I've been spending a bit too long keeping an eye on the trading patterns recently, and I reckon there's some serious market manipulation going on, with relatively tiny amounts of trades (for currency traders) resulting in near instantaneous significant swings in the price.
For example on 18th Nov 1750 bitcoin trades trigger a 40% rise, 19th Nov, 1500 bitcoin trades worth £750k triggered a near immediate 25% reduction in value, then nearly as many again resulting in a 20% rise, prior to a further 30% fall until on the 20th 1250 bitcoins, total value of just £375k of trades kickstarted the rally that ended up with prices going back up 70%... and then 1200 trades pretty much ended that rise.
By my reckoning that's probably the same trader or traders who've just manipulated the market to cash out £750k, use half of that to then buy nearly the same number of bitcoins again a day later at around a 40% reduction in price, then flog them again when they'd risen 60%.
There also seem to be a lot of shorter term patterns of people triggering reductions and rises of a few percent within the space of a few minutes with similarly sized trades.
Basically the market size seems to be so small that it takes less than a million quid to trigger huge swings in the market, and more than double their money inside a week.
Thing is, people have to have also been buying all the bitcoins they flog at the top of the market, so the person manipulating the market has effectively knowingly ripped them off, knowing full well that they're intending to flog enough rapidly to trigger a rapid fall in the price so they can then buy the same number back again at a huge discount shortly after... probably a fair few of them from the same people who're panic selling after seeing themselves lose 25-40% in the space of a few hours.
So if you've got a million or so to manipulate the market with, then there's probably no quicker way to double your money... if not, then I guess you can try to ride on their coat tails, but beware that you could well be buying from the traders who've just caused the big rise and is cashing out to deliberately cause the market to crash.