Cushman & Wakefield and HFF have been appointed to sell for 45 Cannon Street, EC4, for £145.8m.
AOG Real Estate and partner Morgan Capital completed the 85,362 sq ft office in late 2017.
It is now almost entirely let, with the final floor under offer and the majority of space taken by Global Relay and OpenText. There is also 7,000 sq ft of ground-floor retail.