Can someone explain this course of sales?

[gonk]

Hi,
I've seen these patterns (rapid multiple small parcels) of course of sales appearing for a few stocks and am wondering if anyone can explain the motives and reasons behind them? Thanks in advance.
EG tga today 29Jun
time ssn price num $val
15:05 4103815 1.260 1,000 1,260
15:04 4103594 1.255 12 15
15:04 4103593 1.255 12 15
15:04 4103590 1.255 1,600 2,008
14:55 4099744 1.260 7,935 9,998
14:55 4099743 1.260 11 14
14:55 4099742 1.260 54 68
14:49 4097686 1.260 50,000 63,000 Crossed
14:46 4096367 1.260 9,946 12,532
14:43 4095056 1.260 618 779
14:43 4095055 1.260 12 15
14:43 4095054 1.260 3,952 4,980
14:43 4095053 1.260 872 1,099
14:41 4094411 1.255 12 15
14:39 4093611 1.255 12 15
14:33 4091530 1.255 11 14
14:24 4088332 1.255 10 13
14:22 4087552 1.255 12 15
14:19 4086647 1.255 10 13
14:10 4084071 1.255 9 11
14:04 4081910 1.255 11 14
14:04 4081866 1.255 12 15
14:04 4081865 1.255 12 15
14:04 4081845 1.255 402 505

 

[craigj]

it is bots trading computer algorhyms programs that manipulate trading to keep the share price up or down at a set interval it keeps making a trade