Feb. 17 (Bloomberg) -- Blackstone Group LP, the private equity firm that bought Equity Office Properties Trust in the biggest leveraged buyout ever, agreed to sell 23 Southern California buildings it acquired in the purchase to Maguire Properties Inc. for about $3 billion, a person familiar with the transaction said.

Maguire, the biggest office landlord in downtown Los Angeles, will gain more than 6.8 million square feet in Orange County and downtown Los Angeles, said the person, who spoke on condition of anonymity.

Blackstone has sold five groups of Equity Office buildings around the country for a total of about $15.6 billion since the Feb. 9 close of its $39 billion takeover of the nation's largest office landlord. Macklowe Properties Inc. bought buildings in New York, Beacon Capital Partners bought buildings in Washington and Seattle, Shorenstein Properties LLC bought in Portland, Oregon, and Irvine Co. bought in the San Diego area.

Maguire will take control of Two California Plaza and 550 South Hope Street in downtown Los Angeles and all of Equity's buildings in Orange County, which would include 21 properties in the cities of Irvine, Santa Ana, Orange, Brea and Anaheim, the person said. Blackstone will retain 15 buildings in Santa Monica, West Los Angeles and Pasadena.

John Ford, a spokesman for Blackstone, and Peggy Moretti, a spokeswoman for Maguire, declined to comment.

Maguire already owns 3.5 million square feet of space in Orange County, including the 1.7 million-square-foot Park Place office campus in Irvine. Chief executive Robert Maguire said in a Feb. 9 earnings call that the company would look for acquisitions that are ``attractive financially and can help us build market share in critical markets.''

Maguire last year entered a joint-venture partnership to own four million square feet of office space in Southern California with Macquarie Office Trust, a unit of Macquarie Bank Ltd., Australia's biggest securities firm. Maguire has a 20 percent ownership stake in the venture and receives fees for managing the property, according to a press release from the companies.

To contact the reporters on this story: Dan Levy in San Francisco at dlevy13@bloomberg.net; Hui-yong Yu in Seattle at hyu@bloomberg.net

Last Updated: February 17, 2007 00:04 EST