The Global Market Index (GMI) that’s frequently cited on these digital pages is a robust benchmark for the simple reason that it holds all the major asset classes in market-value weights and shuns rebalancing. In other words, GMI is a measure of global beta that’s available to anyone and everyone, at low cost and in a forecast-free framework. In short, a monkey could replicate GMI. As it turns out, a monkey can do quite well through time with this strategy. Nonetheless, readers periodically ask why GMI’s relatively short historical track record is a reliable guide to the future? Great question, and one that deserves more than a trivial answer.