UBS saw its assets under management grow by about $30bn (£19bn, €23bn) in 2013, the biggest gain of any wealth management operation, boosted by a growing legion of millionaires in China and India, according to a report by Private Banker International.
The Swiss bank saw its assets grow by 14% to $245bn, increasing from 2012's figure of £215bn. Citigroup was the next biggest gainer, up to $238bn from $210bn a year earlier.
Asian banks boosted their share of regional wealth assets to a record 13.2% from 11.5% in 2012, Bloomberg reported from a wealth conference in Singapore.
The number of Asia-Pacific millionaires grew by 17% last year, according to Cap Gemini SA and Royal Bank of Canada.
Credit Suisse was third, HSBC fourth and Deutsche Bank in Asia replaced JP Morgan in fifth place.
JPMorgan slipped to seventh place behind Switzerland's Julius Baer Group, according to Private Banker's Asia wealth-management rankings.
UBS is understood to have hired 88 additional wealth advisers this year to deal with Asia's high-net-worth (HNW) market. They are based mainly in Hong Kong and bring the bank's tally of advisers in Asia to 1,120.
Total assets under management in Asia increased 18% in 2013 to a record $1.4tn, according to Private Banker.