In a surprise move the Swiss National Bank removed its rate cap on the Swiss Franc.  The effect on markets around the world was largely negative, demonstrating the influence that the central bank of even a relatively small country can have around the world.  Two good articles on the matter:

http://www.bloomberg.com/news/2015-01-15/snb-officials-eating-words-risk-long-lasting-market-indigestion.html

http://www.marketwatch.com/story/us-stocks-rebound-on-tap-as-futures-surge-with-big-bank-earnings-ahead-2015-01-15?dist=lcountdown