Over the past 15 years, the global economy has operated under two different growth models. Between 1999 and 2007, the growth model operated through ever larger trade imbalances between emerging market and commodity exporting countries – who ran larger and larger surpluses – and a group of rich countries – first and foremost the U.S. – who ran larger and larger trade deficits. Global imbalances were then seen as a problem by some, but they were really a symptom of the global geographic distribution of aggregate supply and demand, with excess supply in the high-saving emerging market countries and excess demand in some low-saving rich countries (and with energy exporting countries doing quite well as they exported to both). These supply-demand and saving-investment imbalances generated huge international capital flows that were sufficient to bring global demand into line with abundant global supply of goods at something approximating the full employment of global resources. ... That growth model obviously broke down in the global financial crisis years of 2007–2009 as global imbalances shrunk in line with global aggregate demand. From 2009–2014, the global economy has operated under stimulus from “nontraditional” monetary policies that pushed policy rates to zero and ballooned central bank balance sheets through massive “chunks” of quantitative easing. Also, the global policymakers “went Keynesian” for a couple of years during and following the crisis by delivering a large dose of fiscal stimulus. The good news is that, as a result, the global economy avoided depression and deflation. But that’s all they did or could reasonably do. The reality is that now, five years after the global financial crisis, average growth in the global economy is modest and the level of global GDP remains below potential. The global economy has not as of today found a growth model that can generate and distribute global aggregate demand sufficient to absorb bountiful global aggregate supply. Unless and until it does, we will be operating in a multi-speed world with countries converging to historically modest trend rates of potential growth with low inflation. 0% neutral real policy rates for many developed and some developing countries will likely be the investment outcome.