Quote from ZeroSigma: current market volume would not change (remaining 'static') - a very optimistic assumption, [/B]
After receiving plenty of feedback from the trading community (thank you all), and having finally located the primary source of the $150bn figure (Dean Baker's 2000 self-published article entitled "Taxing Financial Speculation - Shifting the Tax Burden from Wages to Wagers") I was able to make some interesting changes to the article.
While it has to be admitted that Mr. Baker did not assume 'static' tax income (assuming instead a 1/3 volume declines across asset classes, which at least for stocks would be consistent with the Chinese rate increase from 0.2% to 0.5%), a more serious mistake has instead emerged: as much as 2/3 of the $150 billion figure widely quoted in the media is obviously missing from the current bill proposed by Rep. DeFazio, simply due to the exemption for government bonds, corporate bonds and currencies, all of which were assumed by Mr. Baker to be taxed at a 0.1% rate, and all of which have been omitted from the current legislative proposal (see section 4475 of the HR 4191 Act, which should have enumerated them explicitly - correct me if I'm wrong!)
So the article concludes now as follows:
These three asset classes missing from the DeFazio proposal are: Government Bonds, Corporate Bonds, and Currencies, which by Mr. Baker's own estimate should have been responsible for almost 2/3 of the overall $120 billion tax revenue, i.e. around $95 billion ($27.7bn, $14.7bn, and $33.3bn, in total $75.7 billion in 2000, so using Mr. Baker's 1.25 adjustment factor, in "current money" the missing revenue would amount to $94.6 billion).
Even Mr. Baker's estimate made for stocks ($36.5 billion) looks like taken from an entirely different tax, because it is based on a higher tax rate of 0.5%, not 0.25%. This two-fold increase in the tax rate for equities can be possibly justified by an optimistic assumption that both sides of every transaction can be always taxed, without any customer-firm transactions in which only one side is taxed, and the other (market-making firm) is exempt. The missing 95 billion dollars annually cannot be so readily justified though.