Fund manager Invesco Real Estate has completed the purchase for £42m of the 110,000 sq ft office in central Manchester.
The sale represents a net initial yield of 6.3%. The building, designed by Denton Corker Marshall and completed in 2009, is 85% occupied. Tenants include Aecom, Turley Associates and law firm Mills & Reeve.
"We are actively looking at expanding our customer base in Manchester through significant new investment in the science and technology sectors, as well as seeking expansion opportunities in Birmingham and Leeds."
Toby Simon, director of fund management at Invesco Real Estate, said: "The property complements our fund profile well by focusing on strong real estate fundamentals from high quality buildings in core locations."
Bruntwood said the sale will 'enable further growth and diversification' of its portfolio, hinting at further acquisitions with the proceeds. Bruntwood owns 100 buildings in Manchester, Liverpool, Leeds and Birmingham.
Chris Oglesby, chief executive of Bruntwood, said: "Bruntwood has grown through buying problem buildings from other companies and turning them into high quality investments. The difference in pricing between prime investment and those problem buildings has never been wider. This sale is a key part of our growth and diversification plans. We are actively looking at expanding our customer base in Manchester through significant new investment in the science and technology sectors, as well as seeking expansion opportunities in Birmingham and Leeds."
WHR Property Consultants LLP acted on behalf of Invesco; Jones Lang LaSalle advised Bruntwood.
