Besides Bitfinex's problems other reason for this decrease is that $19 million in bitcoin were sold in australia.
Anyway you don't have to worry,ups and downs are normal and as someone mentioned before this is a good chance to take advantage and buy some btc.
People shouldn't worry about the bitcoins being sold by the Australia government. The price will never be known and just like previous US auctions, they are not likely to affect the market price.