A new trophy-office offering is hitting the market and could sell for in excess of $400 million.

Materials are circulating for the sale of 900 Third Ave., between East 54th and 55th streets, where a large outside glass-covered atrium near the top of the 36-story tower could be transformed into building amenity space.

The Paramount Group ownership has hired the Cushman & Wakefield investment sales team of Adam Spies, Douglas Harmon, Adam Doneger, Kevin Donner, Joshua King and Marcella Fasulo to market the 597,986-square-foot glass-and-steel tower.

Cesar Pelli designed the 1985-era building, which is about 80 percent occupied. The vacancy plus under-market leases provide an opportunity for a “value-add” buyer that likes to work on and upgrade assets.

The brokers did not return requests for comment prior to press time.