What factors caused a crisis for GM in 2008 that led to its bankruptcy in 2009?

General Motors (GM) was once the largest and most profitable industrial company in the world. But during the last decades, it became one of the least profitable; in 2008, after the economic recession caused a 40% plunge in United States car sales, it was losing so much money that it was forced to ask the government for a loan of billions of dollars to keep it afloat. As an indication of how much the company has shrunk, in 1995, GM employed more than 700,000 people globally; by 2005, this had dropped to 325,000, and by the end of 2009, less than 200,000 as GM continued to lay off or offer buyouts to tens of thousands of its managers and employees.