DAVOS, Switzerland—The chill in the air here last week wasn’t just from the altitude.

A sharp slide in public and private valuations for prominent technology firms hung like a snow cloud over the World Economic Forum’s annual event this year. As investors and entrepreneurs crammed into meetings and parties in this mountain town, many wondered if the tech boom was finally cooling off.

“Obviously there are a lot of unicorns,” said Nathan Blecharczyk, co-founder and chief technology officer of Airbnb Inc., referring to venture capital-backed startups with a valuation of more than $1 billion. “Some of those unicorns won’t survive.”

For years, the tech sector was going nowhere but up. Fast-spreading connectivity promised a massive potential market for large Internet firms. Artificial intelligence and new data-analytics tools would help companies and governments gain orders of magnitude in efficiency.

Davos organizers themed this year’s meeting around harnessing the massive transformation that technology can offer, dubbing it the fourth industrial revolution.