i think you are right, past corrections have been cause dby someone dumping between 100k and 200k btc, i dont think there are many early players left with that amount of BTC that they would dump any time soon.Even if they did this would not move the market as much as it would have in the past, perhaps dropping the price by $10-$15 on a day like today, which would not take long to correct upwards again. It is not likely to start a panic driven sell off instead people will buy in at the lower price cuaing it to gain again.

the big sellers on the silk roads will have that kind of volume to dump if they've been hoarding it.

perhaps but most, if not all, will be selling it almost immediately as they need to re-stock, these people use BTC to facilitate their dealing it is not an investment for them. Plus moving the market takes approx 100,000 BTC, that is about $5m, no vendor is going to be selling drugs if they have that much in BTC.

I wonder if people are worried about the US austerity measures?

--am an economist, and am curious as you to see what will happen

I've looked it up on Wikipedia, but I'm not sure I understand what you mean. These austerity measures would mean that the US increases taxes when people start using Bitcoin, to counter the laundering or something?

No, I was referring to the so-called "sequester" that took place around that comment's day.