Existing evidence shows that risk aversion and trust are largely determined by environmental factors. We test whether one such factor is peer influence. Using random assignment of MBA students to peer groups and predetermined survey responses of economic attitudes, we find causal evidence of positive peer effects in risk aversion and no effects in trust. After the first year of the MBA program, the difference between an individual and her peers' average risk aversion has shrunk by 41%. Finding no peer effects in trust is consistent with recent research showing that distinct cognitive processes govern risk aversion and trust.

We study the influence of multi-sector conglomerate firms on sectoral comovement. Using an innovative network model of firms and industries, we derive a novel measure of the co-concentration of industries in which two industries are more co-concentrated if they share greater exposure to the same conglomerate firms. Using time-series, cross-sectional, and longitudinal tests on establishment-level data from nearly all US firms over 1991 to 2019, we find that industries with higher co-concentration exhibit stronger comovement in employment, sales, and asset growth. Controlling for alternative explanations, a one-standard deviation increase in co-concentration corresponds to a 0.32-standard deviation increase in the comovement of employment growth. In variance-covariance decompositions, we find that firm-specific shocks explain nearly half of aggregate volatility and industry comovement and that conglomerates play a significant role in sectoral comovement. Our framework helps explain how idiosyncratic, firm-level shocks contribute to aggregate fluctuations and influence business cycles.