Completing Markets in a One-Good, Pure Exchange Economy Without State-Contingent Securities

Pareto-efficient consumption in a pure-exchange, one good economy varies over states of nature with respect to only two factors: real aggregate supply and individual utility shocks. One’s optimal contract receipts vary with respect to only these two factors and the ratio of one’s endowment to real aggregate supply. How one’s Pareto-efficient consumption varies with real aggregate supply depends solely on how one’s relative risk aversion compares to the average. Complete markets can be approximately achieved by four contracts dealing with these factors. This has implications concerning central banking, efficient insurance contract design, and a possible new financial innovation.