Aon Center selling for $712 million

A New York-based company struck a deal to buy the 83-story Aon Center, the third-tallest building in Chicago, for $712 million, according to the seller, Piedmont Office Realty Office Trust.

The buyer is a venture of 601W Cos., led by New York real estate investor Mark Karasick. His firm is one of the owners of the two-tower Prudential Plaza next door.

The deal will close in the fourth quarter, according to Piedmont, a Johns Creek, Ga.-based real estate investment trust, which bought the iconic tower for $462.5 million in 2003.

The deal to sell the Aon Center comes a week after news broke that the newly merged Kraft Heinz had signed a 170,000-square-foot headquarters deal in the tower overlooking Millennium Park.