Advisors that manage $500 million or more in client assets comprise just 11 percent of practices, but they service nearly two-thirds of the industry's assets, according to a new report.

Such "mega teams" are continuing to expand their market share and their influence in the advisory industry, with growth between 2012 and 2017 that has exceeded that of smaller firms, according to a study released Wednesday by Cerulli Associates.

"Though the wirehouses and hybrid registered investment advisors have the greatest concentration of these teams, their influence is steadily growing throughout the industry," the report's authors stated.

The U.S. wealth management industry comprises over 300,000 advisors who manage $20.3 trillion in client assets, the report said. The four biggest wirehouse firms -- Morgan Stanley, Merrill Lynch, UBS and Wells Fargo -- control 35.4 percent of the industry’s assets, compared with 37 percent for independent broker-dealers, RIAs and hybrid RIAs combined, the report said.

In the wirehouse sector alone, mega teams grew their assets under management by 19 percent over the five-year period studied, Cerulli said.

Advisors appear to be embracing the benefits that consolidation brings, both in terms of economies of scale and impact on client services, the report said.

“Teaming allows advisors to build specialized roles and responsibilities, thereby delivering broader and deeper advice to clients with more complex financial needs,” Marina Shtyrkov, a research analyst at Cerulli, said in a prepared statement.

A Cerulli survey found that 73 of advisors believed that teaming improves the client experience.

The growth of mega teams could turn out to be a boon to asset managers, the report added.

"For asset managers, mega teams represent attractive distribution opportunities," the report said. "They commonly retain investment decisions and use diverse products and services."