June 17 (Bloomberg) -- Societe Generale SA, France's second- largest bank by market value, bought a 37 percent stake in Rockefeller Financial Services Inc. for an undisclosed price to add wealthy clients in the U.S.

SG Private Banking and Rockefeller & Co., the wealth- management unit of Rockefeller Financial Services, will work together to offer services to clients with at least $30 million to invest, said James McDonald, chief executive officer of Rockefeller & Co., at a press conference in Paris today.

The deal is the second in North America this year for Paris- based Societe Generale's private-banking arm, following the February acquisition of CWM Group Inc., a Calgary-based wealth manager with C$650 million ($637 million) of assets. The U.S. has almost 40,000 ultra high net worth individuals, those with more than $30 million, according to a report last year by Cap Gemini SA and Merrill Lynch & Co.

``This is something of a coup for SocGen to secure the deal because if it had been known that Rockefeller was looking for an alliance there would have been a long queue,'' said Sebastian Dovey, director of consulting firm Scorpio Partnership Ltd. in London. ``Rockefeller is almost an entirely U.S. book of business.''

Societe Generale rose 1.86 euros, or 3.2 percent, to 60 euros in Paris trading. The shares have declined 35 percent this year, valuing the bank at 35 billion euros ($54.3 billion).

John D. Rockefeller

Rockefeller & Co., a closely held money manager, traces its origins to the 1880s, when John D. Rockefeller Sr. relocated his oil business to New York from Cleveland and hired people to manage his personal affairs. Rockefeller & Co. was formally organized in 1979 and began taking in money from family friends in the early 1990s, before expanding to include a larger range of rich clients.

Societe Generale's private-banking arm had 71.7 billion euros under management on March 31, while New York-based Rockefeller oversees almost $30 billion. The French bank doesn't have an option to increase the stake, said Daniel Truchi, head of Societe Generale's private bank.

``Rockefeller had the intention to develop not only in the U.S., but worldwide, and we wanted to develop in the U.S.,'' Truchi said in an interview with Bloomberg Television. ``Overall, this makes quite a significant alliance.''

Rockefeller's clients can benefit from Societe Generale's knowledge of structured products, hedge funds and fund research, Truchi said. Rockefeller and the French company's private banking unit can develop global offers for very rich families, he said.

`Right Steps'

The deal comes less than five months after Societe Generale announced a 4.9 billion-euro loss resulting from unauthorized trading. The Paris-based bank was forced to raise 5.5 billion euros in a share sale to replenish capital after the loss and writedowns linked to the collapse of the U.S. subprime market.

While the record trading loss did unsettle some of the private bank's clients, it didn't imperil the talks with Rockefeller, which began about a year ago, Truchi said.

``We did a lot of diligence about this problem,'' Rockefeller's McDonald said in an interview. ``We believe that SG has taken all the right steps to assure that this won't happen again and of course they have recapitalized the bank through a very successful rights offering.''

Clients of Societe Generale's private bank added a net 400 million euros in the first quarter, down from 2 billion euros a year earlier, the company said on May 13. The second quarter ``looks very good with a strong trend in assets, especially in April,'' Truchi said today.

SG Private Banking set a target in February to double gross operating income by 2010 from 224 million euros in 2006. The private-banking unit also aims to manage 115 billion euros of assets in the same period.

The unit, created in 1997, employs more than 2,700 people in 25 countries, and typically targets clients with more than 1 million euros.

To contact the reporter on this story: Fabio Benedetti-Valentini in Paris at fbenedettiva@bloomberg.net; Fabienne Lissak in Paris at flissak@bloomberg.net.

Last Updated: June 17, 2008 12:51 EDT