Expectations matter for economic activity. To the extent that they are fundamentally unwarranted, they represent "undue optimism or pessimism" (Pigou, 1927). In this paper, we identify empirically the effect of undue optimism/pessism ("optimism shocks") on economic activity. In a first step, we...

We assess the contribution of "undue optimism" (Pigou) to short-run fluctuations. In our analysis, optimism pertains to total factor productivity which determines economic activity in the long run, but is not contemporaneously observed by market participants. In order to recover optimism shocks...