How Macklowe’s boom might go bust

The fate of New York City’s most valuable office building — and the man who owns it — has real estate insiders on the edge of their seats. The General Motors Building is just one of the many gleaming skyscrapers real estate mogul Harry Macklowe put up as collateral when he borrowed billions to finance his purchase of seven Class A properties from the Blackstone Group last February. Now, with the credit markets roiling from the subprime fallout, with as much as $3.5 billion in short-term debt coming due in just four months, and a portfolio of some of New York City’s top office assets at risk, the storyline of the 70-year-old titan is the best the industry has seen in years.