We seriously apologize for any inconvenience.

When Bitcoinica was first built, we included a circuit breaker feature to stop trading at one direction when we are out of USD or BTC. However, it has almost never been triggered until today.

Unfortunately, we have a lot of long positions are we're currently unable to fulfill everyone's request to buy. Even though we do not want to interrupt regular market trading activity, we have no case because we don't want to be trading against our customers in this extreme situation.

Liquidation of short positions is also affected but we had no choice. Withdrawal in USD is obviously, also affected. When some more people decided to liquidate their long positions or go short, or more USD funds are deposited, we will adjust the redflag accordingly to allow buying trades.

TL;DR: Bitcoinica can only sell for you at the moment.