The richest 1% now has as much wealth as the rest of the world combined, according to Oxfam.
It uses data from Credit Suisse from October for the report, which urges leaders meeting in Davos this week to take action on inequality.
Oxfam also calculated that the richest 62 people in the world had as much wealth as the poorest half of the global population.
It criticised the work of lobbyists and the amount of money kept in tax havens.
Oxfam predicted that the 1% would overtake the rest of the world this time last year.
It takes cash and assets worth $68,800 (£48,300) to get into the top 10%, and $760,000 (£533,000) to be in the 1%. That means that if you own an average house in London without a mortgage, you are probably in the 1%.
The figures carry various caveats, for example, information about the wealth of the super-rich is hard to come by, which Credit Suisse says means its estimates of the proportion of wealth held by the 10% and the 1% is “likely to err on the low side”.
As a global report, the figures also necessarily include some estimates of levels of wealth in countries from which accurate statistics are not available.
Some free market think tanks questioned the credibility of the figures.
The Institute of Economic Affairs’ director general Mark Littlewood said the statistics were “bogus”.
“The methodology of adding up assets and subtracting debts and then making a global ‘net wealth’ distribution implies that many of the poorest in the world are those in advanced countries with high debts. Whilst we might have sympathy for the Harvard law graduate’s plight, it is unclear that worrying about her should be the focus of a development organisation,” he said.
The Adam Smith Institute’s head of research Ben Southwood also said the data was “misleading”.
“More meaningful measures show greater equality. Those in the middle and bottom of the world income distribution have all got pay rises of around 40% between 1988-2008. Global inequality of life expectancy and height are narrowing too—showing better nutrition and better healthcare where it matters most.