[pdovy]

It's better to miss an opportunity than potentially expose yourself to a loss. If the exchange side system has become obviously unreliable (not responding to requests would count here), it's generally wise to stop trading.

I can see the temptation to just forge ahead on a one time only event like an IPO, but if you do so then I think you need to be prepared for the consequences. I also imagine that part of the usage terms for direct access include something that limit Nasdaq's liability in the event of a system error, so I'm not sure how UBS thinks they will get around that.