Passage of the Sherman Act in the United States in 1890 set the stage for a century of jurisprudence regarding monopoly, cartels, and oligopoly. Among American statutes that regulate commerce, the Sherman Act is unequaled in its generality. The Act outlawed "every contract, combination or...

A supplier is known to be subject to opportunism when contracting secretly with downstream competitors, particularly when downstream firms have "passive beliefs." We stress that in many situations, an equilibrium with passive beliefs may not exist and passive beliefs appear less plausible than...