WThis doctoral thesis focuses on the effects of investor sentiment on asset pricing and the challenges of portfolio optimization under parameter uncertainty. The first essay "Sentiment risk premia in the cross-section of global equity" applies a recently developed sentiment proxy to the...

Models recently studied by Farmer (2012, 2013, 2015) predict that, due to labor-market frictions and "animal spirits", stock-market fluctuations should Granger cause fluctuations of the unemployment rate. We performed several Granger-causality tests on more than half a century of data of German...