(Bloomberg) -- A group of Bank of America private bankers that helped anchor the firm's wealth-management practice in one of California's wealthiest enclaves has defected to start an independent company.

The seven advisers, who managed about $3.3 billion in client assets out of Newport Beach, resigned from the bank on Friday, according to Darren Henderson, one of the founders of the new firm. The departures, including five support personnel, make up about a third of Merrill Lynch's private bank staff in the city, he said in an interview.

The group is joining a stream of advisers and private bankers leaving big banks and brokerages to start their own boutiques, hoping to exert more control over their dealings and keep a greater share of the revenue. They are making use of technology ventures that provide record-keeping, custody services and product offerings once available only at the largest firms.

"In the past, we felt like the technology and solutions available to independent firms really didn't measure up," said Henderson, 41.

Joining him at the new firm, Corient Capital Partners LLC, are advisers Chris Copps, 56; Alex Stimpson, 52; Gordon Hassenplug, 49; Jon Tenney, 45; Michael Phelps, 38; and Greg Walters, 33.

The new tech ventures that aid the boutiques are a growing nuisance for banks and brokerages, which have long focused on wresting each others' talent. Firms craft contracts and incentives to lure top producers and prevent their own from defecting. During a conference call with analysts in July, Bank of America Chief Executive Officer Brian Moynihan touted the success of his Merrill Lynch division in that struggle, saying attrition of its top producers is at an "all-time low."

Matt Card, a Bank of America spokesman, reiterated that point when asked to comment on Corient's formation. "Despite the number of advisers in the industry shrinking, Merrill Lynch has recruited more than 150 experienced advisers in 2015," he said. The division has about 14,400 financial advisers and private bankers, and has been a bright spot for Moynihan, boosting revenue and client balances since he took over in 2010.

While it's difficult to find figures that rank the size of teams leaving the largest brokerages to form their own ventures, the Corient group counts as "a very large practice" with an average of about $470 million in client assets managed by each person, said Bill Butterfield, an analyst at Boston-based research firm Aite Group LLC.

Corient already has filed with the Securities and Exchange Commission as a registered investment adviser, or RIA, giving it a legal obligation to put clients' best interests first, whereas brokers are typically required to sell what's suitable. The majority of the firm's business will be fee-based, but employees also will collect some commissions.

The largest independent adviser in Bloomberg Markets' ranking of RIAs was Wetherby Asset Management, with client assets of $3.5 billion as of December 2013. The ranking excludes firms that collect commissions.

As independents, the group will be freer to go after new customers. Bank of America advisers often compete with other employees such as those at its U.S. Trust and advisory units in trying to attract or service the same clients, Henderson said.

"Anytime you are in a big firm, you are constantly bumping into each other," he said. "There's just a lot of sharp elbows."

Henderson and Tenney first worked as analysts at Goldman Sachs Group Inc. with Todd Morgan, Reed Halladay and Darell Krasnoff, who were among the first wave of executives to leave Wall Street and found their own investment advisory firms. In 1997, the trio formed Bel Air Investment Advisors, a Los Angeles-based firm that now manages about $7 billion, according to its website.

The 20,000 independent RIAs in the U.S. have gained market share every year since 2007, more than doubling their assets to $2.7 trillion as of 2014, according to Aite Group. Client assets at the largest retail brokerages of UBS Group AG, Morgan Stanley, Wells Fargo & Co. and Bank of America rose 14% to $6.6 trillion in the same period, Aite said.

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