Quote from traderchi128:
The last thing this tax would do would enhance mkt stability. Volumes would plummet and liquidity would disappear. Spreads would widen out to ridiculous levels causing huge volatility at times. Good luck to the Mutual Fund manager who has to sell hundreds of thousands of shares. Their trades alone would cause stocks that normally aren't that volatile to plummet. Every time these guys went to sell individual stock circuit breakers would be hit.
The people/groups who are so in favor of this tax would take a financial beating as their IRA's and 401k's would get obliterated as the markets plummets.
Last but not least....the tax revenue expected to be generated by this tax would probably be around 10-20% of what they thought. The geniuses that came up with this tax based revenues on what volumes are today. If this tax gets passed volumes will fall by 80% or so.
This tax has no chance of ever being implemented.
This assumes that banks and other big professionals are not exempted. The banks would love this to pass with them getting an exemption. All other market makers would be put out of business which would allow them to control the market and spread. It would widen a bit but not by too much, allowing them to make more money while keeping everyone else out.