The real reason why retail investors weren't impacted by the NYSE's halt is a hard truth... to retail investors, the NYSE is always dark
Where Do Retail Investor Orders Go? The simple answer: to the highest contracted bidder. Stock "wholesalers" or internalizers like Citadel or Knight pay retail brokers lots of cash to execute retail trades, essentially creating a "third market". Why? Because in a high frequency trading world, where stock prices have never been more fuzzy to the end user, but crystal clear to those that spend enormous sums on colocation and PhD employees, it's never been easier to print money (not unlike Bernie Madoff's scheme in the 90's). But that is the subject of a much, much longer story. Someone should write a book.