The effect of experts' opinion on prices of art works: The case of Peter Brueghel the Younger

Experts’ opinion affects prices of traded goods in several markets. In the art markets, their role is especially important but hard to identify. We focus on the unique case of leading expert Klaus Ertz, who published a catalogue raisonné in 2000 to clarify attributions of paintings by Old Master Pieter Brueghel the Younger, who was abundantly copied. We collected the sales of his paintings (autograph) as well as those from his atelier and followers (non-autograph) over the period 1972–2017. Using a difference-in-difference identification strategy, we establish that Ertz’s expertise had a significant effect on the prices of autograph works: Buyers were willing to pay roughly 60% more for works sold at auctions considered autograph after Ertz’s intervention.