They dissect the analysis made by the European Commission about the revenues that could be expected from the introduction of a Europe wide FTT and show that there were a number of limitations with the original estimates. The EC's economists reckoned that their tax could result in a total long run loss of GDP of -0.53%. But the new analysis argues that the impact of introducing an FTT could well be at least +0.25%.
I learnt a lot reading the paper, including the fact that the transactions taxes that already exist in 7 countries already raise about $23 billion a year. But, I also learned that the USA has had a transaction tax in place for decades. Here's what they say (page 15):
"The US SEC, the securities regulator, is self-funded by a transaction tax on the volume traded on exchanges. Many who rile against transaction taxes and argue that slight taxes will exact huge disrepair to markets are often unfamiliar that, without the sky falling upon us, the US SEC charges a 0.00257% tax on transactions that today raises a not-trifling $1bn, annually, to fund the SEC. This tax is called “Section 31 fees” after section 31 of the Securities Exchange Act of 1934. These fees were raised in 2010 from 0.0017% - without the sky falling in - and are likely to rise given the additional expenditure at the SEC."They also note that "The US Section 31 fees have been lowered 9 times and raised 7 times since 1934 without stir."' Sounds like just the sort of variable rate FTT that I have been arguing for!