In addition to bringing back section 16 of the Glass-Steagall Act prohibiting investment banks from gambling with tax payer money, we need to bring back the Tillman Act of 1907 forbidding corporations from funding politics.
Teddy Roosevelt in his 1904 address to Congress said,
"All contributions by corporations to any political committee or for any
political purpose should be forbidden by law; directors should not be
permitted to use stockholders' money for such purposes;"
In 1907 Congress passed the Tillman Act which stated "... it shall be unlawful for any national bank, or any corporation organized
by authority of any laws of Congress, to make a money contribution in
connection with any election to any political office."
The part of corporations funding politics that bothers me is not the presidential election candidates, but to congressmen writing laws for corporations to follow. It's too easy for a corporation to tell a congressman they would like her to support a bill, like extending copyright way beyond its usefulness to encouraging people to create works of art. The congressman gets paid tens of thousands of dollars, and the corporation reaps millions of dollars profit at the expense of the American people.
If she doesn't support the law, the corporation can threaten to fund her opponent.
That's just too much leverage against the interests of the people.