News announcements frequently coincide with price movements in the market.  Hype in the media about Bitcoins can lead to spike in prices, while negative news can cause the price to drop. In some cases, the negative publicity actually helps to popularize the cryptocurrency, which contributes to its success.
News related to hacking the exchanges or bankruptcy can create bear rumors among users causing the price to plunge. News about the currency being used for selling drugs, laundering money, and other illegal activities can also impact the value of Bitcoins.