Hillary Clinton has vowed to impose a high-frequency trading tax as part of a Wall Street reform package if she becomes president.
With socialist Bernie Sanders gathering momentum in the polls, Clinton has set out her ideas for sweeping reforms of the financial system in a bid to win over left wing support and secure the Democratic nomination.
Clinton, who has won huge financial backing from Wall Street, says that the growth of high-frequency trading has "unnecessarily burdened our markets and enabled unfair and abusive trading strategies".
To tackle this, she is promising to impose a tax that would hit HFT strategies "involving excessive levels of order cancellations, which make our markets less stable and less fair".
In addition, Clinton has taken aim at dark pools, promising to reforms that will "ensure equal access to markets and information, increase transparency, and minimize conflicts of interest".
Another plank of the former First Lady's Wall Street programme sees a greater emphasis from regulators on ensuring banks are ready for cyber attacks. Cyber-preparedness will become a significant part of assessments, while information sharing between government and the private sector will be boosted.