We develop an equilibrium model of firm dynamics with random search in the labor market where hiring firms exert recruiting effort by spending resources to fill vacancies faster. Consistent with microevidence, fast-growing firms invest more in recruiting activities and achieve higher job-filling rates. These hiring decisions of firms aggregate into an index of economy-wide recruiting intensity. We study how aggregate shocks transmit to recruiting intensity, and whether this channel can account for the dynamics of aggregate matching efficiency during the Great Recession. Productivity and financial shocks lead to sizable pro-cyclical fluctuations in matching efficiency through recruiting effort. Quantitatively, the main mechanism is that firms attain their employment targets by adjusting their recruiting effort in response to movements in labor market slackness.

We document how export quantities and prices evolve after entry to a market. Controlling for marginal cost, and taking account of selection on idiosyncratic demand, there are economically and statistically significant dynamics of quantities, but no dynamics of prices. To match these facts, we estimate a model where firms invest in customer base through non-price actions (e.g. marketing and advertising), and learn gradually about their idiosyncratic demand. The model matches quantity, price and exit moments. Parameter estimates imply costs of adjusting investment in customer base, and slow learning about demand, both of which generate sluggish responses of sales to shocks.

I propose an equilibrium menu cost model with a continuum of sectors, each consisting of strategically engaged firms. Compared to a model with monopolistically competitive sectors that is calibrated to the same data on good-level price flexibility, the dynamic duopoly model features a smaller inflation response to monetary shocks and output responses that are more than twice as large. The model also implies (i) four times larger welfare losses from nominal rigidities, (ii) smaller menu costs and idiosyncratic shocks are needed to match the data, (iii) a U-shaped relationship between market concentration and price flexibility, for which I find empirical support.

In all markets, firms go through a process of creative destruction: entry, random growth and exit. In many of these markets there are also regulations that restrict entry, possibly distorting this process. We study the public interest rationale for entry taxes in a general equilibrium model with free entry and exit of firms in which firm dynamics are driven by reputation concerns. In our model firms can produce high-quality output by making a costly but efficient initial unobservable investment. If buyers never learn about this investment, an extreme “lemons problem” develops, no firm invests, and the market shuts down. Learning introduces reputation incentives such that a fraction of entrants do invest. We show that, if the market operates with spot prices, entry taxes always enhance the role of reputation to induce investment, improving welfare despite the impact of these taxes on equilibrium prices and total production.