Of course, our markets are subject to many regulations. I don't see how it follows that we need more regulations, specifically banning or taxing HFT. HFT is already taxed, btw. Everyone pay SEC fees in the US on stock sales and stamp tax in the UK. Traders pay income taxes on their trading income. Common sense says, unless there is some clearly demonstrated harm to society from HFT, leave it alone ( subject to existing regulations)