Behavioral Finance in Joseph de la Vega's Confusion de Confusiones

In this paper, we link Joseph de la Vega's work Confusion de Confusiones, written in 1688, with current behavioral finance and propose that Vega be considered the first precursor of modern behavioral finance. In addition to describing excessive trading, overreaction and underreaction, and the disposition effect, Vega vividly portrays how investors behaved 300 years ago and includes interesting documentation on investor biases, such as herding, overconfidence, and regret aversion.