A report from aid agency Oxfam says the 85 richest people own the equivalent wealth of half the world's population.
The report, Working for the Few, has been published as the World Economic Forum in Davos says income inequality is a top priority.
Executive director of Oxfam Winnie Biyaniyima called for action from those attending the forum.
"We have arguments that are appealing both the to the stinking rich and to those who are attracted to moral argument. For those who are thinking about economies and growth, then need to know that this kind of inequality does not encourage growth, it stalls growth. It causes insecurity, it causes social instability, and all this undermines the profit-seeker's motive."
Research by the charity suggests that the imbalance is having a detrimental effect on the world, as individuals and companies hide trillions of dollars away in a web of tax havens.