(Dow Jones) The big Wall Street brokerages may have little to fear from the much-reported move to independence by a growing number of financial advisors, according to new research from Cerulli Associates.

The so-called wirehouses will employ fewer brokers in coming years, but those brokers will be more productive as they hone in on wealthier clients, the research firm says in a report to be released this week. While some big-revenue brokers have grabbed headlines for going independent, it's moderate producers who are more likely to join or create an independent firm, Cerulli says.

There has been a slow migration of brokers to independent channels, and registered investment advisors gained 0.9% market share of advisor-managed assets between 2007 and 2008. But wirehouses still control almost $4 trillion in clients assets-nearly half the assets managed by U.S. financial advisors, the report finds.

Wirehouse brokers' market share of client assets will slide to 41% by year-end 2012, Cerulli projects. But it will still be two and a half times the size of runner-up independent broker-dealers, whose share is projected to reach 16% during the same period.

The approximately 310,000 practicing financial advisors in the U.S. managed about $8.3 trillion in assets at the end of 2008, a 26% decrease from $11.2 trillion the previous year, Cerulli estimates. The drop was due primarily to capital market losses.

Wall Street brokerages have been encouraging their employees to team up in recent years to divide responsibilities and develop deeper areas of expertise. Firms also hoped clients who had relationships with multiple advisors would be less likely to move if one of their advisors changed firms.

While this trend has led to whole teams moving, these are more likely to be midsize teams managing between $75 million and $200 million in assets, according to Cerulli.

"This was surprising," says Bing Waldert, a Cerulli director and lead author of the report. "We expected to see larger teams leaving."

A slightly larger percentage of big teams than mid-sized ones moved to an independent model between 2004 and 2008, but a smaller percentage of big teams have expressed a desire to go independent in the future. Large wirehouse brokers who make a move are most likely to join a competitor, Cerulli says.

That's partly because larger teams provide a broader range of services for clients, which ties them more closely to big financial institutions, Waldert says. For example, a team serving corporate executives might look to its firm's trading desk for help managing clients' restricted stock, while the investment banking division might help small business owners determine the value of their companies.