Size, Efficiency, Market Power, and Economies of Scale in the African Banking Sector

Forthcoming: Financial Innovation

A G D I Working Paper No. WP/18/056

29 Pages Posted: 3 Jan 2019

See all articles by Simplice Asongu

Simplice Asongu

African Governance and Development Institute

Nicholas Odhiambo

University of South Africa - Department of Economics

Date Written: December 18, 2018

Abstract

There is a growing body of evidence that interest rate spreads in Africa are higher for big banks compared to small banks. One concern is that big banks might be using their market power to charge higher lending rates as they become larger, more efficient, and unchallenged. In contrast, several studies found that when bank size increases beyond certain thresholds, diseconomies of scale are introduced that lead to inefficiency. In that case, we also would expect to see widened interest margins. This study examines the connection between bank size and efficiency to understand whether that relationship is influenced by exploitation of market power or economies of scale. Using a panel of 162 African banks for 2001–2011, we analyzed the empirical data using instrumental variables and fixed effects regressions, with overlapping and non-overlapping thresholds for bank size. We found two key results. First, bank size increases bank interest rate margins with an inverted U-shaped nexus. Second, market power and economies of scale do not increase or decrease the interest rate margins significantly. The main policy implication is that interest rate margins cannot be elucidated by either market power or economies of scale. Other implications are discussed.

Keywords: Sub-Saharan Africa; Banks; Lending Rates; Efficiency; Quiet Life Hypothesis; Competition

JEL Classification: E42; E52; E58; G21; G28

Suggested Citation

Asongu, Simplice and Odhiambo, Nicholas, Size, Efficiency, Market Power, and Economies of Scale in the African Banking Sector (December 18, 2018). Forthcoming: Financial Innovation , A G D I Working Paper No. WP/18/056 , Available at SSRN: https://ssrn.com/abstract=3303105 or http://dx.doi.org/10.2139/ssrn.3303105

Simplice Asongu (Contact Author)

African Governance and Development Institute ( email )

P.O. Box 8413
Yaoundé, 8413
Cameroon

Nicholas Odhiambo

University of South Africa - Department of Economics ( email )

PO Box 392
Pretoria, 0003
South Africa

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