So, for example, Wells Fargo has about twice the assets of Goldman Sachs, but primarily funds itself with bank deposits and engages in relatively plain consumer and business lending. A more complex firm like Goldman, which relies more heavily on fast-moving capital markets for funding, would thus have more to fear from the risk fee.

Mrs. Clinton’s proposal does not detail the exact scale or structure of the fee, which would require legislation. She envisions it as being substantial enough to have a meaningful impact on banks’ decision making. In other words: billions, not millions, of dollars.

Give regulators more power to break up financial firms. For all the discussion of whether to break up the too-big-to-fail banks in recent years, the actual legal tools that regulators have to do so are limited. Mrs. Clinton proposes granting regulators more explicit power to demand a firm downsize or break up. A campaign fact sheet adds that Mrs. Clinton “would appoint regulators who would both use these new authorities and the substantial authorities they already have to hold firms accountable.”

Dodd-Frank requires that major banks prepare “living wills” that describe the legal details of how they would be unwound in the event of a failure. But this proposed legislation would instead grant regulators more power to determine that, for example, a bank that had repeated major ethics scandals might just be too sprawling and complex to manage and therefore could endanger financial stability.

Regulate “shadow banking” more intensively. While the public debate about financial reform has concentrated on the too-big-to-fail banks, in many ways a bigger driver of the 2008 financial crisis was the “shadow banking” sector — segments of the financial system that resemble banks in important ways but are not regulated like them. It includes money market mutual funds, hedge funds and some parts of the insurance industry.

Her plans for addressing risks in those segments of the shadow banking system are still relatively vague, but she has more specifics on the securities lending and repurchase system, which was a key channel through which the failure of Lehman Brothers and near-failure of the insurer A.I.G. endangered the global financial system in 2008.