DeBeers controls approximately 30 percent of the world’s supply of
diamonds through its Diamond Trading Company.
Janis Christie/Photodisc/Getty Images
A third, less familiar example has recently gained prominence. In 1970,
three Canadian companies that produce potash in Saskatchewan—a
mineral used to produce fertilizer—created a special company to sell their
product in world markets. Canpotex (named for Canadian potash exports)
now sells about one-third of the world’s potash, and the three companies
restrict their combined annual production in an attempt to influence the
world price. In recent years, Canpotex has also devised special grades of
potash designed to suit specific crops, and in doing so the company has
secured a much larger market share in countries such as South Korea,
Japan, and Taiwan.