Shit breaks again. It's been covered plenty of times. The fragmentation within the US equities market its beyond management. It gets old repeating the same tune. The SEC is inept, the HFT industry is selfish, and the Academic research on the topic is conflicted and corrupted. The exchanges offer unpublished orders to top bidders and the integrity of the market has vanished.
The garbage was first reported by BATS:
Not even 3 minutes later Nasdaq reports problems:
As is expected, news reading algos go apeshit and flash crash Nasdaq stock:
It's all good though. HFT provide liquidity and tighten spreads...