The endless towers are the first thing you notice upon arriving in China, and not just because, in most cities, they tend to line the roads leading to the airport. Over the past three decades, China’s cities have welcomed the largest human migration in history. The forest of apartment buildings is the visible manifestation of that movement, and the companies that construct the buildings are no less immense.

Few of those developers loom larger than Evergrande, whose ongoing collapse has riveted China and roiled global markets on Monday, with the S&P 500 falling 1.7 percent.

For many years, Evergrande was China’s second-largest builder and one of the world’s largest companies. Goldman Sachs says its assets are equivalent to 2 percent of China’s GDP; the Financial Times reported the company owned enough land to contain Portugal. CEO Xu Jiayin founded the company in 1996 and used profits from Evergrande’s boom years—China built two United Kingdoms’ worth of housing in the first decade of the century—to invest in all kinds of things, including the Guangzhou soccer team and an electric vehicle company (more on that in a moment).

But the company’s core business of selling apartments relied on borrowing ever, well, grander sums of money under the expectation that revenues would keep up. That hasn’t happened. Evergrande now owes more than $300 billion, and everyone who did business with the company, from steel mills and decorators to would-be homeowners to bond buyers and banks, is being hung out to dry.

The big question is: How far does the fallout extend? Is this China’s Lehman Brothers moment, or are fears of contagion overblown?

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