1 Introduction
2 Background and theoretical framework
3 Hypothesis development
3.1 Market valuations of busy board of directors in Islamic and conventional banks
3.2 Market valuations of busy SSB in Islamic banks
4 Data and sample
Country | Observations (Islamic banks) | Observations (conventional banks) | Observations (full sample) | % (Islamic banks) | % (conventional banks) | % (full sample) |
---|---|---|---|---|---|---|
Bahrain | 30 | 30 | 60 | 20.00 | 12.71 | 15.54 |
Bangladesh | 36 | 44 | 80 | 24.00 | 18.64 | 20.73 |
Egypt | 3 | 9 | 12 | 2.00 | 3.81 | 3.11 |
Indonesia | 6 | 66 | 72 | 4.00 | 27.97 | 18.65 |
Jordan | 12 | 29 | 41 | 8.00 | 12.29 | 10.62 |
Kuwait | 3 | 12 | 15 | 2.00 | 5.09 | 3.89 |
Pakistan | 24 | 6 | 30 | 16.00 | 2.54 | 7.77 |
Qatar | 18 | 24 | 42 | 12.00 | 10.17 | 10.88 |
Saudi Arabia | 6 | 6 | 12 | 4.00 | 2.54 | 3.11 |
UAE | 6 | 6 | 12 | 4.00 | 2.54 | 3.11 |
Oman | 6 | 4 | 10 | 4.00 | 1.70 | 2.59 |
Bank-year observations | 150 | 236 | 386 | 100 | 100 | 100 |
Number of banks | 27 | 43 | 70 | − | − | − |
5 Methodology
5.1 Measures of the bank market value
5.2 Measures of board busyness
5.3 Empirical models
Variables | Abbreviations | Definitions |
---|---|---|
Tobin’s Q | lnQ | Natural logarithm of Tobin’s Q ratio, which is calculated by the sum of a bank total debt and market value of equity, divided by its book value of total assets. The market value of equity is computed as the number of outstanding shares multiplied by the stock prices |
% Busy outside directors | %BBOD | Percentage of busy independent directors on the board (%), calculated as number of independent directors serving on two or more outside firms divided by number of independent directors on the board |
% Busy Shari’ah advisors | %BSSB | Percentage of busy Shari’ah advisors on the board, calculated as number of Shari’ah advisors serving on two or more outside firms divided by the number of Shari’ah advisors on the board |
Board of directors size | LogBSIZE | Natural logarithm of the total number of board of directors’ members |
Board independence | %INDEP | Percentage of independent non-executive directors on the board of directors |
Bank size | LogTA | Natural logarithm of total assets of a bank at the end of the year |
Capital expenditure/total assets | CAPEX/ASSETS | The ratio of capital expenditures to assets |
Cash/total assets | CASH/ASSETS | The ratio of cash to total assets |
Leverage | LEV | Bank leverage, measured by total liability divided by Equity |
Big 4 audited | BIG4 | Dummy variable: 1 if the bank is audited by Big4 company, 0 otherwise. |
Herfindahl–Hirschman Index | HHI | The Herfindahl–Hirschman Index as a measure of bank concentration. Higher HHI shows higher bank concentration. It is calculated by the square of the sum of the ratio of total assets of each bank-year to total assets of all banks each year. It has a value between zero and one |
GDP per capita | GDPCAPITA | Annual Gross Domestic Products (GDP) over capita (population) |
Country-Level Governance Index | COUNTRY_GOV | Estimated as the average of six governance measures including the regulatory quality, rule of law, control of corruption, political stability, governance effectiveness, and the voice and accountability. Each component is estimated by ranging from − 2.5 (weak) to + 2.5 (strong) |
Islamic bank | ISLAMIC | Dummy variable: 1 if the bank is Islamic, 0 for a conventional bank |
Return on assets | ROA | Net income over total assets |
Return on equity | ROE | Net income over total equity |
The average number of outside directorships of outside directors | ABOD | Average outside directorships per outside director |
The average number of outside directorships of Shari’ah advisors | ASSB | Average outside directorships per Shari’ah advisors |
Board of directors compensation | BODC/NI | Board of directors’ compensation deflated by net income |
SSB compensation | SSB/NI | SSB compensation deflated by net income |
SSB size | LogSSBSize | Natural logarithm of the total number of Shari’ah advisors |
Bank age | LogAge | Natural logarithm of the difference between the sample year and the year of a bank’s first appearance |
Bank risk-taking | LogZscore | The distance to default, calculated as the natural logarithm of a sum of the return on assets (ROA) plus Capital Assets Ratio (CAR) scaled by the standard deviation of ROA |
5.4 Descriptive statistics
Full sample | Islamic banks sample mean | Conventional banks sample mean | Two-sample t test (two-tailed) | ||||||
---|---|---|---|---|---|---|---|---|---|
Variables | N | Mean | Median | Std. | Min | Max | |||
lnQ | 386 | 0.235 | 0.029 | 1.028 | − 0.219 | 6.558 | 0.259 | 0.220 | − 0.342 |
%BBOD | 386 | 0.479 | 0.5 | 0.377 | 0 | 1 | 0.434 | 0.509 | 1.908* |
%BSSB | 150 | 0.778 | 1 | 0.299 | 0.111 | 1 | 0.778 | − | − |
BSIZE | 386 | 9.544 | 9 | 3.705 | 3 | 25 | 10.647 | 8.843 | − 4.512*** |
%INDEP | 386 | 0.348 | 0.333 | 0.237 | 0 | 1 | 0.327 | 0.362 | 1.322 |
LogTA | 386 | 15.407 | 15.427 | 1.287 | 11.999 | 18.047 | 15.228 | 15.522 | 2.196** |
CAPEX/ASSETS | 386 | 0.316 | 0.207 | 0.418 | 0 | 3.685 | 0.300 | 0.327 | 0.616 |
CASH/ASSETS | 386 | 0.091 | 0.080 | 0.059 | 0.004 | 0.420 | 0.102 | 0.084 | − 2.701*** |
LEV | 386 | 8.039 | 7.775 | 3.774 | − 4.210 | 19.998 | 8.283 | 7.883 | − 0.945 |
BIG4 | 386 | 0.717 | 1 | 0.451 | 0 | 1 | 0.620 | 0.780 | 3.320*** |
HHI | 386 | 0.142 | 0.109 | 0.095 | 0.058 | 0.672 | 0.159 | 0.131 | − 2.573** |
GDPCAPITA | 386 | 18636 | 3700 | 26,893 | 760 | 96,732 | − | − | − |
COUNTRY_GOV | 386 | − 0.286 | − 0.212 | 0.526 | − 1.181 | 0.737 | − | − | − |
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) | (11) | (12) | |
---|---|---|---|---|---|---|---|---|---|---|---|---|
Panel A: Pairwise correlation matrix for Islamic banks | ||||||||||||
1. %BBOD | 1 | |||||||||||
2. %BSSB | 0.124 | 1 | ||||||||||
3. LogBSIZE | 0.076 | − 0.692* | 1 | |||||||||
4. %INDEP | 0.418* | 0.306* | − 0.285* | 1 | ||||||||
5. LogTA | 0.008 | 0.213* | − 0.032 | 0.296* | 1 | |||||||
6. CAPEX/ASSETS | 0.043 | 0.027 | 0.038 | 0.077 | − 0.146 | 1 | ||||||
7. CASH/ASSETS | 0.176* | − 0.136 | 0.420* | − 0.067 | 0.075 | 0.125 | 1 | |||||
8. LEV | 0.031 | − 0.222* | 0.288* | − 0.231* | 0.298* | − 0.057 | 0.350* | 1 | ||||
9. BIG4 | 0.256* | 0.592* | − 0.396* | 0.540* | 0.496* | − 0.017 | − 0.263* | − 0.378* | 1 | |||
10. HHI | − 0.125 | 0.238* | − 0.261* | − 0.130 | 0.085 | 0.093 | 0.042 | − 0.012 | 0.099 | 1 | ||
11. GDPCAPITA | − 0.153 | 0.383* | − 0.144 | 0.126 | 0.465* | − 0.022 | − 0.349* | − 0.333* | 0.528* | 0.092 | 1 | |
12. COUNTRY_GOV | 0.071 | 0.470* | − 0.126* | 0.407* | 0.406* | − 0.021 | − 0.144 | − 0.418* | 0.649* | − 0.074 | 0.628* | 1 |
Panel B: Pairwise correlation matrix for conventional banks | ||||||||||||
1. %BBOD | 1 | |||||||||||
2. LogBSIZE | 0.311* | 1 | ||||||||||
3. %INDEP | 0.020 | − 0.497* | 1 | |||||||||
4. LogTA | − 0.015 | − 0.001 | 0.141* | 1 | ||||||||
5. CAPEX/ASSETS | − 0.042 | − 0.008 | − 0.027 | − 0.418* | 1 | |||||||
6. CASH/ASSETS | − 0.012 | − 0.038 | − 0.076 | − 0.133* | 0.061 | 1 | ||||||
7. LEV | − 0.119 | 0.022 | − 0.095 | − 0.185* | − 0.109 | 0.294* | 1 | |||||
8. BIG4 | 0.166* | − 0.083 | 0.230* | 0.426* | − 0.143* | − 0.237* | − 0.540* | 1 | ||||
9. HHI | 0.181* | 0.149* | − 0.077 | 0.096 | − 0.096 | − 0.095 | − 0.287* | 0.319* | 1 | |||
10. GDPCAPITA | 0.101 | − 0.053 | 0.008 | 0.377* | − 0.204* | − 0.336* | − 0.381* | 0.324* | 0.351* | 1 | ||
11. COUNTRY_GOV | 0.164* | − 0.141* | 0.230* | 0.447* | − 0.212* | − 0.238* | − 0.567* | 0.550* | 0.294* | 0.601* | 1 |
6 Empirical results
6.1 Market valuations of busy boards of directors in Islamic and conventional banks
Variables | Panel A: Full sample (IBs and CBs together) | Panel B: Islamic banks (IBs) | Panel C: Conventional banks (CBs) | |
---|---|---|---|---|
lnQ (1) | lnQ (2) | lnQ (3) | lnQ (4) | |
%BBOD | 2.950*** (0.000) | 0.285 (0.109) | 0.427 (0.104) | 1.826*** (0.000) |
%BSSB | − 1.365*** (0.007) | |||
LogBSIZE | − 0.391*** (0.004) | − 0.117* (0.096) | − 0.159* (0.084) | 0.152 (0.192) |
INDEP | − 1.006*** (0.000) | − 0.233*** (0.004) | − 0.347*** (0.004) | − 0.786*** (0.000) |
LogTA | 0.048 (0.643) | 0.048* (0.087) | 0.129** (0.050) | − 0.278*** (0.003) |
CAPEX/ASSETS | 0.003 (0.561) | 0.002 (0.420) | 0.005 (0.100) | − 0.002 (0.745) |
CASH/ASSETS | − 2.045*** (0.000) | − 0.713*** (0.007) | − 0.673** (0.036) | − 1.349*** (0.007) |
LEV | − 0.004 (0.719) | 0.012** (0.049) | 0.017** (0.047) | 0.010 (0.405) |
BIG4 | − 0.617*** (0.002) | − 0.147* (0.094) | − 0.223* (0.094) | − 0.333*** (0.009) |
HHI | 0.446 (0.125) | − 0.015 (0.869) | 0.177 (0.190) | 0.524 (0.131) |
GDPCAPITA | − 0.014*** (0.005) | 0.005** (0.011) | 0.003 (0.339) | − 0.008** (0.040) |
COUNTRY_GOV | 0.496** (0.033) | − 0.028 (0.812) | 0.042 (0.777) | 0.395** (0.034) |
ISLAMIC | 0.091 (0.735) | |||
Constant | 0.465 (0.769) | − 0.350 (0.581) | − 0.247 (0.808) | 3.379** (0.025) |
Year fixed effect | YES | YES | YES | YES |
Bank fixed effect | YES | YES | YES | YES |
Observations | 386 | 150 | 150 | 236 |
Adjusted R2 | 0.748 | 0.994 | 0.990 | 0.882 |
Chi2 LM statistics (p value) Sargan test (p value) | 3164*** 0.000 0.414 | 2645*** 0.046 0.151 | 1423*** 0.000 0.199 | 4480*** 0.000 0.376 |
%BBOD = %BSSB (F-test) | 0.000 |
6.2 Market valuations of busy SSB in Islamic banks
7 Additional testing
7.1 Tests for the effect of busy boards on bank agency relationships
Variables | Panel A: Islamic banks (IBs) | Panel B: Conventional banks (CBs) |
---|---|---|
CASH/ASSETS (1) | CASH/ASSETS (2) | |
%BBOD | 0.033* (0.091) | − 0.099*** (0.000) |
%BSSB | 0.211** (0.030) | |
LogBSIZE | 0.008 (0.733) | − 0.010 (0.514) |
%INDEP | − 0.041* (0.097) | 0.020 (0.290) |
LogTA | 0.046** (0.022) | 0.024* (0.084) |
LogAge | − 0.056** (0.047) | − 0.016 (0.476) |
LogZscore | − 0.043** (0.021) | 0.026* (0.081) |
ROAA | − 0.001 (0.857) | 0.012* (0.061) |
GDPCAPITA | 0.003 (0.859) | − 0.001*** (0.004) |
COUNTRY_GOV | 0.003 (0.933) | 0.053* (0.056) |
LogSSBSize | 0.068* (0.080) | |
Constant | − 0.512 (0.232) | − 0.321 (0.241) |
Year fixed effect | YES | YES |
Bank fixed effect | YES | YES |
Observations | 150 | 236 |
Overall R2 | 0.804 | 0.543 |
Wald Chi2 | 700*** | 463*** |
LM statistics (p value) | 0.000 | 0.000 |
Sargan test (p value) | 0.765 | 0.832 |
%BBOD = %BSSB (F-test) | 0.002 |
7.2 Tests for the influence of boards compensation on busyness
Variables | Panel A: Full sample (IBs and CBs together) | Panel B: Islamic banks (IBs) | Panel C: Conventional banks (CBs) | |
---|---|---|---|---|
%BBOD (1) | %BBOD (2) | %BSSB (3) | %BBOD (4) | |
BODC/NI | − 0.155** (0.024) | 0.345 (0.376) | − 0.131** (0.049) | |
SSBC/NI | 0.454** (0.019) | |||
LogBSIZE | 0.381*** (0.000) | 0.225** (0.015) | − 0.115*** (0.007) | 0.470*** (0.000) |
%INDEP | 0.576*** (0.000) | 0.706*** (0.000) | 0.184*** (0.000) | 0.480*** (0.000) |
ROAA | − 0.007 (0.239) | − 0.005 (0.531) | − 0.008*** (0.003) | 0.005 (0.797) |
LogTA | − 0.031* (0.068) | − 0.010 (0.727) | 0.011 (0.383) | − 0.042** (0.037) |
GDPCAPITA | 0.001 (0.304) | − 0.002*** (0.010) | 0.001** (0.038) | 0.002** (0.017) |
ISLAMIC | − 0.144*** (0.000) | |||
LogSSBSize | − 0.470*** (0.000) | |||
Constant | − 0.032 (0.901) | − 0.154 (0.717) | 1.529*** (0.000) | − 0.044 (0.893) |
Year fixed effect | YES | YES | YES | YES |
Bank fixed effect | YES | YES | YES | YES |
Observations | 386 | 150 | 150 | 236 |
Overall R2 | 0.168 | 0.262 | 0.793 | 0.177 |
Wald Chi2 | 11*** | 17*** | 94*** | 7*** |
8 Sensitivity and robustness checks
8.1 Propensity score matching approach
Average treatment effects | Panel A: Full sample (IBs and CBs together) | Panel B: Islamic banks (IBs) | Panel C: Conventional banks (CBs) | ||||||
---|---|---|---|---|---|---|---|---|---|
Treated | Non-treated | Δ (t-stat) | Treated | Non-treated | Δ (t-stat) | Treated | Non-treated | Δ (t-stat) | |
1-Year window | − 0.018 | − 0.057 | 0.039* (1.95) | − 0.014 | − 0.043 | 0.029 (1.68) | − 0.022 | − 0.150 | 0.127* (1.30) |
2-Year window | − 0.026 | − 0.111 | 0.087*** (2.90) | 0.002 | 0.045 | − 0.043** (− 2.59) | − 0.037 | − 0.143 | 0.106* (1.75) |
3-Year window | − 0.030 | − 0.120 | 0.090** (2.08) | − 0.021 | − 0.009 | − 0.012 (− 0.29) | − 0.056 | − 0.092 | 0.036* (1.90) |
8.2 Possible non-linear relationship between busy boards and bank value
Variables | Panel A: Islamic banks (IBs) | Panel B: Conventional banks (CBs) |
---|---|---|
lnQ (1) | lnQ (2) | |
%BBOD | 1.098 (0.103) | 0.742** (0.049) |
(%BBOD)2 | − 0.913* (0.095) | 0.963*** (0.007) |
%BSSB | 5.637*** (0.000) | |
(%BSSB)2 | − 3.792*** (0.000) | |
Bank-level controls | YES | YES |
Country-level controls | YES | YES |
Constant | − 4.471*** (0.002) | 3.402** (0.040) |
Year fixed effect | YES | YES |
Bank fixed effect | YES | YES |
Observations | 150 | 236 |
Adjusted R2 | 0.987 | 0.888 |
Chi2 LM statistics (p value) Sargan test (p value) | 1550*** 0.000 0.250 | 3908*** 0.000 0.405 |
%BBOD = %BSSB (F-test) | 0.000 |
8.3 Using accounting-based measures for bank performance
Variables | Panel A: Islamic banks (IBs) | Panel B: Conventional banks (CBs) | ||
---|---|---|---|---|
ROA (1) | ROE (2) | ROA (3) | ROE (4) | |
%BBOD | 1.741 (0.118) | 2.020 (0.243) | 0.792*** (0.000) | 0.626*** (0.000) |
%BSSB | − 3.012* (0.069) | − 3.274* (0.071) | ||
LogBSIZE | − 0.804** (0.014) | − 1.079*** (0.008) | 0.071 (0.121) | 0.067 (0.101) |
INDEP | − 0.251 (0.531) | − 0.426 (0.341) | − 0.239*** (0.000) | − 0.207*** (0.000) |
LogTA | − 0.396 (0.102) | − 0.020 (0.945) | − 0.057 (0.120) | − 0.040 (0.223) |
CAPEX/ASSETS | 0.002 (0.806) | 0.008 (0.458) | − 0.001 (0.914) | 0.002 (0.773) |
CASH/ASSETS | 0.782 (0.489) | 0.230 (0.870) | − 0.398** (0.049) | − 0.359** (0.043) |
LEV | − 0.078*** (0.008) | − 0.056* (0.087) | − 0.001 (0.861) | 0.007* (0.072) |
BIG4 | 0.687 (0.123) | 0.287 (0.548) | − 0.103** (0.039) | − 0.081* (0.067) |
HHI | 0.469 (0.276) | 0.652 (0.175) | − 0.063 (0.600) | − 0.017 (0.868) |
GDPCAPITA | − 0.001 (0.959) | − 0.001 (0.925) | − 0.007*** (0.000) | − 0.005*** (0.000) |
COUNTRY_GOV | − 0.441 (0.382) | − 0.498 (0.357) | 0.223*** (0.003) | 0.133** (0.038) |
Constant | 10.545*** (0.005) | 5.573 (0.211) | 0.537 (0.362) | 0.264 (0.614) |
Year fixed effect | YES | YES | YES | YES |
Bank fixed effect | YES | YES | YES | YES |
Observations | 150 | 150 | 236 | 236 |
Adjusted R2 | 0.543 | 0.400 | 0.504 | 0.469 |
Chi2 LM statistics (p value) Sargan test (p value) | 100*** 0.000 0.260 | 68*** 0.000 0.236 | 379*** 0.000 0.105 | 238*** 0.000 0.143 |
%BBOD = %BSSB (F-test) | 0.000 | 0.000 |
8.4 Using alternative measures for busy boards
Variables | Panel A: Islamic banks (IBs) | Panel B: Conventional banks (CBs) |
---|---|---|
lnQ (1) | LnQ (2) | |
ABOD | − 0.046 (0.349) | 0.080*** (0.000) |
ASSB | − 1.256** (0.049) | |
LogBSIZE | − 0.603** (0.014) | 0.100 (0.129) |
INDEP | − 0.715** (0.028) | − 0.254*** (0.003) |
LogTA | − 0.426 (0.125) | − 0.168*** (0.004) |
CAPEX/ASSETS | − 0.032 (0.120) | − 0.001 (0.737) |
CASH/ASSETS | 3.317 (0.101) | − 0.107 (0.750) |
LEV | − 0.062 (0.137) | 0.003 (0.643) |
BIG4 | − 2.435** (0.049) | − 0.076 (0.286) |
HHI | − 1.326* (0.065) | 0.428** (0.024) |
GDPCAPITA | 0.002 (0.797) | − 0.006** (0.029) |
COUNTRY_GOV | 0.362 (0.401) | 0.196* (0.069) |
Constant | 28.750** (0.049) | 2.221** (0.024) |
Year fixed effect | YES | YES |
Bank fixed effect | YES | YES |
Observations | 150 | 236 |
Adjusted R2 | 0.823 | 0.978 |
Chi2 LM statistics (p value) Sargan test (p value) | 2625*** 0.000 0.114 | 1082*** 0.000 0.157 |
%BBOD = %BSSB (F-test) | 0.000 |
8.5 Using first-differenced regression models
Variables | Panel A: Islamic banks (IBs) | Panel B: Conventional banks (CBs) |
---|---|---|
lnQ (1) | lnQ (2) | |
D.%BBOD | 0.121 (0.202) | 0.382*** (0.000) |
D.%BSSB | − 0.741*** (0.007) | |
D.LogBSIZE | 0.045 (0.386) | 0.103 (0.176) |
D.INDEP | − 0.026 (0.752) | − 0.220* (0.085) |
D.LogTA | 0.036 (0.568) | 0.228** (0.014) |
D.CAPEX/ASSETS | 0.003** (0.046) | − 0.001 (0.802) |
D.CASH/ASSETS | 0.057 (0.786) | − 0.588* (0.098) |
D.LEV | 0.018*** (0.009) | − 0.012 (0.165) |
BIG4 | − 0.047** (0.027) | − 0.081 (0.377) |
D.HHI | 0.018 (0.808) | 0.397* (0.088) |
D.GDPCAPITA | − 0.001 (0.434) | − 0.001** (0.045) |
D.COUNTRY_GOV | 0.023 (0.365) | 0.137*** (0.001) |
Constant | − 0.064** (0.028) | 0.016 (0.618) |
Year fixed effect | YES | YES |
Observations | 123 | 193 |
Adjusted R2 | 0.008 | 0.267 |
Chi2 LM statistics (p value) Sargan test (p value) | 42*** 0.000 0.243 | 55*** 0.000 0.063 |
%BBOD = %BSSB (F-test) | 0.000 |