Old Second Bancorp, Inc.
DE ˙ DB ˙ US6802771005
18,20 € ↑0,60 (3,41%)
2026-06-05
DEL PRIS
SecurityDE:OSB / Old Second Bancorp, Inc.
InstitutionBlair William & Co/il
Latest Disclosed Ownership162,883 shares
Latest Disclosed Value $ 3,283,729
Blair William & Co/il reports 5.62% increase in ownership of OSB / Old Second Bancorp, Inc.

On May 8, 2026 - Blair William & Co/il filed a 13F-HR form disclosing ownership of 162,883 shares of Old Second Bancorp, Inc. (DE:OSB) valued at $2,785,299 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 154,219 shares of Old Second Bancorp, Inc.. This represents a change in shares of 5.62% during the quarter. The current value of the position is $2,964,471 USD.

Institutional Ownership: 13F and NPORT Filings

The Security and Class in the table below are shown exactly as filed by the investor. We do our best to track continuity of investments through acquisitions, and this will be reflected in the table as changes in names. In addition to descriptive data, performance of the investment is shown over time. To calculate quarterly performance, we first calculate cost basis of the shares purchased during the quarter, then use that to calculate gross profit. Quarterly return is Gross Profit / Starting Portfolio value.

Note that cost basis is calculated and stored in thousands, so small quarterly changes in shares frequently result in a cost basis of zero.

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Disclosed Equity Positions (from 13F/NPORT Filings)
File
Date		 Effective
Date		Form Security Class ID Avg Price
Paid (Est)		 Reported
Shares		 ΔShares ΔShares
(%)		 Reported
Value
(x1000)		 ΔValue
(%)		 Alloc
(%)		 ΔAlloc ΔAlloc (%) Cost Basis
(x1000)		 Unrealized
Gain/Loss
(x1000)
2026-05-08 2026-03-31 13F OLD SECOND BANCORP INC DEL COM 680277100 162,883 8,664 5.62 3,284 9.18 0.0094
2026-02-17 2025-12-31 13F OLD SECOND BANCORP INC ILL COM 680277100 154,219 -217 -0.14 3,007 12.66 0.0081
2025-11-12 2025-09-30 13F OLD SECOND BANCORP INC ILL COM 680277100 154,436 136,416 757.03 2,669 736.68 0.0071
2025-07-24 2025-06-30 13F OLD SECOND BANCORP INC ILL COM 680277100 18,020 21 0.12 320 6.69 0.0009
2025-05-09 2025-03-31 13F OLD SECOND BANCORP INC ILL COM 680277100 17,999 17 0.09 300 -6.27 0.0009
2025-02-12 2024-12-31 13F OLD SECOND BANCORP INC ILL COM 680277100 17,982 -644 -3.46 320 10.00 0.0009
2024-11-12 2024-09-30 13F OLD SECOND BANCORP INC ILL COM 680277100 18,626 16 0.09 290 5.45 0.0009
2024-08-12 2024-06-30 13F OLD SECOND BANCORP INC ILL COM 680277100 18,610 7,525 67.88 276 79.74 0.0009
2024-05-09 2024-03-31 13F OLD SECOND BANCORP INC ILL COM 680277100 11,085 3 0.03 153 -10.53 0.0005
2024-02-12 2023-12-31 13F OLD SECOND BANCORP INC ILL COM 680277100 11,082 2 0.02 171 14.00 0.0006
2023-11-09 2023-09-30 13F OLD SECOND BANCORP INC ILL COM 680277100 11,080 2 0.02 151 4.17 0.0006
2023-08-11 2023-06-30 13F OLD SECOND BANCORP INC ILL COM 680277100 11,078 3 0.03 145 -7.10 0.0005
2023-05-12 2023-03-31 13F OLD SECOND BANCORP INC ILL COM 680277100 11,075 2 0.02 156 -12.43 0.0006
2023-02-10 2022-12-31 13F OLD SECOND BANCORP INC ILL COM 680277100 11,073 2 0.02 178 22.92 0.0008
2022-11-09 2022-09-30 13F OLD SECOND BANCORP INC ILL COM 680277100 11,071 3 0.03 144 -2.70 0.0007
2022-08-10 2022-06-30 13F OLD SECOND BANCORP INC ILL COM 680277100 11,068 2 0.02 148 -8.07 0.0007
2022-05-13 2022-03-31 13F OLD SECOND BANCORP INC ILL COM 680277100 11,066 2 0.02 161 15.83 0.0006
2022-02-14 2021-12-31 13F OLD SECOND BANCORP INC ILL COM 680277100 11,064 3 0.03 139 -3.47 0.0004
2021-11-12 2021-09-30 13F OLD SECOND BANCORP INC ILL COM 680277100 11,061 3 0.03 144 5.11 0.0005
2021-08-12 2021-06-30 13F OLD SECOND BANCORP INC ILL COM 680277100 11,058 2 0.02 137 -6.16 0.0005
2021-05-13 2021-03-31 13F OLD SECOND BANCORP INC ILL COM 680277100 11,056 -25,499 -69.76 146 -60.43 0.0006
2021-02-09 2020-12-31 13F OLD SECOND BANCORP INC ILL COM 680277100 36,555 -28,194 -43.54 369 -23.92 0.0014
2020-11-06 2020-09-30 13F OLD SECOND BANCORP INC ILL COM 680277100 64,749 10,739 19.88 485 15.48 0.0021
2020-08-12 2020-06-30 13F OLD SECOND BANCORP INC ILL COM 680277100 54,010 -61,404 -53.20 420 -47.37 0.0020
2020-05-11 2020-03-31 13F OLD SECOND BANCORP INC ILL COM 680277100 115,414 -13,545 -10.50 798 -54.06 0.0050
2020-02-13 2019-12-31 13F OLD SECOND BANCORP INC ILL COM 680277100 128,959 -14,829 -10.31 1,737 -1.14 0.0089
2019-11-12 2019-09-30 13F OLD SECOND BANCORP INC ILL COM 680277100 143,788 -1,921 -1.32 1,757 -5.59 0.0101
2019-08-13 2019-06-30 13F OLD SECOND BANCORP INC ILL COM 680277100 145,709 -274 -0.19 1,861 1.25 0.0106
2019-05-14 2019-03-31 13F OLD SECOND BANCORP INC ILL COM 680277100 145,983 1,473 1.02 1,838 -2.18 0.0112
2019-02-14 2018-12-31 13F OLD SECOND BANCORP INC ILL COM 680277100 144,510 30,619 26.88 1,879 6.76 0.0137
2018-11-13 2018-09-30 13F OLD SECOND BANCORP INC ILL COM 680277100 113,891 20,237 21.61 1,760 30.47 0.0108
2018-08-13 2018-06-30 13F OLD SECOND BANCORP INC ILL COM 680277100 93,654 52,406 127.05 1,349 135.43 0.0092
2018-05-15 2018-03-31 13F OLD SECOND BANCORP INC ILL COM 680277100 41,248 41,248 573 0.0041
2017-08-04 2017-06-30 13F OLD SECOND BANCORP COM 680277100 0 -60,916 -100.00 0 -100.00
2017-05-10 2017-03-31 13F OLD SECOND BANCORP COM 680277100 60,916 0 0.00 684 1.63 0.0055
2017-02-14 2016-12-31 13F OLD SECOND BANCORP COM 680277100 60,916 40,290 195.34 673 293.57 0.0060
2016-11-14 2016-09-30 13F OLD SECOND BANCORP INC-DEL ADR 680277100 20,626 20,626 171 0.0015
Legend
Shares
The total number of shares held by the institution at the end of the reporting period (the effective date). This is provided in the filing.
Value
The total value of the shares as of the effective date. This is provided in the filing.
Avg. Share Price
The weighted average share price of the shares held by the institution. We use FIFO accounting to determine this price
Class
This is the security class as indicated by the filer. There are a variety of values for this field. Common values include "EC" = equity common, "EP" - equity preferred
Allocation (%)
The percent of the institution's portfolio that this position represents. This is provided in NPORT filings. For 13F filings, we calculate it.
Change in Allocation
The change in allocation from the prior reporting period. This is calculated as current allocation - prior allocation.
Change in Allocation (%)
The percent change in allocation from the prior reporting period. This is calculated as (current allocation - prior allocation) / prior allocation.
Cost Basis
The total cost of the shares held. This is calculated as reported shares * avg. share price
Unrealized Gain/Loss
This is the market value of the position as of the effective date minus the cost basis.