Duke Realty Corp. said on Friday that it is selling its suburban office holdings in seven major markets to New York-based Blackstone Group LP, the world’s largest private equity firm, for $1.08 billion.

The sale includes 82 buildings with a combined 10.1 million square feet of space in Atlanta, Chicago, Columbus, Dallas, Minneapolis, Orlando and Tampa.

The sale does not include any properties in Indiana, a company spokeswoman said.

“The portfolio sale is simply a continuation of our strategic plan to reduce our investment in suburban office properties,” Denny Oklak, CEO of Indianapolis-based Duke, said in a prepared statement.

The company said its long-term goal is have 60 percent of its holdings in industrial, 25 percent in office and 15 percent in medical office.

“The transaction generates over $1 billion of capital for the acquisition and development of industrial and medical office assets, and to further de-lever the company's balance sheet,” Oklak said.

Almost 85 percent of the office space Duke is selling is leased and the buildings have an average age of 15 years. Blackstone will take over the leasing and property management responsibility for the buildings.

Blackstone is on a real estate buying spree this year, investing more than $7 billion. The firm is aiming to capitalize on the sharp decline in property values in the wake of the financial crisis.

Shares of Duke rose almost 5 percent on the news Friday, as the broader market also rallied. In late-morning trading, the shares went for $11.20 apiece.