.5% tax on each stock, commodity, or derivative trade. It's the same thing.
It would lower your retirement portfolio by 55% of its value (buy = .5%, sell = .5%, 200% turnover/ year; .98^40 = just 45% your retirement portfolio remaining after 40 years). That doesn't even take into account transaction costs (brokerage commissions, bid/ ask spread) going up ~2000% under that tax, which will wipe out a bit more on top of that.
Trading is electronic. So, trading would simply move to Singapore or Hong Kong and other not-transaction taxed markets overnight. Not actually banned in the US; but effectively banned in the US. Companies would simply get off of the New York Stock Exchange and list their companies onto foreign stock exchanges. People would simply stop trading oil and other commodities on the Chicago Mercantile Exchange and start trading them on foreign commodities exchanges.
Investment funds would also move accordingly.
It's not an actual ban. It's just a make-the-US the worst place in the world to do it, make American investment funds the worst place in the world to have your money, and it's all electronic so it can all be moved overseas overnight for 0 cost de facto ban.
Ultimate Irony: The goal is to collect tax revenue on a financial transaction tax. On top of offshoring huge American industries, it will actually lower tax revenue. The loss in capital gains taxes will be larger than any financial transaction tax revenue collected.