The study found that 147 companies formed a 'super entity' within this, controlling 40 per cent of its wealth. All own part or all of one another. Most are banks - the top 20 includes Barclays and Goldman Sachs. But the close connections mean that the network could be vulnerable to collapse.
'In effect, less than one per cent of the companies were able to control 40 per cent of the entire network,' says James Glattfelder, a complex systems theorist at the Swiss Federal Institute in Zurich, who co-wrote the research, to be published in the journal PLoS One.
Some of the assumptions underlying the study have come in for criticism - such as the idea that ownership equates to control. But the Swiss researchers have no axe to grind: they simply applied mathematical models usually used to model natural systems to the world economy, using data from Orbis 2007, a database listing 37 million companies and investors.