There's been a big change at the top of the nation's biggest RIA firm, GenSpring Family Offices.

Thomas M. Carroll was named last week as the new CEO of GenSpring, SunTrust bank's wealth management affiliate -- replacing Maria Elena Lagomasino, who had joined the SunTrust unit as CEO in 2005.

An advisory firm formed to serve ultrahigh-net-worth families, GenSpring grew from just $500 million under management in 2001 to nearly $17 billion earlier this year, in part through acquisitions of smaller firms; it ranked No.1 in Financial Planning's 2012 ranking of RIA firms.

But one industry observer says profitability suffered under Lagomasino, a former CEO of JP Morgan Private Bank. "Mel was a great saleswoman, but she wasn't a great businesswoman. So they had great volume and no profitability," the source says. "The historical strategy at wirehouses was to get the brokers to bring the assets in, [and] make money off the assets." But that doesn't work with high-net-worth clients, he says, because they're paying a fee rather than a percentage of AUM.

Neither Lagomasino nor SunTrust responded to immediate requests for comment; the GenSpring offices referred calls to SunTrust.

Carroll is a 16-year SunTrust veteran. Most recently he led SunTrust's Sports and Entertainment Group, which provides private wealth management services to sports, music and entertainment professionals and financial services to sports, music and film organizations.