Piedmont Office Realty Trust has sold the Aon Center in Chicago for $712m (€649m), 12 years after buying it for $462m.

The city’s third-largest office tower has been acquired by private New York-based 601W Companies, a week after Kraft Heinz Company revealed it would be relocating its headquarters to the 83-storey, 2.7m sqft building.

The 601W Companies, which is led by New York investor Mark Karasick, already owns the two-tower Prudential Plaza next to Aon Center.

The purchase marks a bet that companies will lease space in Chicago’s East Loop area, which encompasses offices, hotels and condo towers adjacent to a more recently-constructed park and cultural complex.

The area’s 16.5% office vacancy rate was the highest of all downtown submarkets during the second quarter, according to CBRE.

A signal that the wager is well-timed came last week when the newly merged Kraft Heinz Company said it has taken 170,000 sqft of space across five floors of the Aon Center, to relocate its headquarters from a Chicago suburb to downtown.

The sale was “the culmination of Piedmont’s long-term strategy of transforming the asset into one of Chicago’s most prestigious office towers,” said Piedmont president and CEO Donald Miller in a statement.

The Aon Center is 86% leased, Piedmont said. In addition to Kraft Heinz, Piedmont has signed new tenants including KPMG, Microsoft, United Health Group, Integrys, and the Federal Home Loan Bank of Chicago since buying the property, while retaining tenants including Aon, JLL, AT&T and Edelman.

The transaction is expected to close early in the fourth quarter. Piedmont declined to disclose the cap rate for the transaction or the amount of capital invested in the Aon Center since purchasing the tower in 2003.

Piedmont anticipates receiving net sales proceeds of approximately $640m. The Georgia-based real estate investment trust (REIT) said it intends to use the proceeds to enhance its balance sheet through debt reduction and to position the Company to fund other opportunities that could include acquisitions and share repurchases.

Constructed at the height of Chicago’s skyscraper boom in 1972, Aon Center was originally the Amoco Building, named for the major integrated oil company that is now part of BP.

Also built at that time were the John Hancock Building in the North Michigan Avenue shopping district and the Willis Tower in the central office area. Blackstone bought Willis Tower earlier this year for $1.3bn in a transaction that is expected to include major renovations.

Aon Center sits at the north end of Millennium Park, a major tourist destination that includes a theatre, an outdoor performing arts pavilion and a skywalk connecting to the Renzo Piano-designed modern wing of the Art Institute of Chicago.