Interesting thought: Would the CEOs of the exchanges know the reason for the low price? I mean, they obviously know who are dumping and putting up huge ask walls. If the account belongs to payment processing companies, obviously they are cashing out highly likely due to the coins from merchants. If the account belongs to institutional funds, obviously they are trying to control the price. If the account belongs to miners, obviously they are cashing out mined coins.
As many people have noted, in spite of all the talk about adoption there is still comparatively little demand for use as e-currency (and what is bought for that use is usually sold back on the exchanges very soon, since most merchants prefer to get the cash). Therefore the price is still sustained entirely by demand from speculators and investors.
I would further claim that the price is sustained entirely by
short-term speculation, and mostly in the Chinese exchanges. I believe that the price generally fell from ~800$ to ~400$ from February to April because their interest in bitcoin was wearing out fast. The cause of that may have been the perceived hostile attitude of the PBoC, the MtGOX debacle, or ordinary clients losing money to a few high-frequency or leveraged traders.
By my reading, after the final tough stance by the government in late April or early May, the exchanges made the field more level and reassured their clients through their joint announcement. That got the price stabilized at 450$.
In my view the late May mini-bubble was due to a surge in demand in Chine, too. I still don't knwo what caused that demand, but anyway it seems to have all but collapsed, so the price is almost back to the pre-bubble level.
But even the 450--475$ price is still held up by the Chinese short-term speculators. If it weren't for them, the price would be less than 350$, perhaps as low as 150$.
If there is manipulation by a few "whales", it is to keep the price up rather than down. I see hints of that since late May and even now. However I don't see how that could be profitable; it seems that it would take a lot of money to just fight a natural downwards trend. Perhaps those whales were just speculating, only with some insider knowledge that made them more optimistic than the average client.