BankingStats

Old Second National Bank

Aurora, Illinois, Kane County

$6.9B in total assets, the 231st largest of 4,309 US banks and 10th of 328 headquartered in Illinois.

FDIC certificate
3603
Established
1887
Owned by
Old Second Bcorp Inc
Primary regulator
OCC
Website
www.oldsecond.com

At a glance

Compared with 50 banks headquartered in Illinois with $1 billion to $10 billion in assets, as of June 30, 2026.

Measure This bank Percentile Peer range, middle 90% Peer median
Total assets $6.9B 90% $2.7B
Loans $5.2B 92% $2.0B
Deposits $5.5B 84% $2.3B
Return on assets 1.54% 69% 1.39%
Net interest margin 5.26% 98% 3.53%
Efficiency ratio 49.5% 37% 51.3%
Equity to assets 13.48% 96% 9.97%
Loans to deposits 96% 86% 86%

Growth

Total assets grew 16.1% a year over the last 5 years and 12.4% a year over 10 years, including 3 acquisitions in the last 10 years.

Acquisitions

ClosedAcquired bankAssets at acquisition
Jul 2025Evergreen Bank Group Oak Brook, IL$1.4B
Dec 2021West Suburban Bank Lombard, IL$2.9B
Apr 2018ABC Bank Chicago, IL$334M
Feb 2008Heritage Bank Frankfort, IL$344M
Jul 2007Old Second Bank-Yorkville Yorkville, IL, an affiliate under the same holding company$390M
Jul 2007Old Second Bank-Kane County Elburn, IL, an affiliate under the same holding company$419M
Feb 2000Bank of Sugar Grove Sugar Grove, IL, an affiliate under the same holding company$45M
Jan 1999The Old Second Community Bank of North Aurora North Aurora, IL, an affiliate under the same holding company$59M
Jan 1999The Old Second Community Bank of Aurora Aurora, IL, an affiliate under the same holding company$48M
Jun 1997First State Bank of Maple Park Maple Park, IL$61M

Where they operate

57 branches in 7 counties.

Largest markets by deposits

CountyDepositsMarket shareRank
Kane County, IL$1.9B12.4%3 of 31
Dupage County, IL$1.8B3.3%10 of 43
Cook County, IL$1.0B0.2%33 of 90
Kendall County, IL$401M14.2%4 of 13
Will County, IL$250M1.1%13 of 34
Lasalle County, IL$52M1.3%15 of 22

Deposits by branch from the FDIC Summary of Deposits, June 2026. Rank among all banks with branches in that county.

Branch history since 2016

Net gain of 33 branches since 2016 (24 to 57, +137.5%). 9 opened, 34 acquired, 10 closed or sold.

PeriodWhat happenedOpened or acquiredClosed or soldNet changeBranches at end
Start of 2016Starting point24
2016Opened Chicago10+125
2017Closed Maple Park01−124
2018Acquired ABC Bank40+428
2019Opened Joliet10+129
2021Acquired West Suburban BankOpened Lombard290+2958
2022Closed 7 in Illinois07−751
2023Opened Downers GroveClosed Kaneville11051
2025Acquired Evergreen Bank GroupOpened 5 in Illinois, closed Darien71+657

Balance sheet and earnings

Loans by type

TypeShareThis bankPeers
Commercial real estate 35%28%
Business (C&I) 22%26%
Consumer 17%5%
1-4 family residential 10%14%
Multifamily 7%9%
Construction and land 3%7%
Farmland 0%3%
Agricultural 0%2%
Other 6%5%

Deposits by type

TypeShareThis bankPeers
Other interest-bearing 51%55%
Noninterest-bearing 32%20%
Time deposits 17%24%

Brokered deposits are 0.6% of deposits (peers 8.0%).

Return on assets

Trailing four quarters, with the peer median.

Credit and capital

This bankPeer median
Noncurrent loans1.08%0.49%
Net charge-offs, annualized0.73%0.07%
Reserves to loans1.34%1.07%
Leverage ratio12.05%10.08%

Noncurrent loans exclude government-guaranteed portions.

Similar size in Illinois

Largest competitors in Kane County, IL

Figures as of June 30, 2026 from the bank's Call Report, FDIC structure and branch data, and the Federal Reserve. Short link: bankingstats.com/old-second