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Economic SYNOPSES
short essays and reports on the economic issues of the day
2010 ■ Number 1

The Evolving Size Distribution of Banks
Silvio Contessi, Economist
undamental issues about bank size and the systemic
risk implications of so-called too-big-to fail policies
are heated topics of discussion for researchers, policymakers, and the press alike.1 However, significant changes
in size distribution of banks have been occurring since at
least the 1980s and 1990s, when the structure of the banking industry began to evolve following regulatory changes
such as the Riegle-Neal Interstate Banking and Branching
Efficiency Act of 1994 and the Gramm-Leach-Bliley
Financial Services Modernization Act of 1999.
To document the changes in the size distribution of
banks, we study total assets of commercial banks using the
public Call Reports for three selected dates: 1987:Q2,
1998:Q2, and 2009:Q2.2 During these 22 years the number
of banks fell from 15,168 to 10,169 and then to 7,744 after
progressive concentration of the industry and bank failures,
particularly during the Savings and Loan Crisis of the late
1980s and early 1990s and the current financial crisis.
We can use total assets at the end of these three quarters to compare the distribution over time. We deflate
each bank’s assets and then rescale them, dividing by the
total assets each year relative to 2005. The chart plots the
distribution using the logarithm of assets on the horizontal axis and the frequency on the vertical axis. Each curve
represents the bank size distribution for one of the three
study years.
Many key facts can be noticed using this chart. First,
the total number of banks in the United States has substantially decreased, although the number is still considered
large by international standards. Second, over time the
increase in the number of relatively larger banks stretched
the tail of the distribution to the right, a common measure
of the asymmetry of a distribution around its mean—the
skewness of the distribution—increased from 0.92 in 1987
to 0.95 in 2009. Third, the largest banks own an even larger
share of total assets, making the right tail of the distribution
even thicker, a measure of the thickness of a distribution
tail—the kurtosis—has increased from 5.4 in 1987 to 6.7
in 2009. If we dropped the largest 50 banks, the kurtosis

F

would increase by much less and the skewness would fall
instead of increasing.

If limiting the size of large banks were
considered appropriate to reduce
systemic risk, it would be a clear
change of direction relative to the
long-term evolution of the industry.
Hence, the flattening of the bank size distribution is
part of a long-term trend and may have led to a more concentrated industry with larger average-size and big banks
independently of the recent financial crisis and the concurrent policy interventions. The current debate on too big to
fail is important because it clarifies the tension between
profitability, propensity to take risk, economies of scale,

Size Distribution of Bank Size over Time
Frequency
2,800

1987
1998
2009

2,400
2,000
1,600
1,200
800
400
0
4

6

8

10

12

14

Total Assets, Log Scale

16

18

20

Economic SYNOPSES

Federal Reserve Bank of St. Louis

and economies of diversification on the one hand, and the
competitive and systemic risks imposed by fewer larger
yet more complex players on the other hand. However, if
limiting the size of large banks were considered appropriate
to reduce systemic risk, it would be a clear change of direction relative to the long-term evolution of the industry. ■

2

1

Bullard, James. “The Fed and the Coming Redefinition of Government
Regulation.” Presented at the Business Today International Conference: “Weathering
the Storm: The Challenges and Opportunities of a Global Slowdown,” New York,
November 22, 2009;
http://research.stlouisfed.org/econ/bullard/BullardPrincetonFINAL.pdf.

2

For a more extensive analysis of the changes in the size distribution, see Janicki,
Hubert P. and Prescott, Edward S. “Changes in the Size Distribution of U.S. Banks:
1960-2005.” Federal Reserve Bank of Richmond Economic Quarterly, Fall 2006,
92(4), pp. 291-316;
www.richmondfed.org/publications/research/economic_quarterly/2006/fall/pdf/
janicki_prescott.pdf.

Posted on January , 2010
Views expressed do not necessarily reflect official positions of the Federal Reserve System.

research.stlouisfed.org