“…Third, the mechanism must not run a permanent deficit in funds (budget balance). However, mechanism design theory corroborates that ex post efficiency is not attainable for mechanisms requiring these properties simultaneously (Delacrétaz, Loertscher, Marx, & Wilkening, 2019; Laffont & Maskin, 1979; Myerson & Satterthwaite, 1983). Because ex post efficiency is unattainable, the literature suggests to derive so‐called second‐best mechanisms , which maximize the expected social welfare while maintaining the three desired properties based on appropriate solution concepts (Bierbrauer, Ockenfels, Pollak, & Rückert, 2017; Gresik & Satterthwaite, 1989; Segal & Whinston, 2016).…”