Thanks for that explanation KSE. I remember reading somewhere...

Thanks for that explanation KSE. I remember reading somewhere how commissions are provided in some exchanges for improving liquidity

I am assuming you work for a broker????

There is no statutory limitation on the size of orders. The $500 order is imposed by brokers, not the regulators.

http://www.asx.com.au/products/algorithmic_trading.htm

In this case the closing of the share price at 2c even when the bulk of trades had gone through at 2.1c is intended to dissuade people from bidding up the share price and reducing the price of their bids. You can see the 2c bid line has shrunk (in part yes, because of selling into the line) and the 2.1c ask line has increased.