question on current low volume buying

Afternoon all :) I've been keeping my eye on the depth of MTU for a while now, and often see occurances like the below happening:

01:01:25 PM 1.620 4
12:56:25 PM 1.620 4
12:48:25 PM 1.620 4
12:42:25 PM 1.620 4
12:33:10 PM 1.620 4
12:26:39 PM 1.620 4
12:23:09 PM 1.620 4
12:18:24 PM 1.620 4
12:16:08 PM 1.620 4
11:59:05 AM 1.620 4

So this appears to be people (or the same person/broker/whatever) buying tiny parcels at fairly regular intervals throughout the day. Historically it tends to end with a large purchase towards close that either pushes the SP up or down a fair bit.

Just wondering what the logic is here :)

Thanks all