• Group says levy would cause Dow Jones to plunge • Study claims seven out of 10 people oppose idea America’s leading business advocacy group, the US chamber of commerce, has slammed proposals for a Robin Hood tax on financial transactions by claiming that a levy would cause the Dow Jones Industrial Average to plunge by 12.5%, and that seven out of 10 people oppose the idea. Gordon Brown has led calls for an international Tobin tax intended to curb reckless speculation in the financial industry and the European parliament voted overwhelmingly this week to develop plans for a tax to be presented to the G20 in June. In Washington, backbench Democratic lawmakers have put forward potential legislation for a levy of up to 0.25% on trades that would raise an estimated $150bn (£100bn) annually.