you would impact it only for one day, then the dumping will kill you, you need a constant influx of new money to rise the market price, not a single little pump
also a surging of the price in one sit only, will just lead to a brutal dump, for the weak hands
some bots in mtgox manipulated the price in 2013. I am amazing .... how much bitcoins they had used to manipulate the market ?
some times they use a strategy which involve fake walls, to rise the price, whitout actually selling/buying anything
for example top seller is selling at 250 and top buyer is buying at 240, the top seller and top buyers are bot, the top seller rise his sell to 260, then the top buyers rise it to 250 and so on...
but, what about trading fees ? buying & selling repeatedly will cost nothing ? I think they only paid the fees to manipulate the market ?
trading fee are negligable, they are around 0.25% and with big volume like 5k btc per movements, they fall around 0.1%, so they lose 5 btc, which may look a tons of money for us, but not for someone that has 5k btc...