We estimate risk aversion from the actual financial decisions of 2,168 investors in Lending Club (LC), a person-to-person lending platform. We develop a methodology that allows us to estimate risk aversion parameters from each portfolio choice. Since the same individual makes repeated investments, we are able to construct a panel of risk aversion parameters that we use to disentangle heterogeneity in attitudes towards risk from the elasticity of investor-specific risk aversion to changes in wealth. In the cross section, we find that wealthier investors are more risk averse. Using changes in house prices as a source of variation, we find that investors become more risk averse after a negative wealth shock. These preferences consistently extr...