When the largest market cap company in the world loses 10% of its market cap thanks to a fat finger from a 100-lot retail-momo-monkey (hitting market order not stop?), questioning your sanity (or the sanity of the hedge fund hotel it has become) is perhaps worthwhile. At 10:57, AAPL was halted as Bloomberg noted: *APPLE HALTED AFTER TRADE AT $542.80/SHR for Reason Code T7 [5] (which seems entirely irrelevant) and then reopened at 11:03 with a small loss. Nothing to see here, move along (except the irony of the fact that the trade occurred on BATS which just IPO'd and the SEC investigation in general on HFT/colos).
Courtesy of NANEX - BATS executed an ugly stub quote...
[6]
[7]
Looking at the ticks initially doesn't look like a flash-crash tumble and more likely a fat-finger indeed.
Chart: Bloomberg