In what's likely the shape of things to come, Fidelity Investments on Monday said the number of breakaway brokers who chose the company as its custodian doubled during the first half of this year versus all of 2007. And given the recent tumult on Wall Street, Fidelity and rival RIA custodians could see a bonanza if, as expected, more disgruntled broker-dealers bolt the wirehouses to become independent registered investment advisors.

In Fidelity's case, 55 breakaway brokers with more than $7 billion in assets signed up with Fidelity's custodial platform as of the end of June. Among other things, that platform includes support for conversions and practice management, as well as the HybridOne program that handles both commission- and fee-based business at dually registered broker-dealer and RIA firms.

Fidelity had seen an uptick in breakaway broker activity for the past 18 months or so, but the pace accelerated in recent days with the bankruptcy of Lehman Brothers, the sale of Merrill Lynch to Bank of America, and the massive makeover of Wall Street as we knew it. "In the last week alone we spoke to 10 to 12 firms that control $7.5 billion to $8 billion," says Scott Dell'Orfano, executive vice president of Fidelity Institutional Wealth Services, the company's RIA custodian division. "That matched the asset total for the entire first half of the year."

Fidelity custodied roughly $355 billion in assets with more than 3,500 RIA firms as of the end of June. Recent events have caused it to recalculate it's projected growth path. "We believe there will be a significant increase for us," Dell'Orfano says.

And they won't be alone. "The reputation of wirehouses as stalwarts of the financial community has, to put it mildly, been eroded," says Lou Harvey, president of Dalbar, a Boston-based financial services research company. "One of the big reasons brokers stayed with these firms is so they could say to clients 'I'm with so-and-so.' That gave them credibility, and losing that credibility gives them little reason to share their compensation with a big house."