We offer a propensity score perspective to interpret and analyze the marginal treatment effect (MTE). Specifically, we redefine MTE as the expected treatment effect conditional on the propensity score and a latent variable representing unobserved resistance to treatment. As with the original MTE, the redefined MTE can be used as a building block for constructing standard causal estimands. The weights associated with the new MTE, however, are simpler, more intuitive, and easier to compute. Moreover, the redefined MTE immediately reveals treatment effect heterogeneity among individuals at the margin of treatment, enabling us to evaluate a wide range of policy effects.

This paper studies economies where firms acquire capital in primary markets and then, after idiosyncratic productivity shocks, retrade it in secondary markets that incorporate bilateral trade with search, bargaining, and liquidity frictions. We distinguish between full or partial sales (one firm gets all or some of the other’s capital) and document several long- and short-run empirical patterns between these variables and the cost of liquidity, as measured by inflation. Quantitatively, the model can match these patterns plus the standard business cycle facts. We also investigate the impact of search frictions, monetary and fiscal policy, persistence in shocks, and returns to scale.