Sherman Anti-Trust Act

Market allocations are situations where competitors agree to not compete with each other in specific markets, by dividing up geographic areas, types of products, or types of customers. Market allocations are another form of price fixing. All horizontal market allocations are illegal per se. If there are only two computer manufacturers in the country and they enter into a market allocation agreement whereby manufacturer A will only sell to retailers east of the Mississippi and manufacturer B will only sell to retailers west of the Mississippi, they have created monopolies for themselves, a violation of the Sherman Act. Likewise, it is an illegal agreement that manufacturer A will only sell to retailers C and D and manufacturer B will only sell to retailers E and F.

Territorial and customer vertical market allocations are not per se illegal but are judged by the Rule of Reason. In 1985, the Justice Department announced that it would not challenge any restraints by a company that has less than 10 percent of the relevant market or whose vertical price index, a measure of the relevant market share, indicates that collusion and exclusion are not possible for that company in that market.