We study optimal bidder collusion at first-price auctions when the collusive mechanism only relies on signals about bidders' valuations. We build on Fang and Morris (2006) when two bidders have low or high private valuation of a single object and additionally each receives a private noisy signal...

Cartels were legal to a large extent in Austria until the country’s EU Accession in 1995. We examine archival material on registered horizontal cartels to learn about their inner working. Applying content analysis to legally binding cartel contracts, we comprehensively document different...