By TheStreet Staff What Caused the Financial Crisis of 2007–2008? How Did it Start?Mortgages sold to U.S. homeowners were responsible for a series of events that caused trillions of dollars in investment losses around the world, nearly collapsing the global financial system and resulting in the Great Recession, the worst economic downturn since the Great Depression. It all began with the U.S. housing market, which in the 1990s and early 2000s was the place to be. Red-hot demand had caused home prices to increase by more than 100 percent in less than 10 years. Housing-related industries made up…