We examine the quantitative impact of policy-induced changes in firms’ innovative investment on growth in aggregate productivity and output in a model that nests several of the canonical models. We isolate two statistics, the impact elasticity of aggregate productivity growth with respect to aggregate innovative investment and the degree of intertemporal knowledge spillovers in research, that shape the model’s predicted dynamic response to a change in the innovation intensity of the economy. Given measures of these statistics, there is only modest scope for increasing aggregate productivity and output over a 20-year horizon with uniform innovation subsidies to firms’ investments in innovation of a reasonable magnitude, but the welfare gains may be substantial.

We present a general equilibrium model of the decisions of firms to innovate and to engage in international trade. We use the model to analyze the impact of a reduction in international trade costs on firms ’ process and product innovative activity. We first show analytically that if all firms export with equal intensity, then a reduction in international trade costs has no impact at all, in steady-state, on firms ’ investments in process innovation. We then show that if only a subset of firms export, a decline in marginal trade costs raises process innovation in exporting firms relative to that of non-exporting firms. This reallocation of process innovation reinforces existing patterns of comparative advantage, and leads to an amplified response of trade volumes and output over time. In a quantitative version of the model, we show that the increase in process innovation is largely offset by a decline in product innovation. We find that, even if process innovation is very elastic and leads to a large dynamic response of trade, output, consumption, and the firm size distribution, the dynamic welfare gains are very similar to those in a model with inelastic process innovation.

Manufacturing plants have a clear life cycle: they are born small, grow substantially with age, and eventually die. Economists have long thought that this life cycle is driven by organization capital, the accumulation of plant‐specific knowledge. The location of plants in the life cycle determines the size of the payments, or organization rents, plant owners receive from organization capital. These payments are compensation for the interest cost to plant owners of waiting for their plants to grow. We use a quantitative growth model of the life cycle of plants, along with U.S. data, to infer the overall size of these payments.

We analyze the effects of money injections on interest rates and exchange rates when agents must pay a Baumol‐Tobin‐style fixed cost to exchange bonds and money. Asset markets are endogenously segmented because this fixed cost leads agents to trade bonds and money infrequently. When the government injects money through an open market operation, only those agents that are currently trading absorb these injections. Through their impact on these agents’ consumption, these money injections affect real interest rates and real exchange rates. The model generates the observed negative relation between expected inflation and real interest rates as well as persistent liquidity effects in interest rates and volatile and persistent exchange rates.