Branch Network
Old Second National Bank Locations & Branches Aurora, Illinois
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Old Second National Bank operates 57 branches from its headquarters in Aurora, IL, .
Old Second National Bank branch network
All 57 branches are in ILLINOIS, across 41 cities. Lombard, IL has the most of its branches, 6. Its largest office by deposits is its main office in Aurora, IL, with $866.7M (15.9% of its branch deposits). On June 30, 2025 it had 56 branches, 1 fewer than in 2026.
Old Second National Bank at a glance
Its CET1 capital ratio was 13.72% at Q2 2026, comfortably above the 7% level required once the capital conservation buffer is included.
- Total assets, Q2 2026
- $6.86B
- CET1 ratio, Q2 2026
- 13.72%
- Deposit insurance
- FDIC
- Regulator
- OCC
- Latest call report
- Q2 2026, FFIEC 041
- Established
- 1887
Full financial profile · Is Old Second National Bank safe? · Old Second National Bank call report · Routing number
Deposit market share
Share of all FDIC-insured deposits held in each area, from the June 30, 2026 Summary of Deposits. Rank 1 is the largest holder. Shares are by bank charter, not by holding company.
| Area | Rank | Deposit share | Deposits |
|---|---|---|---|
| City: Aurora, IL (5 branches) | 1 of 15 | 29.3% | $1.24B |
| State: IL (57 branches) | 20 of 379 | 0.7% | $5.47B |
Ranked by total assets among banks headquartered in the state: Largest banks in Illinois.
Share by county and metro area
Old Second National Bank's share of FDIC-insured deposits in the counties and metro areas where it has branches, from the June 30, 2026 Summary of Deposits. Up to the ten largest of each are shown, by the bank's deposits. Rank 1 is the largest holder. Banks only: credit unions are not in the Summary of Deposits.
Counties
| County | Rank | Deposit share | Deposits | County total |
|---|---|---|---|---|
| Kane, IL (14 branches) | 3 of 31 | 12.4% | $1.92B | $15.47B |
| Dupage, IL (22 branches) | 10 of 43 | 3.3% | $1.80B | $54.96B |
| Cook, IL (10 branches) | 33 of 89 | 0.2% | $1.00B | $463.76B |
| Kendall, IL (4 branches) | 4 of 13 | 14.2% | $400.8M | $2.81B |
| Will, IL (5 branches) | 13 of 34 | 1.1% | $250.5M | $23.33B |
| Lasalle, IL (1 branch) | 15 of 22 | 1.3% | $51.5M | $4.10B |
| Dekalb, IL (1 branch) | 9 of 9 | 1.4% | $40.2M | $2.98B |
Metro areas
| Metro area | Rank | Deposit share | Deposits | Metro total |
|---|---|---|---|---|
| Chicago-Naperville-Elgin, IL-IN-WI (56 branches) | 18 of 150 | 0.9% | $5.42B | $632.03B |
| Ottawa, IL (1 branch) | 22 of 26 | 0.9% | $51.5M | $5.55B |
| Branch | Location | ZIP | Deposits |
|---|---|---|---|
| Old Second National Bank (main office) | Aurora, IL | 60506 | $866.7M |
| Downtown Chicago Branch | Chicago, IL | 60606 | $440.4M |
| Westmore Branch | Lombard, IL | 60148 | $299.5M |
| Cass Avenue Branch | Darien, IL | 60561 | $246.8M |
| Oak Brook Branch | Oak Brook, IL | 60523 | $240.7M |
| Evergreen Park Branch | Evergreen Park, IL | 60805 | $179.7M |
| Countryside Branch | Yorkville, IL | 60560 | $167.8M |
| Oswego Branch | Oswego, IL | 60543 | $157.6M |
| Elburn Branch | Elburn, IL | 60119 | $142.3M |
| West Galena Branch | Aurora, IL | 60506 | $122.8M |
| Gary Avenue Branch | Carol Stream, IL | 60188 | $111.3M |
| Stratford Square Branch | Bloomingdale, IL | 60108 | $109.3M |
| Old Second Batavia Branch | Batavia, IL | 60510 | $107.4M |
| Farnsworth Branch | Aurora, IL | 60505 | $106.4M |
| North Aurora Branch | North Aurora, IL | 60542 | $98.7M |
| Chicago Heights Branch | Chicago Heights, IL | 60411 | $95.1M |
| Burlington Branch | Burlington, IL | 60109 | $94.1M |
| Frankfort Branch | Frankfort, IL | 60423 | $92.8M |
| Sugar Grove Branch | Sugar Grove, IL | 60554 | $88.2M |
| Finley Road Branch | Downers Grove, IL | 60515 | $87.6M |
| South Main Branch | Lombard, IL | 60148 | $81.4M |
| Glendale Heights Branch | Glendale Heights, IL | 60139 | $80.4M |
| Charlestowne Branch | St Charles, IL | 60174 | $78.2M |
| Eola Road Branch | Aurora, IL | 60504 | $74.1M |
| Bartlett Branch | Bartlett, IL | 60103 | $73.0M |
| Naperville Branch | Naperville, IL | 60540 | $71.9M |
| Orchard Branch | Aurora, IL | 60506 | $68.1M |
| Palos Heights Branch | Palos Heights, IL | 60463 | $61.0M |
| Danada Branch | Wheaton, IL | 60189 | $60.9M |
| Bolingbrook West Branch | Bolingbrook, IL | 60440 | $58.3M |
| North Main Branch | Lombard, IL | 60148 | $58.1M |
| Bensenville Branch | Bensenville, IL | 60106 | $56.3M |
| South Holland Branch | South Holland, IL | 60473 | $54.9M |
| Wasco Branch | Wasco, IL | 60183 | $54.4M |
| 6400 West North Ave Br | Chicago, IL | 60707 | $54.1M |
| Ottawa Branch | Ottawa, IL | 61350 | $51.5M |
| Flossmoor Branch | Flossmoor, IL | 60422 | $49.6M |
| Plano West Branch | Plano, IL | 60545 | $46.4M |
| Fair Oaks Branch | Carol Stream, IL | 60188 | $43.9M |
| Villa Park Branch | Villa Park, IL | 60181 | $42.7M |
| Sycamore Branch | Sycamore, IL | 60178 | $40.2M |
| Warrenville Branch | Warrenville, IL | 60555 | $39.3M |
| Romeoville Branch | Romeoville, IL | 60446 | $37.5M |
| Bolingbrook East Branch | Bolingbrook, IL | 60440 | $37.3M |
| South Elgin Branch | South Elgin, IL | 60177 | $34.9M |
| St. Charles Branch | St. Charles, IL | 60174 | $33.1M |
| 9443 South Ashland Avenue Branch | Chicago, IL | 60620 | $31.3M |
| Montgomery Branch | Montgaomery, IL | 60538 | $29.0M |
| Elgin-Route 20 Branch | Elgin, IL | 60123 | $27.1M |
| Joliet Branch | Joliet, IL | 60435 | $24.7M |
| Hegewisch Branch | Chicago, IL | 60633 | $24.0M |
| Oak Brook Terrace Branch | Oak Brook Terrace, IL | 60181 | $22.3M |
| Taylor Street Branch | Chicago, IL | 60607 | $12.1M |
| Metra Main Wsb Xpress Branch | Lombard, IL | 60148 | $0 |
| Wsb Visa Building Limited Service Branch | Lombard, IL | 60148 | $0 |
| Downers Grove Highland Branch | Downers Grove, IL | 60515 | $0 |
| Financial Center | Lombard, IL | 60148 | $0 |
Source: FDIC Summary of Deposits, June 30, 2026. How the survey works.
Regulator records: FDIC BankFind (cert 3603) · FFIEC NIC profile (RSSD 936136)