Having IPO'd at $45 (raising around $74 billion), Uber's is the biggest IPO since Alibaba.

But this morning, faced with an ugly market background, Uber's indicative range has collapsed from around $48 to finally open at $42...popped, then traded back below the open...

Not an auspicious start (but of course, the asset-gatherers and commission-rakers will remind everyone that Facebook fell after its IPO before soaring).

"How did the bankers get this so wrong" exclaimed one CNBC anchor...

Cramer warned:  "They have to get it to 46 if UBER does not want to be the end of the unicorn era"