Some of techs biggest unicorns, including Uber and Lyft, appear to be accelerating their plans to go public. Others such as Airbnb and Slack have stated they are "readying" to IPO but have not set formal timelines.
Mr. Miller said that he expected a robust year for I.P.O.s next year, but that companies may not want to wait until too late in the year to file. “There are certainly some storm clouds on the horizon,” he said. Some unicorns are sidestepping the unpredictability altogether. WeWork, an office rental company valued at $45 billion, has been widely named as an I.P.O. candidate. But in November, the company agreed to sell an additional $3 billion of shares to its main investor, SoftBank’s Vision fund. That deal has allowed WeWork to push plans for a public listing further into the future, said a person familiar with the company.