I did it once with one of the alt coins with about $1000 in its early stage.
I bought up about $200 worth, which was a lot for such a small market.
Then I put half of that for sale (let's say 10 coinz per $1) of 1000 coins at $1.05.
With such a 'big' sale, other sellers put their bids at $1.04, $1.03, $1.02...etc...they kept their bids lower than mine because they knew the market would not go above my sell for a long time.
When someone puts their bid at $.98 I put another sell of 1000 at $1.00 solidifying that $.98 and more smaller sell orders at $.97...$.96...$.95.
Push it down as far as you can before you start seeing walls building on the other side. Then you start buying up coins in small quantities...keeping the price low with all new sellers. Move the big wall of 1000 coins from $1.05 down to $.97 ensuring that the price is going down and now is the time to sell.
Once I have the other $800 turned into coinz at $.95...I drop the wall at $.97. The price starts going up...the spring has sprung...the price continues rising, pull the sell at $1.05, other walls fall...the price is now over $1.10. Start selling a few at a time during the rally until you end up with $1,100. A 10% profit with a little bit of manipulation.
Now imagine this on a larger scale with $1 million.
Plus they use one exchange (see: BitStamp) to move the price while their main money sits on another exchange gobbling up the change in market moves.
Traders who figure out the production cost on the coin will not buy into this fake wall bs. It can be done on new coin because the market depth is shallow and not large enough to attract sharks.
Bitcoin is an ocean with not just a few dozen sharks constantly watching. You think these sharks here do not know the cheapest way to acquire/produce the coins and buy up any coin with deep discount?