Some of the biggest names in commercial real-estate lending have all but turned off the spigot.

With housing in short supply, developers are converting more empty offices into apartments. But not all buildings are candidates for reuse, even as more than one billion square feet of office space sits vacant across the U.S. Photo Illustration: Amber Bragdon Bank regulators are taking a page from their playbook of the 2008-09 financial crisis to help lenders weather the approaching tidal wave of troubled commercial real-estate loans.

A startup firm that is competing with WeWork Cos. in the flexible-office-space business and planning a service that will use blockchain to track space listings just closed a $70 million funding round. Knotel , which was founded in 2016, said the funding round was led by well-known names in the property business, including Newmark Group Inc., a real-estate services firm that went public late last year, and the Moinian Group, a big owner of commercial real estate in the New York region. Other...

The city of South Burlington, Vt., is embarking on a pilot project with a startup blockchain firm in a possible step toward using the technology to replace the city’s system for recording property transactions. Officials with South Burlington and the firm, Propy Inc., said the project would only be a trial run of blockchain, which is best known as the record-keeping technology behind cryptocurrencies like Bitcoin. “When they see that everything works great, they can just take their registry...