Atlanta-based Jamestown Properties inked a deal to acquire a 40% stake in the 64-story U.S. Steel Tower, Pittsburgh's tallest building. The seller is 601W Cos., which will retain the remaining stake in the building.

The deal values the 2.3M SF building, originally developed in 1970, at about $340M. That is about $90M more than 601W Cos. paid for the structure in 2011, the Pittsburgh Post-Gazette reports, citing Real Estate Alert. 601W Cos. is led by investor Mark Karasick.

The property, which is at 600 Grant St., is 87% occupied. Since owning the building, 601W Cos. has undertaken various renovations costing about $60M, including lobby and elevator improvements.

U.S. Steel still has its HQ in the building. Other tenants include UPMC, Eckert Seamans Cherin & Mellott law firm and accounting firm PwC.

The transaction, when complete, would be Jamestown's first foray into Pittsburgh. It has about $11.2B of assets under management.