Wells Fargo & Co opened its new Abbot Downing business today, officially merging two of its wealth management units under a new brand that it hopes will expand its market share of America’s richest families, Reuters said.

The new business, catering to individuals and families with $50 million or more in investable assets, is named after the 19th-century New Hampshire builder of the stagecoaches that have come to represent Wells Fargo.

Since Wells Fargo first publicly announced the planned merger in November, the combined business has grown roughly 20 percent to $32.9 billion in client assets under management.

In those five months, the group added five billionaires and 13 individuals with $100 million or more in investable assets to its client base, said Abbot Downing President Jim Steiner.

Steiner said the biggest drivers of new wealth have been cash from the sale of company stakes through initial public offerings and mergers and acquisitions.

Steiner estimated that about 10,000 households in the United States have $5 million or more in investable assets. In an October study of 72 multifamily advising firms, the average client asset size was $48.4 million, according to research and consulting firm Family Wealth Alliance, Reuters said.