Hey Barneymaroon. To your question "but it does not seem illegal."
Plaese read below.
CORPORATIONS ACT 2001 - SECT 1041C False trading and market rigging--artificially maintaining etc. trading price
(1) A person must not (whether in this jurisdiction or elsewhere) enter into, or engage in, a fictitious or artificial transaction or device if that transaction or device results in:
(a) the price for trading in financial products on a financial market operated in this jurisdiction being maintained, inflated or depressed; or
(b) fluctuations in the price for trading in financial products on a financial market operated in this jurisdiction.
Note 1: Failure to comply with this subsection is an offence (see subsection 1311(1)). For defences to a prosecution based on this subsection, see Division 4.
Note 2: This subsection is also a civil penalty provision (see section 1317E). For relief from liability to a civil penalty relating to this subsection, see Division 4 and section 1317S.