More than five million people became millionaires across the world in 2020 despite economic damage from the Covid-19 pandemic.
While many poor people became poorer, the number of millionaires increased by 5.2 million to 56.1 million globally, Credit Suisse research found.
In 2020, more than 1% of adults worldwide were millionaires for the first time.
Recovering stock markets and soaring house prices helped boost their wealth.
Wealth creation appeared to be "completely detached" from the economic woes of the pandemic, the researchers said.
Lower interest rates and government support programmes had led to "a huge transfer" of wealth from the public sector to the household sector, they added.
This had prompted a surge in household saving, which had "inflated household financial assets and caused household debts to be lower than they would be otherwise".
The number of ultra-high net worth individuals, usually defined as those having investable assets of more than $30m, grew by 24% worldwide in 2020, the fastest rate of increase since 2003.
Credit Suisse said its total of the number of millionaires might be higher than other organisations' estimates because it included both investable and non-investable assets, such as owner-occupied homes.
Anthony Shorrocks, economist and author of the Global Wealth Report, said the pandemic had an "acute short-term impact on global markets", but added this was "largely reversed by the end of June 2020".