The National Resident Matching program strives for a stable matching of medical students to teaching hospitals. With the presence of couples, stable matchings need not exist. For any student preferences, we show that each instance of a stable matching problem has a 'nearby' instance with a table...

This paper introduces a model of endogenous network formation and systemic risk. In it, agents form networks that efficiently trade-off the possibility of systemic risk with the benefits of trade. Second, fundamentally ‘safer' economies generate higher interconnectedness, which in turn leads...

Risk compensation can undermine the ability of partially-effective vaccines to curb infectious-disease epidemics: Vaccinated agents may optimally choose to engage in more risky interactions and, as a result, may increase everyone's infection probability. We show that — in contrast to the...

This paper introduces a simple model of endogenous network formation and systemic risk. In the model, firms form joint ventures called ‘links' which are subsequently subjected to shocks that are either good or bad. Bad shocks incentivize default. Links yield full benefits only if the...

The fear of contracting a serious illness caused by a contagious disease limits economic activity even after reopening. Widespread testing alone will not alleviate this problem. We argue that targeted testing in concert with targeted transfers is essential. We propose a model with these features...

The problem of allocating bundles of indivisible objects without transfers arises in the assignment of courses to students, of computing resources like CPU time, memory and disk space to computing tasks and the truck loads of food to food banks. In these settings the complementarities in...

We study a model of network externalities transmitted over links wherein the externalities stem from links themselves rather than nodes. For example, bilateral investments can fail and trigger cascading defaults of firms. Joint research projects can succeed and innovations can be diffused over...