Former Nasdaq CEO Bob Greifeld warns that this year's IPO boom feels similar to the late 1990s tech bubble.
"In a sense, it reminded me back of the dot-com era, when you had companies going public that had no known path to profitability," he says. "We shouldn't be sounding great alarm bells" about IPOs, Greifeld says, but he adds that "post-WeWork, if you don't have a path to profitability, you're going to need that."