Doing this would cause massive volatility, everybody would be stampeding in and out of assets at the same time. If you really want to stop HFT (which on the evidence available is actually nothing to do will the current market woes) you could simply make order cancellations more expensive, this would stop them all in their tracks. But I think this would solve nothing in the longer term. >IMHO. It was too easy for Greek politicians to take the easy road when Germany's good credit was feeding their addiction. I really don't see the EU coming under one effective fiscal policy, and I think that is the only real solution. For that reason, I think the Euro is probably going to die. Still seems like a political decision to me, the whole reason for the crises lunching from drama to drama is the refusal to let the euro die. But of course politicians would rather do any amount of damage than see their power bases eroded.