[論文レビュー] The Determinants of Net Interest Margin in the Turkish Banking Sector: Does Bank Ownership Matter?

Fatih Kansoy|ArXiv.org|Jun 4, 2025

Banking stability, regulation, efficiency被引用数 12

ひとこと要約

本論文は、銀行の所有形態に焦点を当て、トルコにおける純利幅（NIM）の決定要因を静的および動的パネル・方法で評価する。銀行固有要因、産業要因、マクロ要因がNIMをどう形作るか、所有形態によって影響が異なるかを検証する。

ABSTRACT

This research presented an empirical investigation of the determinants of the net interest margin in Turkish Banking sector with a particular emphasis on the bank ownership structure. This study employed a unique bank-level dataset covering Turkey`s commercial banking sector for the 2001-2012. Our main results are as follows. Operation diversity, credit risk and operating costs are important determinants of margin in Turkey. More efficient banks exhibit lower margin and also price stability contributes to lower margin. The effect of principal determinants such as credit risk, bank size, market concentration and inflation vary across foreign-owned, state-controlled and private banks. At the same time, the impacts of implicit interest payment, operation diversity and operating cost are homogeneous across all banks

研究の動機と目的

• Identify key bank-specific, industry-specific, and macroeconomic determinants of NIM in Turkey.
• Test whether intercepts and coefficient estimates differ across bank ownership forms (foreign, state, private).
• Provide dynamic insights into NIM persistence using panel data methods.
• Assess robustness of results using fixed effects, random effects, and system GMM estimations.

提案手法

• Use bank-level quarterly data for 23 Turkish commercial banks from 2001Q4 to 2012Q1.
• Estimate NIM as a function of pure interest margin components, bank-specific determinants, and macro/market variables.
• Apply POLS, Fixed Effects, Random Effects, and dynamic GMM (system GMM) to address endogeneity and dynamics.
• Perform Breusch-Pagan LM test, Hausman test, Sargan test, and Arellano-Bond tests to choose estimation method and validate instruments.

実験結果

リサーチクエスチョン

• RQ1 What are the key determinants of Net Interest Margin in the Turkish banking sector?
• RQ2 Do the intercepts and the effects of determinants differ by bank ownership form (foreign, state-controlled, private)?
• RQ3 Are there dynamic (lagged) effects in NIM that persist over time, and how robust are these findings to different econometric specifications?
• RQ4 How do macroeconomic conditions (GDP growth, inflation) and market structure (HHI) influence NIM in Turkey?
• RQ5 How do operating efficiency, credit risk, and diversification (operation diversity) relate to NIM in Turkish banks?

主な発見

変数	POLS	FE	RE	GMM
L.NIM	-	-	-	0.228*** (0.0258)
L2.NIM	-	-	-	-0.0122*** (0.00223)
RA	0.0899***	0.0983***	0.0899***	0.0115 (0.00777)
RBD	-0.0164**	-0.0218***	-0.0164**	-0.0343*** (0.00524)
OC	0.134**	0.153**	0.134**	0.0817*** (0.0107)
LOGTA	0.413***	0.834	0.413***	0.00962 (0.147)
LQR	-5.98E-05	-0.00985*	-5.98E-05	-0.002 (0.00176)
MNGMT	-0.00381***	-0.00344***	-0.00381***	-0.00620*** (0.00023)
IIP	0.508***	0.541***	0.508***	0.369*** (0.0138)
DPZTG	-0.000503***	-0.000536***	-0.000503***	-0.000344*** (0.000017)
DVRSTY	-0.228**	-0.304***	-0.228**	-0.379*** (0.0489)
HHI	0.0528	0.181	0.0528	0.221 (0.151)
GDP	-0.0294**	-0.0262*	-0.0294**	-0.00215 (0.00205)
INF	0.0394***	0.0445***	0.0394***	0.0295*** (0.00599)
CONSTANT	-3.546	-7.657	-3.546	-1.354 (2.261)

• Operation diversity, credit risk, and operating costs are important determinants of NIM in Turkey.
• More efficient banks exhibit lower NIM, and price stability contributes to lower margin.
• The effects of key determinants such as credit risk, bank size, market concentration, and inflation vary across foreign-owned, state-controlled, and private banks.
• Implicit interest payment, operation diversity, and operating cost effects are homogeneous across ownership groups.
• Dynamic estimation shows lagged NIM and certain regressors are statistically significant, indicating persistence over time.