UBS AG, the Swiss lender shrinking its investment banking business, overtook Bank of America Corp. to top a ranking of the world’s biggest wealth managers compiled by Scorpio Partnership.

UBS boosted managed assets by 9.7 percent to $1.7 trillion in 2012 as it benefited from clients invested in emerging markets, the London-based research company said in a study of more than 200 firms published today. That outstripped a 5.9 percent gain to $1.67 trillion at Bank of America.

Global wealth management assets rose 8.7 percent to $18.5 trillion last year, helped by a 24 percent increase in net new money and market gains, according to Scorpio. The Standard and Poor’s 500 Index advanced 13 percent in 2012 year while the MSCI Emerging Markets Index climbed 15 percent.

“The sharp uptick is a turnaround for the private banking industry, which has struggled to attract convincing levels of new client assets since the financial crisis,” Scorpio said in an e-mailed statement. “Private banks have bounced back from their nadir of 2011.”

Wells Fargo & Co., another of the eight U.S.-based private banks on the list, was third, followed by Morgan Stanley.

The top 20 firms are outpacing rest of the industry as two- fifths of clients express a preference for a single wealth manager, compared with 14 percent who opt to use more than one bank, according to Scorpio. The top 20 managers grew assets almost 11 percent and oversee 76 percent of the total funds held by private banks, Scorpio said.

Earnings Growth

Still, the pace of earnings growth at wealth managers slowed last year amid rising operating costs, according to Scorpio. Profit climbed by an average of 9.8 percent in 2012, compared with 12.3 percent in 2011.

Spain’s Banco Santander SA returned to the top 20 ranking for the first time since 2010 after reporting a 66 percent increase in assets under management from buying out minority shareholders in Banco Espanol de Credito SA, a consumer bank which includes the Banif private banking arm.

Julius Baer Group Ltd. may climb the ranking this year after the Zurich-based bank agreed to buy Bank of America’s wealth management business outside the U.S. That could boost managed assets by as much as 72 billion Swiss francs ($74 billion), Julius Baer has said.