Do overconfident and over‐optimistic entrepreneurs invest too much in their companies? Theory and evidence from Italian SMEs

Research Summary: Entrepreneurs often invest a large share of their personal wealth in their firms, exposing themselves to idiosyncratic risk. We propose a theoretical model showing how overconfidence and overoptimism may help to explain this evidence. We focus on overprecision, but we also consider overestimation and overplacement. Numerical examples show a more substantial role for overconfidence than overoptimism in determining entrepreneurs' portfolio allocations. We test the effect of the two latent variables— overconfidence and overoptimism—on small business owners' portfolio allocations. We use a unique dataset including private information on Italian small and medium enterprises and a structural equation modeling approach. A positive relationship between overconfidence and entrepreneurs' investments in their own companies is confirmed. Managerial Summary: We propose a theoretical model showing how overconfidence and overoptimism explain the evidence that entrepreneurs invest a large share of their personal wealth in their firms, exposing themselves to specific risk. Overconfidence leads to underestimating risk, while overoptimism to overestimate expected returns. Using numerical examples, we show a more substantial role for overconfidence than overoptimism in determining entrepreneurs' portfolio allocations. Using a unique dataset including private information on Italian small and medium enterprises, we test our model and find a positive relationship between overconfidence and small business owners' investments in their own companies.