AAPL Stub Quote
A stub quote $27 below best bid executed in Bats-Y.
One second interval chart of AAPL showing BATS trades (pink) and NBBO (National Best Bid/Offer) shaded gray for normal market, yellow for locked market (bid = ask) or red for crossed market (bid > ask).
Nanex also reported:
Here are other examples I saw in real-time with HFTAlert Pro:
SLV 1 Minute Chart
SLV HFT Alert Pro Raw Quote Bursts
USO 1 Minute Chart
Yahoo ran real hard for an extended period as more Red Bloomberg Headlines ran regarding them seeking liquidity and offering up part of its business to Alibaba. You'll notice on the first table that YHOO was quoting and trading across 6 different exchanges. When the largest candle appeared on the price chart, YHOO traded Nasdaq (NQEX) only.
YHOO 1 Minute Chart
YHOO HFT Alert Pro Raw Quote Bursts staring at 14:26:41 and running until 14:28:20