High commissions in the U.S. residential real estate agency market pose a puzzle for economic theory because brokerage is not a concentrated industry. We model brokered markets as a game in which agents post prices for customers and then choose which other agents to work with. We show that there exists an equilibrium in which each agent conditions working with other agents on those agents' posted prices. Prices can therefore be meaningfully higher than the competitive level (for a fixed discount factor), regardless of the number of agents. Thus, brokered markets can remain uncompetitive even with low concentration and easy entry.

Current refugee resettlement processes account for neither the preferences of refugees nor the priorities of hosting communities. We introduce a new framework for matching with multidimensional knapsack constraints that captures the (possibly multidimensional) sizes of refugee families and the capacities of communities. We propose four refugee resettlement mechanisms and two solution concepts that can be used in refugee resettlement matching under various institutional and informational constraints. Our theoretical results and simulations using refugee resettlement data suggest that preference-based matching mechanisms can improve match efficiency, respect priorities of communities, and incentivize refugees to report where they would prefer to settle.

Many markets are syndicated, including those for initial public offerings, club deal leveraged buyouts, and debt issuances; in such markets, each winning bidder invites competitors to join a syndicate to complete production. We show that in syndicated markets, collusion may become easier as market concentration falls and market entry may facilitate collusion. In particular, firms can sustain collusion by refusing to syndicate with any firm that undercuts the collusive price, thereby raising that firm’s production costs. Our results can thus rationalize the paradoxical empirical observations that many real-world syndicated markets exhibit seemingly collusive pricing despite low levels of market concentration.

We propose an economic framework for determining the optimal allocation of a scarce supply of vaccines that become gradually available during a public health crisis, such as the COVID-19 pandemic. Agents differ in observable and unobservable characteristics, and the designer maximizes a social welfare function over all feasible mechanisms—accounting for agents’ characteristics, as well as their endogenous behavior in the face of the pandemic. The framework emphasizes the role of externalities and incorporates equity as well as efficiency concerns. Our results provide an economic justification for providing vaccines immediately and for free to some groups of agents, while at the same time showing that a carefully constructed pricing mechanism can improve outcomes by screening for individuals with the highest private and social benefits of receiving the vaccine. The solution casts light on the classic question of whether prices or priorities should be used to allocate scarce public resources under externalities and equity concerns.

We study the link between market forces, cross-sectional inequality, and intergenerational mobility. Emphasizing complementarities in the production of human capital, we show that wealthy parents invest, on average, more in their offspring than poorer ones. As a result, economic status persists across generations even in a world with perfect capital markets and without differences in innate ability. In fact, under certain conditions, successive generations of the same family may cease to regress toward the mean. We also consider how short- and long-run mobility are affected by changes in the returns to human capital.

We show that in the presence of admissions reserves, the effect of the precedence order (i.e., the order in which different types of seats are filled) is comparable to the effect of adjusting reserve sizes. Either lowering the precedence of reserve seats at a school or increasing the school’s reserve size weakly increases reserve-group assignment at that school. Using data from Boston Public Schools, we show that reserve and precedence adjustments have similar quantitative effects. Transparency about these issues—in particular, how precedence unintentionally undermined intended policy—led to the elimination of walk zone reserves in Boston’s public school match.

We introduce a model in which agents in a network can trade via bilateral contracts. We find that when continuous transfers are allowed and utilities are quasi-linear, the full substitutability of preferences is sufficient to guarantee the existence of stable outcomes for any underlying network structure. Furthermore, the set of stable outcomes is essentially equivalent to the set of competitive equilibria, and all stable outcomes are in the core and are efficient. By contrast, for any domain of preferences strictly larger than that of full substitutability, the existence of stable outcomes and competitive equilibria cannot be guaranteed.