FORTUNE — When Facebook FB first tried to trade as a public company in May 2012, it didn’t work. Literally. The NASDAQ machinery was overwhelmed, causing so much chaos that the exchange eventually paid out $10 million in the largest SEC penalty of its kind.

At the time, some speculated if the Facebook experience would cause future new issuers to choose The New York Stock Exchange. But it didn’t come to pass. In fact, NASDAQ actually made up ground.

Between January 2011 and April 2012, there were 92 NASDAQ IPOs and 119 NYSE IPOs. Between June 2012 and the present, there have been 100 NASDAQ IPOs and 110 NYSE IPOs. In other words, NASDAQ actually has been gaining market share when it comes to number of issuers.

Seems that companies accepted two arguments being put forth by NASDAQ’s NDAQ  new listings department: (1) The Facebook situation was an anomaly caused by record-breaking volume that would not be applicable to most other listings; and (2) Even if such volume is repeated, we fixed the glitch.

All of which brings us to today, when NASDAQ’s entire system went dark for more than three hours. No trading of Facebook or Apple GOOG or Amazon AMZN . No trading of options. No nothing.

How on earth are NASDAQ’s listings folks supposed to spin this? Every single company on the exchange has been affected, not just the super-popular ones. And this is the second major technical problem in two years. Even if this one is fixed — and it is beginning to be as of this writing — what assurances can be made that another isn’t just around the corner. Does anyone want to risk becoming the next Regado Biosciences  RGDO , which priced a small IPO last night and found itself stuck in limbo during its first day of trading?

NASDAQ pulled a rabbit out of its hat once, but this time it will be much more difficult…

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