Clinton to propose increasing capital gains taxes

In remarks on Facebook, Clinton also expanded on a promise to pursue criminal prosecution of bad actors on Wall Street, saying she would strengthen the power of government regulators and raise caps on compensation for financial whistleblowers.

Clinton's tax proposal marks a shift from her 2008 campaign, when she promised not to raise capital gains rates higher than the 20 percent bracket established during her husband's administration.

Over his time in the White House, President Barack Obama has raised the capital gains rate for top earners to 23.8 percent — fulfilling a campaign promise to raise the tax.

Last month, Neera Tanden, the head of the liberal Center for American Progress and a prominent Clinton adviser, proposed a "sliding-scale" capital gains tax that would drop the rate charged the longer the security is held.

"Once an investor holds a share past the one-year mark, the tax code provides no incentives to maintain the position any longer," Tanden wrote, in a report co-authored by investment banker Blair Effron, co-founder of Centerview Partners.