I was addressing your question of how it would affect you, the small, retail investor. Ultimately, any FTT would increase prices of almost every good and servic

I was addressing your question of how it would affect you, the small, retail investor. Ultimately, any FTT would increase prices of almost every good and service in the economy (oil is traded many times before getting to the pump, debt is perpetually issued to fund capital expenditures, mortgages are resold many times to allocate risk effectively, etc.) You're right in believing that it would disrupt HFT, and that is the intention of the tax. However, my contention is that HFT is, on the whole, beneficial for the financial system, as it improves liquidity and price discovery. Additionally, 0.001% is still larger than you think it is. 0.01% is a unit called a 'basis point'. Many markets (like interest rates and foreign exchange) operate in fractions of a basis point. Also, please reread my previous comment more thoroughly. When I refer to market makers, many (especially in equities) are HFT. You, the retail investor, would immediately see the cost of purchasing stocks increase with a FTT. It would also take longer to execute a trade with fewer market makers (the middlemen you are unknowingly trading with) to provide liquidity on the market.