Capital Requirements For Banks Are Needed But Costly—Only Limited Increases Are Called For

About the Author

William R. Cline has been a senior fellow at the Peterson Institute for International Economics since 1981. During 1996–2001 while on leave from the Institute, he was deputy managing director and chief economist of the Institute of International Finance (IIF) in Washington, DC. From 2002 through 2011 he held a joint appointment with the Peterson Institute and the Center for Global Development, where he is currently senior fellow emeritus. Before joining the Peterson Institute, he was senior fellow, the Brookings Institution (1973–81); deputy director of development and trade research, office of the assistant secretary for international affairs, US Treasury Department (1971–73); Ford Foundation visiting professor in Brazil (1970–71); and lecturer and assistant professor of economics at Princeton University (1967–70). He is the author of several books, including Managing the Euro Area Debt Crisis (2014) and Financial Globalization, Economic Growth, and the Crisis of 2007–09 (2010).

Washington—A new book published by the Peterson Institute for International Economics argues banking regulations after the financial crisis have made banking systems safer, but overall capital requirements under Basel III remain inadequate. In The Right Balance for Banks: Theory and Evidence on Optimal Capital Requirements, William R. Cline, a renowned expert on financial markets and senior fellow at the Peterson Institute, argues that the appropriate level of capital for banks to hold for optimal tradeoff between economic growth and financial stability is 7 to 8 percent of total assets. Unduly high requirements for equity capital in banks could cause higher lending rates, less formation of capital stock throughout the economy, and therefore lower productive capacity, he concludes.

Cline’s study, one of several analyses of financial stability published by PIIE since the crisis of 2008–09, reviews the extensive literature on banking crises, regulations, and their impact on capital formation and economic growth. It looks indepth at the multilateral voluntary framework on bank capital adequacy known as Basel III, established in 2010–11, which raised the amount of equity capital that banks must hold. The Basel III rules only require the largest banks to hold 9.5 percent of risk-weighted assets in equity capital. Cline calculates instead that equity capital should be 12 to 14 percent of risk-weighted assets, corresponding to 7 to 8 percent of total assets. While an increase, this assessment is in contrast to some academics’ calls for far higher bank capital, ranging from 15 to 25 percent of total assets.

The Right Balance for Banks makes a major contribution to the policy debate by providing a rigorous, replicable, and transparent calculation of the optimal capital requirement for banks. It first considers whether and how much banks would have to raise lending rates if forced to hold more capital. Cline tests an oft-invoked theory from financial economics (Modigliani-Miller) that implies there would be no cost to raising capital because investors would be satisfied with lower returns thanks to lower leverage and lesser risk. Cline instead finds that, in practice, slightly less than half of this risk-reduction offset would occur. He then applies a consensus estimate of the influence of bank capital on the risk of banking crises, combined with well-established relationships between output and capital stock, to calculate the point at which higher costs to the economy from higher bank capital requirements are just offset by lower expected crisis damage.

Cline’s book also discusses related questions such as whether “too big to fail” causes large banks to take excessive risk and whether there are important economies of scale in banking. He questions recent studies that argue the financial sector is curbing growth because it has become excessively large as confusing correlation with causation.

“After the Great Recession, a lot of economists understandably argued that excessive finance is dangerous and that we have to at least double bank capital levels, but did so without rigorously and quantitively assessing the potential cost to the economy of doing so.” said Adam S. Posen, PIIE president. “Bill acutely realizes that there is an economic cost of over-capitalization and curbing bank credit. His analysis derives and estimates an optimal level of financial regulation that he argues is sufficient to safeguard the global financial system from another financial crisis, without unnecessary brakes on economic growth.”

The Right Balance for Banks: Theory and Evidence on Optimal Capital Requirements
William R. Cline
ISBN paper 978-0-88132-721-2
June 2017 • 242 pp. • $23.95



The Peterson Institute for International Economics is a private, nonprofit institution for rigorous, intellectually open, and indepth study and discussion of international economic policy. Its purpose is to identify and analyze important issues to make globalization beneficial and sustainable for the people of the United States and the world, and then to develop and communicate practical new approaches for dealing with them. The Institute is widely viewed as nonpartisan. Its work is funded by a highly diverse group of philanthropic foundations, private corporations, and interested individuals, as well as income on its capital fund. About 35 percent of the Institute’s resources in its latest fiscal year were provided by contributors from outside the United States. Visit to view a list of all financial supporters.

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