A long time ago, before online broking, I was in a broker's office, (Bridges if I remember correctly). I was buying some St George Bank shares. I looked at his computer at the quotes and asked what is all these things on the screen and he said it is how many shares people want yo buy or sell at what price. I asked him if there are so many people wanting to sell their shares, why should I buy it now? He said those who show their hands on the table are not the real big players. You will see the real players when lines got wiped from the board.
Now that everyone and his dog can see the quotes sitting at home or in the office or even on a bus, I think the large sell orders are there to encourage uninformed people to sell lower than the large order. If there are already 10 million shares offered at say, $1, you are not likely to join the end of the queue trying to sell your 5000 shares. Perhaps the large seller is trying to close his shorts at a lower price.
The other way around when the big boys want to short, they will put in large buy orders to encourage punters to buy their shorts at a higher price.
These days, I take the quotes on the table with a grain of salt. When the real players come in to buy, either the 750K will be pulled or wiped before you can say WTF.
