possible market manipulation

Apparently there was an order placed to sell 500,000 shares down to 40 cents about an hour before the open this morning. As the time approached 10 am the order was pulled back to 41 cents, then 42 cents then 43 and then pulled completely. This has caused some smaller sellers to drop there sell price below that order to get in the sell que after panicking that there was some bad news coming. It appears that whoever placed and then pulled that sell order may come under ASX investigation for market manipulation.
There was a similar incident last week also.