In December, I wrote to the heads of six of the country's biggest financial institutions with a simple request: that they voluntarily disclose the financial contributions their companies make to think tanks. This disclosure would help make sure shareholders, policymakers, and the public are aware of efforts by large Wall Street banks to indirectly influence lawmakers and regulators by supporting think tanks' research. Unfortunately, none of the six institutions -- JPMorgan Chase, Bank of America, Citigroup, Wells Fargo, Goldman Sachs, and Morgan Stanley -- has agreed to release this information.

Why not? If they don't make contributions to think tanks that influence public conversations about financial reform issues, it's easy to say so. And if they do make such contributions, why wouldn't they want their shareholders to know how they are spending corporate money?

Why does it matter whether the big financial institutions release this information? Look at the context: Five years ago, reckless activities on Wall Street and regulatory failures in Washington brought our economy to its knees and led to massive government bailouts. Today, we continue to look for ways to ensure that we do not repeat these mistakes and end up in another crisis.

As policymakers work to strengthen oversight of the nation's financial markets, it's essential that we have access to objective, high-quality research, data, and analysis. Private think tanks can be well-suited to provide that kind of research and analysis. Because policymakers often rely on think tanks' research when crafting laws and regulations, it's critical to know whether these organizations are truly independent.

Wall Street banks have the right to express their views to lawmakers and regulators through lobbying, but the law is clear: If they want to influence lawmakers, they must disclose their lobbying expenditures. Yet these same institutions can make huge contributions to think tanks with an eye toward influencing the same lawmakers and keep the whole transaction secret. This is wrong.

If the big banks expect to buy influence when they give money to favored think tanks, then the public has a right to know. If the big banks don't expect to buy influence and are merely making charitable contributions, then their shareholders have a right to know. Either way, there's no excuse for keeping these payments secret.

As lawmakers and regulators work to prevent another financial crisis, I hope the nation's largest financial institutions will voluntarily disclose their contributions to think tanks. Greater transparency will benefit shareholders, policymakers, and, ultimately, the American people.