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Regulatory & Capital Matters (Details) | Dec. 31, 2018 | Dec. 31, 2017
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Regulatory & Capital Matters |  |
Tier 1 capital leverage ratio (as a percent) | 10.08% | 10.08%
Risk-based capital ratio (as a percent) | 12.63% | 12.93%
Old Second National Bank |  |
Regulatory & Capital Matters |  |
Tier 1 capital leverage ratio (as a percent) | 11.36% | 10.79%
Risk-based capital ratio (as a percent) | 14.14% | 13.78%
Minimum | Old Second National Bank |  |
Regulatory & Capital Matters |  |
Tier 1 capital leverage ratio (as a percent) | 8.00% |
Risk-based capital ratio (as a percent) | 12.00% |

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