This story gives the impression that you can somehow magically make a profit by buying a house, waiting a few months, and selling it. This is completely ignoring the concept that most of the data is going to be from house flippers who don't just buy and sell houses, but renovate houses. If you are a professional who buys fixer-uppers that no one else wants the hassle of dealing with, then put a lot of money and work and skill into them, yes you have a good chance of selling it for more than you spent on it.<p>If you just buy and sell, and don't do anything to the house, you're very likely to lose money (when factoring in transaction costs) unless you really know what is happening in the market. People see what you bought the house for a few months ago, why would they pay more than you did? Also, as many others have mentioned, there is a lot of selection bias. People are less likely to sell if they have to sell for a loss, if they have to hold onto a property they <i>wanted</i> to sell because they would lose money if they sold, they don't show up in this data.