It's more likely to be a large holder waiting for sufficient liquidity to be available for them to cash out.
These alt coin markets are tiny. Look at the order book. It's all decimals of BTC that are on there. There's no liquidity to speak of - unlike, say BTC-e Bitcoin and Litecoin markets. That's why exchanges like BTCe don't bother with other alts. the volume in the mainstream coins is huge - pros that trade 50-100 BTC at a time.
If you have even 1 large holder who has a lot of BC wanting to profit take, you'd see exactly the pattern you've observed: wait for liquidity to emerge, cash out a load, then wait another 10 hours or so for the bid side to "recharge" itself, cash out again, rinse and repeat.
I don't think there needs to be any conspiracy associated with it - and even if there was, they'd still need to have the BC to be able to place the order s there's no material difference to what I've just described.
There are 75 million BC's in circulation. That is quite a large amount. It means that BC is already at a tenth of Peercoin's price corrected for coin supply. So even if it got to Peercoin's valuation it would only be a tenfold gain from here whereas the buy in required would be many hundreds of times the buy in that was needed to get this far.
Taking all this into account, it's not a bad point for a large holder to "get off the bus" since they could take the view that there's more chance of it going down than up from here. THat's what's behind those big sellwalls.
Think of a funnel with the hole plugged. It takes only 10 cc to get a 5 cm rise in water level but a 100cc to get the next 5cm rise. That's where BC is right now.
+1
I agree, thats exactly my analysis.