September 22nd, 2011, 8:52 pm
Well my interaction with Global Alpha has only been tangental, so take what I say with a grain of salt. But...Global Alpha's stat arb models were very macro-ish focused. A lot of their alpha traditionally came from country allocation in addition to security selection. Even on the security selection side they had a very fundamental focus, e.g. balance sheet, earnings, industry to generate their factor models. Starting in 2007 and especially in 2008 these types of models broke down. The stat arb that survived had a much more "numerical" focus. The main difference between the two is that GSAM style stat-arb is more longer term oriented, after all macro and fundamental data gets updated on the order of months. Numerical alpha models can more easily be adjusted at any horizon as long as you have market data at that resolution. There are a couple of reasons for why their style did so poorly. The first would probably be the high-frequency revolution. A lot of the stat-arb alpha simply moved to shorter horizons. Global Alpha's models just didn't work at this level. The second would be the rapidly changing relationships during the period. Market factors rapidly shifted in short periods. In 2008 the second largest factor after market beta was pretty much financials vs non-financials, in summer 2010 and 2011 it quickly became euro-zone vs non euro-zone, at other periods momentum became a huge factor, etc. Correlation rapidly went to 1, then came down just as fast. Global Alpha has always done poorly during regime changes, and between 2008 and today there have been a lot. With numerical alpha you can more quickly invalidate your models, detect regime changes and refit, because you have more data points. The question would be why then didn't they see the writing on the wall and adapt. I think a number of reasons. First would be because they had a large asset base. The problem with moving to shorter term models is that it lowers your trading capacity. At one point they were $10bn, and I think their business goal was always to get back to that asset level. The fundamental/macro stuff takes a lot more researchers, so they couldn't support their headcount with a smaller asset base. One could argue they should have shrank their operations and asset base and possibly converted to prop trading where they could net all their pnl instead of just 2/20. But hindsight is 20/20.The second thing is that Global Alpha was a very academic environment. They had a long history of publishing their results (which arguably was the beginning of their downfall as people replicated them and took their alpha). You don't see any published papers coming out of RenTech. The numerical alpha stuff is simply much less interesting from an academic viewpoint, and most people there had backgrounds more in fitting macroeconomic relationships, rather than crunching huge datasets in a HPC. They probably figured their comparative advantage laid in that style of stat arb.