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A Hedge-Fund Mystery

Why did a number of equity hedge funds suffer big losses in August 2007 — and what do those losses say about systemic risk?

Last August was a bad month for the hedge-fund industry. According to fund tracker Barclay Hedge Ltd., about 75 percent of the 2,600 or so hedge funds that reported results for the month showed a loss, of about 1.4 percent on average. The week of August 6 was particularly cruel to quantitative equity hedge funds. A number of prominent “quants,” managed by the likes of Goldman Sachs and Renaissance Technologies, suffered losses reportedly ranging from 5 percent to more than 30 percent.

What happened to the quants? The question forms the title of a recent article by two researchers from the Massachusetts Institute of Technology — Amir E. Khandani, a graduate student; and Andrew W. Lo, a well-known professor of finance at MIT’s Sloan School of Management and founder and chief scientific officer of AlphaSimplex Group, a hedge fund. Like a pair of detectives, working with indirect clues (hedge funds are famously secretive) and an investment simulation, Khandani and Lo set out to discover why the quants lost so much money.

Their conclusions, they stress, must be regarded as speculative, since the people who know what happened — the hedge-fund managers — aren’t talking. Still, Khandani and Lo’s diagnosis is entirely plausible, and raises disturbing questions about systemic risk in the hedge-fund industry.

Suspecting a Liquidation

Systemic risk here refers to the possibility that huge, correlated losses can rapidly occur among funds, as in a banking panic. Such correlated losses may be triggered by a single event — such as the near-collapse in August 1998 of the hedge fund Long-Term Capital Management (LTCM), which briefly menaced the stability of the global financial system.

Did a similar event spark the hedge-fund losses last August? Khandani and Lo believe so. Sometime on August 7 or 8, they theorize, one or more sizable quantitative equity market-neutral portfolios were suddenly unwound. The liquidation had a significant, if temporary, impact on equity prices. That caused other quants — many of them equity long/short funds, which hold stocks in both long and short positions — to cut their own losses and sell. What Khandani and Lo call the “perfect financial storm” ended on August 10, when the liquidations ceased and returns climbed sharply.

The steep drop and rebound, they note, were consistent with a “liquidity event” such as a portfolio sell-off. To test their theory, Khandani and Lo simulated an equity long/short strategy for the week of August 6, leveraged approximately 8 to 1. Sure enough, a fund using the test strategy would have lost more than 27 percent of its assets between August 7 and 9, and gained about 24 percent on August 10.

As for why the losses were so large, the researchers point out that investors have poured money into equity long/short funds over the past decade, making them the most popular hedge-fund category. At the same time, the profitability of the strategy has declined, due to increasing competition and technological advances. In order to maintain their accustomed level of returns, therefore, long/short funds have had to increase leverage.

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