China has more than 50 million, maybe 60 million, vacant homes, the founder of a Chinese home sharing startup told Fortune’s Most Powerful Women’s conference Tuesday.

Melissa Yang runs Tujia, which has been called the Airbnb of China, but the comparison is misleading for several reasons, not least because Tujia manages 10,000 of its properties.

The estimate of vacant homes in the tens of millions in China might not be shocking to Wall Street bears like James Chanos, who have been calling out China’s housing excess for years. But a credible estimate from a real estate insider like Yang, whose site hosts 400,000 properties, is still jarring. “But this number will only come from me,” Yang said. You won’t find it publicly from any Chinese government figures.

The excess inventory has been a boon to home-sharing businesses like hers, which had the supply, but also had to fight the skeptical tendencies of Chinese users. “There is a huge difference between Chinese travellers and U.S. travelers,” Yang said. “Chinese travellers — they lack trust.”

That’s why Tujia decided to manage 10,000 of its own properties—to build trust with skeptical customers—and what makes it less of a “Chinese Airbnb.”

That, and the amount of vacant housing its users can choose from.