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Re:Trading Halted in Nasdaq-Listed Securities Due to Technic... by resu on Thursday August 22, 2013 @10:31PM (#6261368)
Yes, I think very many are dependent on these feeds. As you mentioned, they are the official prices and are referenced for compliance with all those damn regulations and most of the market relies on them so it'd be pretty much impossible to facilitate trading while it's down.

Also, trading in any derivative that is based on any underlying in the feed will be very problematic because that's where the underlying spot price come from. Options trading for example were entirely shut down in those symbols while the feed was down.

Re:Trading Halted in Nasdaq-Listed Securities Due to Technic... by insaneirish on Thursday August 22, 2013 @11:52PM (#6261613)
All the consolidated feeds, CTS, CQS, UTDF, UQDF are consumed for options, but they are a secondary thing and not used for pricing in real time.

Raw feeds are used. That said, Nasdaq is the most important underlier for many things in options, and that could be why some options trading stopped.

Re:Trading Halted in Nasdaq-Listed Securities Due to Technic... by resu on Friday August 23, 2013 @09:27AM (#6263379)
PHLX, NOM, ISE/Gemini all halted trading and all exchanges halted options trading on Nasdaq listed symbols until Nasdaq came back up at ~3:40. Yes, most sophisticated co-located firms probably use raw feeds, but how do you facilitate trading when the official feed for the underlying is down and the symbols aren't even trading on their listed exchange? (Nasdaq down from ~12 to ~3:40)