Finally, after years of tease and denial, the unicorns are going public. These phenomenally valued firms, pumped up by venture capitalists (VCs), remained private for far longer than they did in previous start-up manias, most notably the dot-com bubble of the late 1990s. That’s changing.

A bit of history. In August 1995, Netscape, maker of one of the first web browsers, sold stock to the public for the first time. (Until then, it had been backed and owned by a small circle of managers and VCs.) Initially priced at $14 a share, its handlers, spying fervent demand, doubled the offering price to $28, but by the end of the day it was trading at $58.

Spectators were impressed. Everyone wanted to be the next Netscape, sparking a remarkable five-year period when every lunatic scheme that techies, boosters, and financiers could dream up would sell stock to a lusting public. It was the era of Pets.com, Webvan.com, Kozmo.com — things that look crazy in retrospect but only gloomy Marxists and reactionary permabears thought to be at the time.