Quote from Robert A. Green:
We are looking to show how FTT contributes to:
volatility increasing, not decreasing with FTT 'sands in the wheel';
Spreads increasing between bid and ask, with worse prices for those who use the markets;
More flash crashes with traders not providing liquidity;
Disappointing FTT revenues with transactions moving to non-FTT markets;
Volume reduction shows us the FTT effect, but FTT advocates want sand in the wheels and less volume. They want no HFT volume.
Let's expand and refine the above list of what tell tale signs we can use to prove our point.
The main pro-FTT arguments have to be addressed one at a time:
1) The FTT would raise billions to solve social problems.
The French FTT was projected by the Finance Ministry to generate 1.1 billion euros per year in revenues, or about 90 million euros per month.
http://www.sifma.org/blastemails/global_weekly_update/gfma/gfma-weekly021012.html
Tax revenues can be measured and compared to the official projections.
Losses (jobs/GDP) can also be calculated and their effects subtracted from the FTT revenues.
2) The FTT would tax (punish) banks and financial institutions.
Since MM are exempt from the FTT, who will actually be paying this tax? Pensions? Ordinary man/woman on the street?
This can also be measured.
3) The FTT would decrease market volatility.
Again, this can also be measured.
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When the data is in, each of these elements needs to be addressed.
If the FTT doesn't raise a lot of money, doesn't tax (punish) banks and doesn't decrease volatility, the pro-FTT argument has severely depleted its ammunition.