The proportion of adults in families owning multiple properties has seen a 30% surge during the 21st Century alone, according to a think-tank.
Around 10.3% of adults were in families with multiple property wealth in 2012-14, compared with 7.9% in 2000-02, marking a 30% increase, analysis by the Resolution Foundation found.
Some 5.2 million people now have second homes, it said.
Combined with falls in home ownership generally, the rise of second home-owning in 21st Century Britain is behind an increasing concentration of property wealth, according to the Foundation, whose work aims to improve living standards for people on low to middle incomes.
In contrast to the one in 10 adults with multiple sources of property wealth, four in 10 (40%) adults have no property wealth at all, up from 35% in 2000-02, it said.
The analysis found that alongside an increase in the number of people with additional property, the average value of assets held in these properties has grown by 20% in real terms between 2000-02 and 2012-14.
There is a generational split, with baby boomers aged 52 to 71 the most likely to be multiple home owners, accounting for more than half (52%) of all the wealth held in additional properties.
Generation X, made up of 37 to 51-year-olds, accounts for a further quarter (25%) of additional property wealth.
But millennials born since 1981 own just 3% of the additional property assets, the research found.
In 2016, a stamp duty hike was imposed on people buying second homes in England, Wales and Northern Ireland, with changes also made in Scotland, where stamp duty has been abolished, to mirror the rest of the UK.
Laura Gardiner, a senior policy analyst at the Resolution Foundation, said second home owners tend to be baby boomers living in the South and East of England, who are very wealthy compared with their peers.
She said: "Multiple property ownership is still a minority sport, but a growing one that represents a significant boost to the wealth pots of those lucky enough to own second homes.
"People with second homes not only have an investment that they can turn to in times of need, for instance in later life when care is required, but if the property is rented out they also see a boost to their incomes here and now."
The findings were made using a range of figures, including Office for National Statistics (ONS) data.