$50-60 billion is the amount of illicit money that disappears from the continent of Africa as a result of tax avoidance by multinationals/foreign companies operating in Africa. This economic sabotage is carried out through a process called TRANSFER PRICING (OR MISPRICING).

Source: Thabo Mbeki-led High-Level Panel on Illicit Financial Flows

Transfer pricing happens whenever two companies that are part of the same multinational group trade with each other: when a US-based subsidiary of Coca-Cola, for example, buys something from a French-based subsidiary of Coca-Cola. When the parties establish a price for the transaction, this is transfer pricing.

Transfer pricing is not, in itself, illegal or necessarily abusive. What is illegal or abusive is transfer mispricing, also known as transfer pricing manipulation or abusive transfer pricing. (Transfer mispricing is a form of a more general phenomenon known as trade mispricing, which includes trade between unrelated or apparently unrelated parties.)