Ready to trade? On budget-balanced efficient trade with uncertain arrival

This paper studies the design of efficient mechanisms for repeated bilateral trade in settings where (i) traders' values and costs evolve randomly with time, and (ii) the traders become ready and available to participate in the mechanism at random times. Under a weak condition, analogous to the non-overlapping supports condition of Myerson and Satterthwaite (1983), efficient trade is only feasible if the mechanism runs an expected budget deficit. The smallest such deficit is attainable by a sequence of static mechanisms.