Knowledge that Transforms

Recent literature has shown that the fraction of liquidity-constrained households in the population critically determines the mix of transmission channels of monetary policy. In this article, we bring a different but important dimension of heterogeneity to the forefront: stock market participation. We show that the stock market participation rate not only shapes the mix of policy channels but also heavily affects the aggregate responses. This happens as direct rebalancing effects and indirect equilibrium effects into investment are both increasing in the number of stock market participants, reinforcing each other. We show this in a quantitative New Keynesian model designed to account for the population share of stock market participants, their position in the income and wealth distribution, and their saving rates. The model implies that, as stock market participation has increased since the 1980s, the power of monetary policy on the real economy has strengthened considerably.

In a broad class of sticky-price models, the non-neutrality of nominal shocks is captured by a simple sufficient statistic: the ratio of the kurtosis of the price change distribution over the frequency of price changes. We test the sufficient statistic proposition using data for a large sample of products representative of the French economy. We first extend the theory to allow for empirically relevant monetary shocks with a transitory predictable component. We then use the microdata to measure kurtosis and frequency for about 120 producer price indices industries and 220 consumer price indices categories. We use a Factor-Augmented Vector Autoregressive (FAVAR) model to measure the industries’ response to monetary shocks, under alternative identification schemes. The estimated degree of non-neutrality correlates with the kurtosis and the frequency consistently with the predictions of the theory. Several robustness checks are discussed.

We consider a procurement auction for the provision of a basic service to which an add-on must later be appended. Potential providers are symmetric, have private information on their cost for the basic service and the winning firm must also implement the add-on. To finance value-enhancing activities related to the add-on, this firm may need extra funding by outside financiers. Nonverifiable effort related to these activities creates a moral hazard problem which makes the firm’s payoff function for the second period concave in returns over the relevant range. Concavity has two effects. First, it makes it more attractive to backload payments to facilitate information revelation. Second, uncertainty on the cost of the add-on introduces a background risk which requires a risk premium. In this context, we characterize the optimal intertemporal structure of payments to the winning firm, equilibrium bidding behaviour and reserve prices for a first-price auction.

We study non-monetary markets where objects that arrive over time are allocated to unit-demand agents with private types, such as in the allocation of public housing or deceased-donor organs. An agent’s value for an object is supermodular in her type and the object quality, and her payoff is her value minus her waiting cost. The social planner’s objective is a weighted sum of allocative efficiency (i.e. the sum of values) and welfare (i.e. the sum of payoffs). We identify optimal mechanisms in the class of direct-revelation mechanisms. When the social planner can design the information disclosed to the agents about the objects, the optimal mechanism has a simple implementation: a first-come first-served waitlist with deferrals. In this implementation, the object qualities are partitioned into intervals; only the interval containing the object quality is disclosed to agents. When the planner places a higher weight on welfare, optimal disclosure policies become coarser.

We measure the distribution of welfare losses from non-competitive behaviour in the U.S. credit card industry during the 1970s and 1980s. The early credit card industry was characterized by regional monopolies. Ensuing legal decisions led to competitive reforms that resulted in greater, but still limited, oligopolistic competition. We measure the distributional consequences of these reforms by developing and estimating a heterogeneous agent, defaultable debt framework with oligopolistic lenders. The transition from monopoly to oligopolistic competition yields welfare gains equivalent to a one-time transfer worth $3,600 (in 2016 dollars) for the bottom decile of earners (roughly 50% of their annual income) versus $1,200 for the top decile of earners. As the credit market expands, low-income households benefit more since they rely disproportionately on credit to smooth consumption. Greater competition also explains rising bankruptcies, chargeoffs, and credit to income ratios. Lastly, we bound the welfare gains from competition by computing a perfectly competitive benchmark. Aggregate welfare gains are 40% larger from perfect competition but distributed similarly to oligopolistic competition.

We study how firms target and influence expert intermediaries. In our context, pharmaceutical manufacturers provide payments to physicians during promotional interactions. We develop an identification strategy based on plausibly exogenous variation in payments driven by differential exposure to spillovers from AMC CoI policies. Using a case study of an important class of cardiovascular drugs, we estimate heterogeneous effects of payments on prescribing, with firms targeting highly responsive physicians. We also develop a model of supply and demand, which allows us to quantify how oligopoly prices reduce drug prescribing, and how payments move prescribing closer to the optimal level, but at great financial cost. In our estimated model, whether consumers are harmed by payments depends on whether there is substantial under-prescribing due to behavioural or other frictions. In a final exercise, we calibrate such frictions using clinical data and estimate that payments benefit consumers in this case study.

This study presents a new economic perspective on state-building based on a case study in the Democratic Republic of the Congo’s hinterland. We explore the implications for the state of considering rebels as stationary bandits. When the state, through a military operation, made it impossible for rebels to levy taxes, it inadvertently encouraged them to plunder the assets of the very citizens they previously preferred to tax. When it negotiated with rebels instead, this effect was absent, but negotiating compromised the state’s legitimacy and prompted the emergence of new rebels. The findings suggest that attempting to increase taxation by a weak state in the hinterland could come at the expense of safety in the medium term and of the integrity of the state in the long term.

Regulations to design private yet publicly sponsored health insurance markets are increasingly adopted in many OECD countries. Here I combine data and economic theory to analyse the interaction between insurers’ competition and the design of premium subsidies in determining equilibrium outcomes. My empirical model includes adverse selection, rich heterogeneity in preferences for vertically and horizontally differentiated plans and accommodates alternative assumptions on pricing conduct. In the context of the Affordable Care Act in the U.S., I estimate the joint distribution of preferences and expected cost using Californian administrative records on 3.4 million plan choices between 2014 and 2017, combined with plan and survey data on medical claims. An empirical horse race between conduct assumptions favours oligopoly pricing over perfect competition. Considering alternative subsidy designs shows that, in equilibrium, shifting subsidy generosity toward the “young invincibles” would lower premiums for all enrolees while increasing enrolment and profits.

We develop a framework to understand pre-employment credit screening as a signal from credit markets that alleviates adverse selection in labour markets. In our theory, people differ in both their propensity to default on debt and the profits they create for firms that employ them; in our calibrated economy, highly productive workers have a low default probability. This leads firms to create more jobs for those with good credit, which creates a poverty trap: an unemployed worker with poor credit has a low job finding rate, but cannot improve her credit without a job. This manifests as an endogenous loss in present-discounted wages that is typically taken as exogenous in quantitative models of consumer default. Banning employer credit checks eliminates the poverty trap, but pools job seekers and reduces matching efficiency: average unemployment duration rises by 2 days for high productivity workers and falls by 13 days for low-productivity workers.

THANK is a tractable heterogeneous-agent New-Keynesian model that captures analytically core micro-heterogeneity channels of quantitative-HANK: cyclical inequality and risk; self-insurance, precautionary saving, and realistic intertemporal marginal propensities to consume. I use it to elucidate key transmission mechanisms and dynamic properties of HANK models. Countercyclical inequality yields aggregate-demand amplification and makes determinacy with Taylor rules more stringent; but solving the forward guidance puzzle requires procyclical inequality: a Catch-22. Solutions include combining inequality with a distinct risk channel, with compensating cyclicalities; I provide evidence that disposable income inequality was procyclical in the last two, Great and COVID recessions, while risk is countercyclical. Alternative policy rules also solve the Catch-22, e.g. price-level-targeting or, in the model version with liquidity, setting nominal public debt. Optimal policy with heterogeneity features a novel inequality-stabilization motive generating higher inflation volatility—but is unaffected by risk, insofar as the target efficient equilibrium entails no inequality.