Closing price manipulation?

My first post here, but my holding started in 2004, soon after BioMD was floated.
Recently there have often been gaps of 10-20c between the bid and offer prices, and I have noticed several times that, late in the day, a small number of shares were sold down to the Buyer’s bid price, bringing the closing price down below the day’s average price. To illustrate, here are screen shots from the CommSec web site at 4.09pm this Wed. 6th May and Thur. 7th May 2020.

Wednesday -




and Thursday




On Wednesday, most trades were around $7.50, but just before 4pm, 63 were sold down to the Buyer’s bid price of $7.42, and just after 4pm, a Sell order was placed for 5 @ $7.28. At 4.10pm, this was executed for $7.42, which was then the Closing price. The average for the day was $7.497.

On Thursday, most trades were between $7.50 and $7.60, and the last before 4pm was $7.53. A Sell order was then placed for 9, agaiin @ $7.28, and this was executed at 4.10pm for $7.42, so the closing price was down 11c from the last trade before 4pm, and unchanged from Wednesday. The average price on Thursday was $7.532.

Could somebody less naive than me please explain what might be going on here, why would someone be doing that?
Also, on CommSec, I have a minimum limit of $500 per trade - what traders are able to place such low value orders?
Thank you.