cartel

A group of independent producers or sellers who collude to fix prices, limit supply, or divide markets — acting collectively as a monopoly to increase profits at consumers' expense. Illegal in most jurisdictions.

• cartelization/ˌkɑːrtəlaɪˈzeɪʃən/(n)卡特尔化

• drug cartel
• oil cartel
• price-fixing cartel
• cartel agreement
• break up a cartel
• OPEC cartel

1. 1.OPEC is essentially a legal cartel — oil-producing nations coordinate production quotas to influence global oil prices, something that would be illegal for private companies. (commodity cartel)
2. 2.The EU fined five major banks €1 billion for forming a forex cartel that rigged currency exchange rates through a private chat room called "The Cartel." (price-fixing conspiracy)

• trust/trʌst/— a group of companies acting as one — historical term
• syndicate/ˈsɪndɪkət/— a group combining for a common purpose
• price-fixing ring (a group coordinating prices)

from German "Kartell" (agreement between hostile parties) — from Italian "cartello" (placard, poster) — from Latin "carta" (paper) — originally a written agreement, now a secret one