We analyze private fixed investment in the U.S. over the past 30 years. We show that investment is weak relative to measures of profitability and valuation – particularly Tobin's Q, and that this weakness starts in the early 2000's. There are two broad categories of explanations: theories that...

We study the evolution of profits, investment and market shares in US industries over the past 40 years. During the 1990's, and at low levels of initial concentration, we find evidence of efficient concentration driven by tougher price competition, intangible investment, and increasing...