Hillary Clinton unveiled a plan that aims to tackle excessive risk-taking in the financial sector and calls for breaking up too-big-to-fail banks.
The proposal, laid out Thursday, would impose a risk fee on financial firms "that are too large and too risky to manage" and require them to reorganize, downsize or break apart, the Democratic presidential hopeful said.
"I have a plan to build on the progress we've made under President Obama and do just that," Clinton said in a statement. "We can't go back to the days when Wall Street could write its own rules."
The announcement come in advance of Tuesday's first Democratic presidential debate.
The proposals also called for raising the fines that regulators could impose on corporations and their executives, and imposing a new tax on high-frequency trading (HFT).
"These sound like much more meaningful reforms than some of the things she has suggested earlier," said former Federal Deposit Insurance Corp Chair Sheila Bair, currently president of Washington College, in Chestertown, Maryland.
Clinton's HFT tax would target securities transactions with excessive levels of order cancellations, which her campaign said unnecessarily burdens markets and enables unfair and abusive trading strategies.
HFT firms say their trading adds needed liquidity and that such a tax would end up making the markets less efficient and more expensive for all investors.
Earlier this week, Clinton spoke out against the Trans-Pacific Partnership, the 12-nation trade pact that she boosted as secretary of state and that liberals in the Democratic Party have vehemently opposed.
—Reuters contributed to this report.