Structural Change in the Investment Function

Investment is an important contributor to aggregate demand, and it is critical to fostering productivity and fueling innovation. Absent from the existing literature on business investment is the recognition that the determinants of investment have changed over time in fundamental ways. Using quarterly data from 1953–2016, we estimate an augmented accelerator function of U.S. business investment and present evidence of a structural change in the year 2000. Our findings suggest that while the accelerator and crowding-out effects have weakened over time, the sensitivity of investment growth to cost of capital, risk spread, cash flows, and economic policy uncertainty have increased in recent years. In light of these results, we highlight and evaluate several recent hypotheses regarding structural changes in the U.S. economy. In particular, we argue that our results are not consistent with the secular stagnation hypothesis, but are more closely connected to long-term trends in demographics, market concentration, financialization, and the inter-industry reconfiguration of firms away from traditional manufacturing.