I don't think you can dominate the market with only 1k coins. the total volume of okcoin is 56,682.36฿ alone.(in last 24h).
What exchange are you looking at, bitstamp?
Bitstamp doesn't lead, bitstamp follows okcoin.(because of the 'low' volume)
So if there was any manipulation it would happen on okcoin.
Besides these blocks are probably just an accumulation of coins from a lot of people.
Yes, BitStamp, and also have access and currently looking at BitFinex, Kraken, Houbi, Btc-E, and BtcChina on my screens, I quite disagree about OkCoin driving it, as there are a lot of BTCs in BitSTamp's wallet to even drive BitFinex now!
I just noticed now that DownBlock have just been pushed downwards another $5.
I initially thought it's a group of people, but when I started seeing the blocks moving programatically, the only explanation is that it's an organised movement, it's by someone knowing exactly what they're doing.
BTC could be going down again (slower).