Chicago's Top 10 Office Building Sales of 2015 (So Far)

Summer has yet to sizzle in Chicago and even if the mercury rebounds it wouldn't come close to the red hot market for office buildings in town. Here are the biggest deals of the year to date.

1. Willis Tower $1.3B

The $1.3B sale of Willis Tower was the shot heard around the Windy City. The final price for the city's tallest building was just shy of projections but still enough to set a record sale price for a Chicago office property. The new owner, Blackstone, picked up a hefty $11.4M real estate transfer tax bill in the deal. We're waiting with bated breath for the upcoming renovations the private equity giant has in store for Willis Tower.

2. Mid-Continental Plaza for $367M

The year started with a bang when Prudential agreed to buy the 50-story, 1.3M SF Mid-Continental Plaza at 55 E Monroe St from Walton Street Capital and GlenStar Properties for $367M. The sale price was 55% higher than what Walton and GlenStar paid for the asset in 2005. The companies performed extensive upgrades and boosted occupancy to 86% when it was put up for sale.

3. One South Wacker for $345M

John Hancock Realty added to its downtown portfolio in May with the purchase of this 40-story, 1.1M SF One South Wacker from Harbor Group International for $345M. John Hancock's other holdings include 55 W Monroe, 191 N Wacker, 200 S Wacker and 150 N Michigan. The purchase price on 1 S Wacker breaks down to $288/SF.

4. River Center for $304M

Sterling Bay bought historic 16-story, 830k SF River Center in 2012 for $100M and immediately set to work adding improvements, including a rooftop deck, fitness center and newly renovated lobby. Sterling Bay then locked in tenants such as Gogo, Twitter, Uber, Potbelly and Fieldglass for the 102-year-old, 840k SF building before JP Morgan Asset Management bought the building in April for $304M. Sterling Bay tripled its investment on 111 N Canal with the sale.

5. One North Wacker for $240M

Irvine Co already owned a 49% stake in the 50-story, 1.3M SF One North Wacker before deciding to buy out partner Hines' remaining interest in January for $240M. In a year where nine- and 10-figure deals have been the norm, 1 N Wacker is easily the one that flew under the radar.

6. 300 S Riverside Plaza (land only) for $220M

Joseph Mizrachi and David Werner couldn't get the $335M they sought for 300 S Riverside Plaza, so they decided to sell the building and land separately. The land sold in February for $220M to a JV of World Wide Group and Cammeby's, which then signed Mizrachi and Werner to a 99-year ground lease. Mizrachi and Werner are still seeking a buyer for the 23-story, 1.1M SF structure. Separating the land from the improvements makes valuing the property harder, and if JPMorgan Chase decides to leave after its lease expires in September 2016, the building could operate at a loss because of the ground lease if new tenants aren't found.

7. 550 W Adams for $185M

GLL Real Estate's purchase of the 18-story, 478k SF 550 W Adams in January for $185M is an example of how much of this bull market has been driven by foreign investment. Foreign investors have eyed core assets and markets as safe investments in this market and GLL has been one of the major players. 550 W Adams was 95% occupied at the time of the sale.

8. Corporate 500 Centre for $154M

Corporate 500 Centre at 500 Lake Cook Rd in Deerfield was one of the GE Capital Real Estate holdings that wasn't part of the $23B deal with Blackstone Group and Wells Fargo in April. Cornerstone Real Estate Advisers agreed to buy this four-building, $698k SF campus last month for $154M. The only suburban office sale on this list, the sale of Corporate 550 Centre proved the search for core assets wasn't only relegated to downtown.

9. 515 N State St for $138M

Beacon Capital Partners bought 515 N State St, the 29-story, 623k SF former home to the American Medical Association in January for $138M and sold a 40% stake to Callahan Capital and Ivanoe Cambridge in March. The building is 57% vacant after the AMA left but the owners hope all that available space and planned improvements to the building's lobby and some floors will entice new tenants in short order.

10. One11 West Illinois for $75M

One11 West Illinois, whose $75M sale was announced this week, rounds out the list. GLL bought 111 W Illlinois St, the 10-story, 288k SF home to WeWork and Salesforce.com from Alter Group in the competitive River North office market. GLL gets a quality building that's 99% leased.