Google with Tape Momo:
On April 22, 2013 at 9:37:11.500 (ET), Google Flash Crashed
4. GOOG - Showing trades color coded by exchange.
This is one second of data!
5. GOOG - Showing bids color coded by exchange.There are 5 times as many buy orders as trades. Buy orders were placed and canceled during the 1/2 second drop!