EnTrust declined disclosing the sale price, citing a confidentiality agreement between the buyer and seller. However, Databank Inc., an Atlanta-based real estate research firm, cites the price at just above $18 million, or $140 per sf.

James I. Clark III, managing principal of Chicago-based EnTrust, says the transaction was unusual in that ESRI made an unsolicited offer for the five-story, 129,421-sf building at Brookside Concourse along Old Milton Parkway, east of Georgia 400. It's also refreshing to have a well-capitalized buyer that also sought to occupy the building, he says.

"This is an all-cash buyer and was not dependent on the financial markets," Clark tells GlobeSt.com. "The field becomes very narrow and these buyers become the choice players to work with."