Could be a number of things. Most likely just a little algorithm which is programmed to buy/sell through out the day.
For example say a big client wants to purchase 10k shares, rather than do them all in one hit and move the price against them, they might be in little clips through out the day. It also takes some of the risk off the broker because if he was to buy them in the morning, then the share price tanked in the afternoon his customer might a little annoyed.
There's other possibilities like its an algorithm searching for stops or trying to scalp each price or something but my guess is its just a buy order being performed through out the day, rather than in one big parcel.