“It truly is an unknown,” Barry Diller, Expedia’s chairman, said of the coronavirus on an investor call last month. “All we’re trying to do is separate what we absolutely believe is the effect of the virus from our ongoing business, so we can prepare ourselves and make that ongoing business as strong as possible when this thing is over.”

One of the hardest hit may be Airbnb, where millions of hosts have listed their properties for short stays since the company was founded in 2008. (Airbnb takes a cut of their fee.) Over the years, Airbnb hosts have become increasingly sophisticated, with mini-economies springing up to cater to the hosts’ needs for cleaning and management of the properties. Competitors like Booking.com followed by moving into rentals of vacation homes.

Now Airbnb finds itself on strategically tricky ground.

The San Francisco company, valued at $31 billion by private investors, said in September that it planned to go public this year — even though the initial public offering market for high-profile, money-losing start-ups has been rocky. Airbnb has indicated that it planned to go public via an unusual method known as a direct listing, where no new shares are sold. And it is under pressure to complete a listing this year because some of its current and former employees’ shares in the company will otherwise expire.

The offering may now be in question. Nick Papas, an Airbnb spokesman, would only refer to the company’s previous announcement that it planned to go public this year. But stock market volatility and a big blow to business from the virus may make it unthinkable for any company to go public soon.

Last week, Brian Chesky, Airbnb’s chief executive, sent an email to employees outlining the company’s response to the virus. In the message, he said Airbnb would grant some refunds to customers and establish a $10 million fund to support Chinese rental operators while tourism to the country, where the outbreak started, has halted.