Real Estate

Rosen reconnoitering 350 Madison Avenue

Aby Rosen is itching to get back in the buying game with what could be a $350 million splash.

The German-born — but Americanized — art and landmark-building collector and his co-founder in RFR Realty, Michael Fuchs, are targeting the recently renovated 350 Madison Ave., sources said.

The 394,000 square-foot building is being marketed by Jones Lang LaSalle’s Fearless Foursome — Richard Baxter, Ron Cohen, Scott Latham and Jon Caplan — on behalf of the Nabil and Fouad Chartouni’s Kensico Properties. The brokers did not return calls or e-mails for comment, but the pricing of $888 a square foot would put the deal on the high side of their estimates.

The brothers Chartouni bought it in 2005 for $194.5 million from Monday Properties and the Landis Group.

The Chartounis have since glassed up the old brick façade and lobby with a thoroughly modern vision designed by Moed de Armas & Shannon that also received a 12-year city property-tax renovation exemption.

But the ongoing renovation work kept the office space at just 70 percent occupancy, placing its mortgage on financial-watch lists, while providing potential upside for the next owners. The building’s retail tenant, Paul Stuart, has controlled that space under a long-term lease since 1965.

Rosen and Fuchs already own gems like 17 State St., Lever House and the Seagram Building, and invest in large public artworks. Rosen did not return a call for comment. Stay tuned.

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LivePerson will double its space with a new eight-year, 18,500 square-foot expansion to occupy the third floor of 475 Tenth Ave.

The asking rent was $35 per square foot.

They already occupy 18,500 square feet on the fifth floor in a lease signed in 2010.

The third floor had been rented to Gwathmey Siegel & Associates Architects, which has already moved to 525 Broadway.

Michael Kaufman and Grant Greenspan of the Kaufman Organization represented LivePerson, while Kristin Fisher of the Adler Group represented the building owners in the transaction.