Knowledge that Transforms

We use a sufficient statistic approach to quantify the general equilibrium effects of population aging on the returns to wealth, wealth accumulation, and global imbalances. Combining population forecasts with household survey data from 25 countries, we measure the compositional effect of aging: how a changing age distribution affects wealth-to-GDP, holding the age profiles of wealth and labor income fixed. In a baseline overlapping generations model this statistic, in conjunction with cross-sectional information and two standard macro parameters, pins down general equilibrium outcomes. Since the compositional effect is positive, large, and heterogeneous across countries, our model predicts that population aging will lower returns to wealth, increase wealth-to-GDP ratios, and widen global imbalances through the twenty-first century. These conclusions extend to a richer model in which bequests, individual savings, and the tax-and-transfer system all respond to demographic change.

Over the past four decades, the U.S. economy has seen a decline in the share of young firms alongside a rise in the profit share of GDP. This paper explores how population aging contributes to these twin trends through a demand-side channel. The core hypothesis is that younger households exhibit lower consumer inertia—a tendency to stick with previously chosen products—than older households. As demand shifts toward more inertial consumers, entry becomes harder, incumbents raise markups, and market share tilts toward larger firms. To quantify this mechanism, I develop and calibrate a firm dynamics model with overlapping generations of consumers who differ in their degree of inertia. Using detailed micro data, I show that younger households are significantly less inertial. The model implies that population aging accounts for 20%–30% of the observed decline in young firms and rise in profits. Reduced-form evidence across U.S. states and product categories supports the model’s predictions.

We present a flexible and scalable computational framework integrating machine learning and optimization theory to solve dynamic adverse selection models with persistent private information and many types. Our approach reformulates the model into a numerically tractable structure that bypasses set-valued dynamic programming; we formally prove that, under verifiable conditions, this relaxation yields the solution to the original problem. The recast problem is solved via a parallelized value function iteration algorithm, where high-dimensional, nonlinear functions are approximated using Gaussian process regression combined with Bayesian active learning. We apply our framework to two previously intractable models: one with persistent hidden information involving up to ten types and another incorporating multiple persistent types and overreporting. Validation against known solutions and rigorous credibility measures confirms accuracy. Allowing overreporting significantly alters long-run contract outcomes, concentrating consumption away from extremes and smoothing utility promises over time.

Market definition is challenging in settings with network effects, where substitution patterns depend on changes in network size. We study these effects in the context of social media. We conduct an incentivized experiment comparing substitution in response to a proposed U.S. TikTok ban, in which all users simultaneously leave the app, with substitution when only a single user deactivates. We find substantially higher valuations of alternative social apps under a collective TikTok ban than under an individual TikTok deactivation. Mechanism evidence shows that both anticipated content-supply shifts and social coordination partly explain the wedge, with the relative importance of each channel varying across platforms. We then show that a collective time limit challenge, where peers jointly reduce TikTok and Instagram use, leads to more time spent on alternative social apps than has been observed in prior individual deactivation experiments. Together, our results suggest that individual-level substitution estimates can be an unreliable guide to market definition for network goods.

We study how firms set wages for their employees when they can legally age-discriminate across workers. We exploit an age-specific minimum wage change in the UK, which raised the minimum applying to workers aged 25 and over, leaving unchanged the minima for younger workers. Using matched employer-employee data on a low-paying sector, we show large, positive wage spillovers on workers aged under 25, which arise within firms from company wage policy. Pay equity norms offer the most parsimonious explanation for the emergence of spillovers. The effects that we document also operate in other low-paying sectors of the UK labor market.

We study how supply disruptions interact with monopoly pricing, inventory management, and consumer stockpiling in a continuous-time model. Preemption incentives—consumers prefer to stock up before a price hike while the firm prefers to hike before consumers stock up—lead to an equilibrium with gradual stockpiling and endogenous uncertainty over the timing of a price hike, which can trigger a run at the disruption onset. Consumer storage introduces welfare losses from randomized pricing, but can also strengthen the firm’s incentive to hold buffer stock. Rationing, price controls, and reserve mandates can each improve welfare, but only strategic government reserves can implement the social optimum.

In this paper, I document systematic heterogeneity in ownership and financing of firms across Eurozone countries. To rationalize these differences, I build a quantitative general equilibrium model of workers and entrepreneurs who choose debt and equity financing of their firms, subject to rich country-specific financial frictions. The novel data on firm ownership and financing, combined with the structure of the model, allows me to quantify the level of debt and equity frictions in each country. Quantitatively, I find much larger output effects from equity frictions: harmonizing them across countries would lead to nearly four times larger output effects compared to debt frictions, and removing them would increase aggregate output by 73% more. The larger impact on output is due not only to the estimated levels and dispersion of equity frictions but also to the greater risk sharing provided by equity, which further incentivizes entrepreneurs to expand their firms. Through their effect on risk sharing, equity frictions also rationalize the observed negative relationship between equity financing and wealth inequality. Quantitatively, they are responsible for over 70% of the explained variation in top wealth shares across countries.

This paper studies how municipal governments jointly manage spending, credit market borrowing, and a public employee pension system. I model governments as levered investors who must meet non-defaultable pension obligations and may value government spending more than citizens. I quantify the model using data on California cities, including a new record of fiscal emergencies, tax increases required to maintain essential city services. After the financial crisis depleted pension funds, cities engaged in excessive risk-taking: the fiscal emergency option encouraged gambling for resurrection that kept cities vulnerable to shocks well into the recovery. To correct this problem, a savings requirement works better than a restriction on risk-taking or a pension funding requirement. The policy experiments emphasize that effective policies need to target the combined pension and bond finances, as policies that only target one, such as a pension funding requirement, are undermined by endogenous changes to the other.

We experimentally study decentralized one-to-one matching markets with transfers. We vary the information available to participants, complete or incomplete, and the surplus structure, supermodular or submodular. Several insights emerge. First, while markets often culminate in efficient matchings, stability is more elusive, reflecting the difficulty of arranging attendant transfers. Second, incomplete information and submodularity present hurdles to efficiency and especially stability; their combination drastically diminishes stability's likelihood. Third, matchings form ``from the top down'' in complete-information supermodular markets, but exhibit many more and less-obviously ordered offers otherwise. Last, participants' market positions matter far more than their dynamic bargaining styles for outcomes.

We show that the emergence of new economic opportunities that draw women away from their traditional domestic roles has significantly influenced the adoption of religious veiling. We measure the prevalence of veiling among young women across Indonesia's districts for more than two decades by hand-coding around a quarter million photographs attached to Indonesia's public high school registers. To establish causality, we exploit exogenous variation generated by international demand for Indonesia's products, interacted with the gender and sectoral composition of local industries. Districts exposed to stronger positive economic shocks---and thus greater economic opportunities for women---exhibit higher rates of veiling adoption. Our findings suggest that veiling facilitates young women's participation in formal labor markets while safeguarding their personal and social image in society.