Sweden tried to tax before. Read what happened:
http://www.ft.com/intl/cms/s/0/b9b40fee-9236-11e2-851f-00144feabdc0.html#axzz3ZlWZhZYV
Initially, the tax rate was 0.5 per cent in connection with the purchase and sale of shares. In mid-1986, the rate was doubled and the tax base was broadened to cover share options and convertibles. The trading volume on the Stockholm stock exchange changed dramatically when the tax was increased. Average turnover fell 30 per cent during the second half of 1986 and throughout 1987. The turnover in the 11 most traded shares fell 60 per cent. It seems unlikely that this sharp decrease reflected a decline only in speculative trading.
Later, in 1989, the tax base was broadened to include bonds. This, in turn, led to an 85 per cent reduction in bond-trading volume and a 98 per cent reduction of trading volume in bond derivatives. The increase in tax revenues resulting from the broadening was less than 5 per cent of what had been expected.
By 1990, shortly after the last vestiges of the currency controls were abolished in Sweden, more than 50 per cent of the trading in Swedish shares had moved to London. Conversely, once the tax was abolished in December 1991, trading on the Stockholm stock exchange recovered. In 1991, 40 per cent of trading in Swedish shares took place on the Stockholm stock exchange; in 1992, this number had increased to more than 50 per cent.
http://www.ft.com/intl/cms/s/0/b9b40fee-9236-11e2-851f-00144feabdc0.html#axzz3ZlWZhZYV
Initially, the tax rate was 0.5 per cent in connection with the purchase and sale of shares. In mid-1986, the rate was doubled and the tax base was broadened to cover share options and convertibles. The trading volume on the Stockholm stock exchange changed dramatically when the tax was increased. Average turnover fell 30 per cent during the second half of 1986 and throughout 1987. The turnover in the 11 most traded shares fell 60 per cent. It seems unlikely that this sharp decrease reflected a decline only in speculative trading.
Later, in 1989, the tax base was broadened to include bonds. This, in turn, led to an 85 per cent reduction in bond-trading volume and a 98 per cent reduction of trading volume in bond derivatives. The increase in tax revenues resulting from the broadening was less than 5 per cent of what had been expected.
By 1990, shortly after the last vestiges of the currency controls were abolished in Sweden, more than 50 per cent of the trading in Swedish shares had moved to London. Conversely, once the tax was abolished in December 1991, trading on the Stockholm stock exchange recovered. In 1991, 40 per cent of trading in Swedish shares took place on the Stockholm stock exchange; in 1992, this number had increased to more than 50 per cent.
