Making good on its promise to bulk up in asset management, City National Bank (CYN) in Los Angeles announced Wednesday that it is buying Rochdale Investment Management in New York and combining it with its asset management subsidiary.

Rochdale is a $4.8 billion-asset firm that manages assets for high-net-worth clients and their financial planners throughout the country.

Its merger into City National would create an $18 billion-asset firm offering a wide array of traditional and alternative investments to wealthy clients. The unit would operate as City National Rochdale Investment Management within City National's wealth management group. A deal price was not disclosed.

"This is not just an acquisition, but rather a constructive combination of two complementary companies that share the same values," said City National Chairman and Chief Executive Officer Russell Goldsmith in a news release. "The result is a much stronger and diversified national wealth management company with the scale and skills to do even more for its clients and colleagues and our shareholders.

Goldsmith told investors and analysts in a conference call last week that City National was eyeing acquisitions of both banks and asset firms. The $24 billion-asset bank is also expanding in specialty lending; on Monday it announced plans to buy First American Equipment Finance, a leasing firm in Rochester, N.Y. City National said that Rochdale's CEO, Garrett D'Alessandro, would head the combined asset management firm and would report to Richard Gershen, the executive vice president of City National's wealth management group.

The deal is expected to close later this quarter. City National said it would be mostly accretive to earnings in 2012.

-- This article first appeared on American Banker.