The Achnacarry Agreement oil cartel predated OPEC
This oil cartel predated the OPEC cartel, and was made up of Anglo-Persian Oil Company (which became BP), Shell, Gulf Oil and Standard Oil.
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“A new book traces the story of the secretive “Achnacarry Agreement” that was forged in the [Scottish ] Highlands in 1928 and led to major players in the oil industry establishing a cartel designed to steady a volatile market and protect the interests of the oil company.”
… “Over the next five years the price of East Texas crude would be ruthlessly cut from 98 cents a barrel to just 10 cents a barrel, forcing many wildcatters and smaller oil companies out of business. Those that clung on were forced to sign up to strict production quotas that have remained in place until today.”