The deal makes the two million square-foot building – a 50-story tower overlooking New York’s Central Park and featuring Apple’s flagship Fifth Avenue store – the most expensive US office building.

The news comes amid talks to sell 650 Madison Avenue, another office building close to the General Motors tower, to a group of investors for US$1.29 billion, in yet another pricey transaction. New York-based Crown Acquisitions and real estate investment firm Highgate beat others, including foreign investors, to buy the 27-story office and retail tower from private equity firm Carlyle Group.

In addition to office space, the GM Building and 650 Madison contain extensive space for stores. Rents for retail stores often can be more than triple those for office space, giving both the buildings premium valuation. Still, these deals underscore how the commercial property market is benefiting from foreign investors flocking to US real estate, attracted by stability, higher yields and protection against inflation.

Prices of top Manhattan office buildings have regained much of what they lost in the financial crisis. In April they were roughly 20 per cent below 2007 highs but were trending up, according to the most recent figures from the Green Street Manhattan Office Price Index. Prices of office buildings in the New York Metro area were up 25 per cent year over year in April, with Manhattan up 51 per cent, according to Real Capital Analytics.

“It’s pretty clear to us that New York is one of the safest havens for investment around the world around today,” Haim Chera, principal of Crown, said. “The theory goes that rental growth in hard assets of this quality will be a safe place to protect.”

Chinese investment in US real estate, already on the rise over the past four years, could increase further. Beijing’s State Administration of Foreign Exchange, which manages more than US$3.31 trillion, was reported to be exploring investing in US commercial real estate.

All the interest is good news for the US commercial real estate market. In just the past three days, New York office properties have attracted about US$2.8 billion of investment commitments.

Besides the GM building and 650 Madison Avenue, the source said broker CBRE sold Australian bank Macquarie’s New York headquarters building at 125 West 55th Street in Midtown Manhattan on Friday for more than US$450 million.

The sellers of the 40 per cent stake in the GM building, also called 767 Fifth Avenue, were Goldman Sachs Group’s US Real Estate Opportunities Fund and Meraas Capital on the behalf of Middle Eastern investors. The other 60 per cent is owned by landlord Boston Properties, which together with its partners, paid about US$2.8 billion to acquire the GM building from Macklowe Properties in 2008.

The names of the Middle Eastern investors could not be learned. But the sovereign wealth funds of Qatar and Kuwait invested in the original deal through the Goldman entity, as did a private equity firm affiliated with the ruling family of Dubai.

Zhang planned to invest in the GM building with her own personal wealth, not Soho China’s funds, a source has previously said.

Zhang’s family acquired a 49 per cent stake in Park Avenue Plaza in 2011 for nearly US$600 million. She also tried to provide US$800 million in financing for Vornado Realty Trust to build an office tower above the Port Authority bus terminal in Midtown Manhattan, but that was project was ultimately scrapped.

Darcy Stacom, one of the CBRE brokers on the GM deal, which was first reported by the , could not be reached for comment. Zhang and M. Safra and Co also could not be reached for comment. The deal for the GM stake closed on Friday.

Eastdil Secured handled the sale of 650 Madison Avenue for private equity firm Carlyle Group.

Other bidders included Vornado and a consortium of General Growth Properties and Brookfield Office Properties, Reuters previously reported. The news of the final sale was earlier reported by Bloomberg.