In the past several decades, the U.S. economy has witnessed a number of striking trends that indicate a rising market concentration and a slowdown in business dynamism. In this paper, we make an attempt to understand potential common forces behind these empirical regularities through the lens of a micro-founded general equilibrium model of endogenous firm dynamics. Importantly, the theoretical model captures the strategic behavior between competing firms, its effect on their innovation decisions, and the resulting "best versus the rest" dynamics. We focus on multiple potential mechanisms that can potentially drive the observed changes and use the calibrated model to assess the relative importance of these channels with particular attention to the implied transitional dynamics. Our results highlight the dominant role of a decline in the intensity of knowledge diffusion from the frontier firms to the laggard ones in explaining the observed shifts. We conclude by presenting new evidence that corroborates a declining knowledge diffusion in the economy. We document a higher concentration of patenting in the hands of firms with the largest stock and a changing nature of patents, especially in the post-2000 period, which suggests a heavy use of intellectual property protection by market leaders to limit the diffusion of knowledge. These findings present a potential avenue for future research on the drivers of declining knowledge diffusion.

In this paper, we review the literature on declining business dynamism and its implications in the United States and propose a unifying theory to analyze the symptoms and the potential causes of this decline. We first highlight 10 pronounced stylized facts related to declining business dynamism documented in the literature and discuss some of the existing attempts to explain them. We then describe a theoretical framework of endogenous markups, innovation, and competition that can potentially speak to all of these facts jointly. We next explore some theoretical predictions of this framework, which are shaped by two interacting forces: a composition effect that determines the market concentration and an incentive effect that determines how firms respond to a given concentration in the economy. The results highlight that a decline in knowledge diffusion between frontier and laggard firms could be a significant driver of empirical trends observed in the data. This study emphasizes the potential of growth theory for the analysis of factors behind declining business dynamism and the need for further investigation in this direction.

How do import tariffs and R&D subsidies help domestic firms compete globally? How do these policies affect aggregate growth and economic welfare? To answer these questions, we build a dynamic general equilibrium growth model where firm innovation endogenously determines the dynamics of technology, and, therefore, market leadership and trade flows, in a world with two large open economies at different stages of development. Firms' R&D decisions are driven by (i) the defensive innovation motive, (ii) the expansionary innovation motive, and (iii) technology spillovers. The theoretical investigation illustrates that, statically, globalization (defined as reduced trade barriers) has ambiguous effects on welfare, while, dynamically, intensified globalization boosts domestic innovation through induced international competition. Accounting for transitional dynamics, we use our model for policy evaluation and compute optimal policies over different time horizons. The model suggests that the introduction of the Research and Experimentation Tax Credit in 1981 proves to be an effective policy response to foreign competition, generating substantial welfare gains in the long run. A counterfactual exercise shows that increasing tariffs as an alternative policy response improves domestic welfare only when the policymaker cares about the very short run, and only when introduced unilaterally. Tariffs generate large welfare losses in the medium and long run, or when there is retaliation by the foreign economy. Protectionist measures generate large dynamic losses by distorting the impact of openness on innovation incentives and productivity growth. Finally, our model predicts that a more globalized world entails less government intervention, thanks to innovation-stimulating effects of intensified international competition.

In this paper, we review the literature on declining business dynamism and its implications in the United States and propose a unifying theory to analyze the symptoms and the potential causes of this decline. We first highlight 10 pronounced stylized facts related to declining business dynamism documented in the literature and discuss some of the existing attempts to explain them. We then describe a theoretical framework of endogenous markups, innovation, and competition that can potentially speak to all of these facts jointly. We next explore some theoretical predictions of this framework, which are shaped by two interacting forces: a composition effect that determines the market concentration and an incentive effect that determines how firms respond to a given concentration in the economy. The results highlight that a decline in knowledge diffusion between frontier and laggard firms could be a significant driver of empirical trends observed in the data. This study emphasizes the potential of growth theory for the analysis of factors behind declining business dynamism and the need for further investigation in this direction. (JEL D33, E25, J24, L13, O33, O34)