This is the new financial term. It means that large unpredictable, unexpected events have big impacts on the markets. I just saw a numb-nut on CNBC stating that two Black Swans are pending, one the unpredictability of LIBOR and the other is inflation. LIBOR has been out of whack since last summer and is the subject of a front page Wall Street Journal article this morning. Commodity prices have been hitting highs for months and food shortages and related riots are well reported. I have read numerous articles that the large cut in interest rates will lead to inflation - plus, this is Econ 101. Neither event, therefore, fit the definition of a Black Swan. When known events and conditions are called Black Swans the term is irrelevant. Here is a good article from the Financial Times discussing Black Swans.