black Hole,” (natch) posits this: The credit crunch ousted bank executives and average Joe Homeowner alike because everybody was mis-pricing their downside protections. Wall Street broker/dealers used Black-Scholes, which provides a framework for pricing options, to justify extending credit to would-be homeowners. But the famous formula doesn’t take into account the possibility of cataclysmic downturns. When the downturn happened, the predictive model didn’t hold up. Therefore, Black-Scholes screwed everybody.
Lewis then goes on to “prove” the point by including quotes from one interview and by paraphrasing much of Nassim Nicholas Taleb’s work (for this feat of journalism he gets paid an ungodly amount per word).
The thesis belies a surprising amount of naivitae. It’s like getting lost on the island of la Grande Jatte and blaming Georges-Pierre Seurat for not giving you an accurate map.
Lewis would do well to remember that a financial theory is just that. It is not a universal law. Newton’s theories of motion start to fall apart when you approach the speed of light, so should anyone be surprised when Black-Scholes starts to break down as the economy fluctuates wildly?
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When the Portfolio cover-line promised me “The Formula that Wrecked Wall Street,” a very different formula immediately jumped to mind: 2 and 20.
That’s the compensation formula used by most hedge funds. It works like this: A hedge fund raises $100 million from private investors, university endowments, large banks and the like. The managers get 2% of that a year, regardless of performance. If they make a profit on their investing operations, say the portfolio gains 10% to $110 million, they get 20% of the profit, or $2 million.
It’s not a bad deal if you can get it: The hedge fund manager walks away with $4 million in income for getting about the market rate of return.
But what’s really deleterious to Wall Street, and general macroeconomic stability, is what happens in year two.
Let’s say the hedge fund manager has a bad year and the portfolio loses 10% of its value (It’s now worth $99 million). The manager still gets $2 million for his “management fee,” but doesn’t take home any bonus pay.
It doesn’t sound like that would have a negative effect, but it does. That compensation structure creates the incentive for the hedge fund manager to take wild risks, literally gamble it all for a shot at a bigger management fee because there’s no downside to poor performance.
If the manager loses all the fund’s money after five years, he or she still walks away with $10 million in fees. And since there’s so little visibility into the performance of hedge funds, there’s little accountability. An unscrupulous hedge fund manager might easily be able to raise another fund. (Which is why public disclosure is important and why journalists serve a role in the new economy.)
So why not risk it all? Go for the one in a hundred chance you’ll get a 100x payoff. It’ll always be preferable to the one in two chance of a x/2 gain.
That’s a formula that’s wrecking Wall Street and probably scares the heck out of Ben Bernanke.