I wonder if today is "the day"? Down nearly 25% in the last 24 hours, and down 12% in the last 3... Some major trades too, over US$500,000 value each. Some of the futures traders are going to get slaughtered, especially if they're leveraged to any significant extent. If there are enough "sob stories" in the papers, I guess it's theoretically possible the various futures/options will be withdrawn from sale (new ones, I mean - I can't imagine the existing ones would somehow be clawed back).