No actually they don't ding bat....but they recognise these trades though.

 

Recent Trades - Last 3 of the day

 

Time ET Ex Price Change Volume Buyer Seller Markers
15:22:17 V 0.04 -0.005 5,000 7 TD Sec 7 TD Sec K
15:14:04 V 0.045   20,000 7 TD Sec 7 TD Sec K
15:14:04 V 0.045   80,000 7 TD Sec 7 TD Sec K