Quote from slumdog:
yes.. but certain instruments are more easily taxed than others. In the UK shares are taxed regardless of where they are traded and it seems to raise revenue.
The UK stamp duty (tax) raises revenue because it exempts dealers so liquidity is not destroyed. It is only the small trader that gets hit. Just the sort of regressive tax that governments love because it keeps the big boys happy whilst still stealing nickels off the little guys. In Sweden from 84-91 there were no exemptions so there was no reason for the big boys to stay, and so business moved to London.
So you either raise some revenue and screw the little guy or raise no revenue because you don't give exemptions.
Ironic that it's sold as a "bankers tax" that will "raise billions" when the two events are mutually exclusive.