Gig economy companies also have not proved a business fundamental: that they can make money. While Lyft and Uber have been expanding rapidly, they have lost close to or more than $1 billion a year. And the companies are spending heavily on new initiatives like food delivery, electric bikes and self-driving vehicles, making profits a distant prospect.

[Unicorns are riding into the public markets, and their elite early investors will be the biggest winners.]

Even so, Lyft’s offering means that people will now own shares of the company in their mutual funds and stock portfolios, giving them more of a vested interest in the financial outcomes of gig economy firms. That will be compounded when Uber, the world’s biggest ride-hailing operator, goes public in the next few months in what is expected to be the largest initial public offering of the past five years. Uber will almost certainly become part of index funds, which underlie the retirement portfolios of millions of Americans.

“Their business model is completely reliant on an unsettled issue, which is the status of their drivers,” Veena Dubal, an employment and labor law professor at the University of California’s Hastings College of the Law, said of ride-hailing companies. “They’ve been trying to shift risk onto workers, and now they are shifting risk onto investors as well.”

Those risks sent jitters through some investors on Friday, with Lyft’s shares falling after opening up strongly. The stock dipped to roughly $80 before declining further near the end of trading to finish the day at $78.29.