Uber and Lyft have overtones of the wacky days of the dot-com bubble, when sketchy business plans and big losses were an active selling point. The obvious difference between the 1999-2000 boom and the current wave of technology initial public offerings is how badly this year’s high-profile debuts, Uber and Lyft, performed. Uber plummeted on Friday after ringing the NYSE opening bell and fell a bit more this week to leave the stock 11% below the $45 IPO price. Lyft has dived 30% below its IPO price.

Such performance was vanishingly rare during the dot-com boom: In 1999 the average money-losing tech IPO leapt by 81% on its first day, according to data from Prof. Jay Ritter at the University of Florida.

Uber’s weak shares will put a damper on the other stocks waiting to come to market, some of which test investors’ credulity even more than the plans of the money-losing ride-hailing firms.

One reason is that the market is quite different today than in the dot-com boom, at least from the point of view of large companies.

Back in 1999, investors were willing to buy virtually anything and companies and stock promoters obliged, supplying new shares both for staid old-world businesses trying to get online and for hopelessly optimistic startups.