Wu believes Opendoor can buy and sell homes, in quantity, by employing the type of data analysis that has powered so many Silicon Valley companies and by targeting the broad middle of the market. It deals in single-family homes built after 1960, priced between $125,000 and $500,000. It has no interest in distressed properties, which require too much work, or in luxury properties, which are harder to value. ... Of course, buying up houses to make a market is capital-intensive, and the risks are great. Opendoor has raised $110 million in equity from Khosla Ventures, GGV Capital and Access Industries, among others, most recently at a valuation of $580 million earlier this year. And it has also raised more than $400 million in debt to buy the homes. To succeed, it has to price the homes it buys accurately, without seeing them, and it has to sell them quickly to minimize the costs of carrying them. ... Opendoor is a big, bold play in a market with $1.4 trillion in annual transaction volume that’s been largely undisturbed for decades. ... the model has yet to be tested by a recession or a market crash, which can catch even the smartest players by surprise. Wu says he modeled the business through the 2008 subprime crisis to understand the risk.