Sterling Bay's purchases of Prudential Plaza and 600 West Chicago propelled Chicago's 2018 office building trade volume past last year's totals already, and with six months remaining and several trophy assets on the market, deal volume may wind up at its highest since the record peak of 2015.

Combined sales volume in Q1 and Q2 accounted for $3.3B, CommercialCafé reports. By comparison, only $3.1B in commercial buildings sold for the entirety of 2017.

Business picked up considerably in Q2, with Sterling Bay's $680M acquisition of Prudential Plaza leading the way. It was the most expensive deal since Blackstone Group's $1.3B purchase of Willis Tower in 2015. The second quarter accounted for $1.84B in deal volume, the largest quarterly total in five years and a jaw-dropping 772% year-over-year increase.

The other major deals sealed in Q2 include Brookfield Properties' $305M purchase of 175 West Jackson, billionaire Joe Mansueto's $255M investment in the Wrigley Building, Harrison Street Real Estate Capital's $240M acquisition of an eight-building medical office portfolio from DuPage Medical Group and Angelo Gordon's $148M purchase of Presidents Plaza.