Not exclusively. Coinbase also sells (and buys) bitcoins directly to consumers. In fact, Coinbase is probably the biggest seller of bitcoins in the US (or second biggest after Circle.com - none of these companies publish volume numbers due to competitive reasons).
"Something is going on."
What is going on is very simple: customers of Bitstamp see that bitcoin withdrawals are halted. So the only way to get money out of the exchange is to sell coins and withdraw fiat. This selling activity is what is causing the price to crash. This always happens whenever an exchange halts bitcoin withdrawals (eg. see MtGox's demise in early 2014).
Edit: @TylerE: some customers usually learn about news before others: friends of employees, or even simply the first affected customers (before a public statement is made... remember: rumors spread fast). Again, the same scenario happened with MtGox: the exchange rate started crashing on MtGox a few days before the public news of their insolvency came out. I have been trading BTC for 4 years. I have seen how most of these scenarios play out in the Bitcoin world.
Not exclusively. Coinbase also sells (and buys) bitcoins directly to consumers. In fact, Coinbase is probably the biggest seller of bitcoins in the US (or second biggest after Circle.com - none of these companies publish volume numbers due to competitive reasons).
"Something is going on."
What is going on is very simple: customers of Bitstamp see that bitcoin withdrawals are halted. So the only way to get money out of the exchange is to sell coins and withdraw fiat. This selling activity is what is causing the price to crash. This always happens whenever an exchange halts bitcoin withdrawals (eg. see MtGox's demise in early 2014).
Edit: @TylerE: some customers usually learn about news before others: friends of employees, or even simply the first affected customers (before a public statement is made... remember: rumors spread fast). Again, the same scenario happened with MtGox: the exchange rate started crashing on MtGox a few days before the public news of their insolvency came out. I have been trading BTC for 4 years. I have seen how most of these scenarios play out in the Bitcoin world.