Callan, known for its work with US-based public organizations and pension funds, has four regional offices in addition to its San Francisco headquarters and employs a total of approximately 170 people. Its clients have included the Massachusetts Pensions Reserve Investment Board, Florida State Board of Administration, the Illinois Teachers' Retirement System and Orange County.

Mercer, a subsidiary of Marsh & McLennan Companies Inc., has approximately 1,100 investment consulting employees in 41 offices around the world. Its main investment clients are endowments, corporations, trustees and foundations.

Mercer's global head of investment consulting Andrew Kirton says the merger will create a 400-person US operation with broader capabilities and a larger market share. The merger should go smoothly because the two companies have similar business models, cultures and values, adds Mercer's US investment consulting leader Jeff Schutes.

Callan chief executive Ronald Peyton says that while his company has been a strong player in the investment consulting industry for decades its combination with Mercer will afford its clients "a wider range of tools and resources and enhanced research, educational and quantitative services." An official with Callan did not respond to a request for additional comment.

One of the largest independently-owned investment consulting firms in the nation, Callan keeps its headquarters at 101 California Street in San Francisco, and has four regional offices--Atlanta, Denver, Chicago and Florham Park, NJ. Mercer, which also has offices in each of those markets, says the combined business will continue to have a presence in those cities along with Mercer's other US investment consulting offices in New York, Atlanta, Boston, Dallas, Los Angeles, Philadelphia, Princeton, Richmond, San Francisco, Seattle and Washington, DC. Mercer's San Francisco office is in Four Embarcadero Center.