For one thing, as discussed previously[1], Zillow earns commissions and fees when both buying and selling houses, so they may be making money even when the prices nominally show a loss.

For another, even if the majority of the houses were sold at a loss, that statistic by itself tells you nothing about Zillow's overall profit or loss. For example, they might have sold most of the houses for a very small loss, but earned large enough profits on the others to balance those losses out. There simply isn't enough information to say.

[1]: https://news.ycombinator.com/item?id=29060092

1. Invest heavily in real estate, prices keep going up, company gets rich, you get a huge bonus and buy a yacht bigger than Cleveland.

2. Invest heavily in real estate, prices drop, company stock plummets, you're still rich and still have your football-field-sized yacht.

3. Don't invest heavily in real estate, prices keep going up, company misses out, you're still rich and still have your football-field-sized yacht.

4. Don't invest heavily in real estate, prices drop, company doesn't get hurt, you're still rich and still have your football-field-sized yacht.

There's one clearly winning strategy.

But selling for more than they paid isn't the idea. The goal is to capture the ~10% of purchase price that is paid out in fees for a real estate transaction.