Old Second Bancorp, Inc.
DE ˙ DB ˙ US6802771005
17,80 € ↓ -0,30 (-1,66%)
2026-06-02
DEL PRIS
SecurityDE:OSB / Old Second Bancorp, Inc.
InstitutionBoston Partners
Latest Disclosed Ownership1,443,889 shares
Latest Disclosed Value $ 29,278,530
Boston Partners reports 76.66% increase in ownership of OSB / Old Second Bancorp, Inc.

On May 11, 2026 - Boston Partners filed a 13F-HR form disclosing ownership of 1,443,889 shares of Old Second Bancorp, Inc. (DE:OSB) valued at $24,690,502 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 13, 2026 disclosing 817,311 shares of Old Second Bancorp, Inc.. This represents a change in shares of 76.66% during the quarter. The current value of the position is $25,701,224 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)
2026-05-11 2026-03-31 13F OLD SECOND BANCORP INC DEL COM 680277100 1,443,889 626,578 76.66 29,279 83.07 0.0131
2026-02-13 2025-12-31 13F OLD SECOND BANCORP INC ILL COM 680277100 817,311 817,311 15,994 0.0166
2024-08-14 2024-06-30 13F OLD SECOND BANCORP INC ILL COM 680277100 0 -55,735 -100.00 0 -100.00
2024-05-28 2024-03-31 13F/A-1 OLD SECOND BANCORP INC ILL COM 680277100 55,735 41,821 300.57 771 260.28 0.0009
2024-05-13 2024-03-31 13F OLD SECOND BANCORP INC ILL COM 680277100 55,735 41,821 771 0.0004
2024-02-07 2023-12-31 13F OLD SECOND BANCORP INC ILL COM 680277100 13,914 -21,512 -60.72 215 -55.60 0.0003
2023-11-08 2023-09-30 13F OLD SECOND BANCORP INC ILL COM 680277100 35,426 -45,797 -56.38 482 -54.53 0.0007
2023-08-10 2023-06-30 13F OLD SECOND BANCORP INC ILL COM 680277100 81,223 0 0.00 1,061 -7.18 0.0014
2023-05-09 2023-03-31 13F OLD SECOND BANCORP INC ILL COM 680277100 81,223 -167 -0.21 1,142 -12.49 0.0016
2023-02-08 2022-12-31 13F OLD SECOND BANCORP INC ILL COM 680277100 81,390 167 0.21 1,306 23.11 0.0018
2022-11-09 2022-09-30 13F OLD SECOND BANCORP INC ILL COM 680277100 81,223 -73 -0.09 1,060 -2.66 0.0016
2022-08-10 2022-06-30 13F OLD SECOND BANCORP INC ILL COM 680277100 81,296 -7,583 -8.53 1,089 -15.58 0.0015
2022-05-10 2022-03-31 13F OLD SECOND BANCORP INC ILL COM 680277100 88,879 0 0.00 1,290 15.28 0.0016
2022-02-04 2021-12-31 13F OLD SECOND BANCORP INC ILL COM 680277100 88,879 14,299 19.17 1,119 14.89 0.0013
2021-11-05 2021-09-30 13F OLD SECOND BANCORP INC ILL COM 680277100 74,580 -11,726 -13.59 974 -8.97 0.0012
2021-08-12 2021-06-30 13F OLD SECOND BANCORP INC ILL COM 680277100 86,306 -68,087 -44.10 1,070 -47.55 0.0014
2021-05-10 2021-03-31 13F OLD SECOND BANCORP INC ILL COM 680277100 154,393 0 0.00 2,040 30.85 0.0027
2021-02-10 2020-12-31 13F/A-1 OLD SECOND BANCORP INC ILL COM 680277100 154,393 9,575 6.61 1,559 43.69 0.0024
2021-02-04 2020-12-31 13F OLD SECOND BANCORP INC ILL COM 680277100 154,393 9,575 1,559 935.3073
2020-11-13 2020-09-30 13F/A-1 OLD SECOND BANCORP INC ILL COM 680277100 144,818 10,316 7.67 1,085 3.73 0.0020
2020-11-09 2020-09-30 13F OLD SECOND BANCORP INC ILL COM 680277100 134,502 0 1,046 767.8886
2020-08-12 2020-06-30 13F OLD SECOND BANCORP INC ILL COM 680277100 134,502 0 0.00 1,046 12.59 0.0019
2020-05-13 2020-03-31 13F OLD SECOND BANCORP INC ILL COM 680277100 134,502 -67,780 -33.51 929 -65.91 0.0018
2020-02-06 2019-12-31 13F/A-1 OLD SECOND BANCORP INC ILL COM 680277100 202,282 -906 -0.45 2,725 9.75 0.0036
2020-02-05 2019-12-31 13F OLD SECOND BANCORP INC ILL COM 680277100 202,282 -906 2,725 1,532.0746
2019-11-20 2019-09-30 13F/A-1 OLD SECOND BANCORP INC ILL COM 680277100 203,188 -44,322 -17.91 2,483 -21.45 0.0034
2019-11-08 2019-09-30 13F OLD SECOND BANCORP INC ILL COM 680277100 247,510 0 3,161 0.0042
2019-08-26 2019-06-30 13F/A-1 OLD SECOND BANCORP INC ILL COM 680277100 247,510 0 0.00 3,161 1.44 0.0041
2019-08-09 2019-06-30 13F OLD SECOND BANCORP INC ILL COM 680277100 247,510 0 3,161
2019-05-13 2019-03-31 13F/A-1 OLD SECOND BANCORP INC ILL COM 680277100 247,510 -211,000 -46.02 3,116 -47.73 0.0041
2019-05-03 2019-03-31 13F OLD SECOND BANCORP INC ILL COM 680277100 247,510 -211,000 3,116
2019-02-07 2018-12-31 13F OLD SECOND BANCORP INC ILL COM 680277100 458,510 -96,290 -17.36 5,961 -30.46 0.0086
2018-11-14 2018-09-30 13F OLD SECOND BANCORP INC ILL COM 680277100 554,800 -29,000 -4.97 8,572 1.96 0.0100
2018-08-03 2018-06-30 13F OLD SECOND BANCORP INC ILL COM 680277100 583,800 9,000 1.57 8,407 5.22 0.0101
2018-05-04 2018-03-31 13F OLD SECOND BANCORP INC ILL COM 680277100 574,800 11,200 1.99 7,990 3.86 0.0096
2018-02-14 2017-12-31 13F/A-1 OLD SECOND BANCORP INC ILL COM 680277100 563,600 0 0.00 7,693 1.49 0.0091
2018-02-01 2017-12-31 13F OLD SECOND BANCORP INC ILL COM 680277100 563,600 0 7,693
2017-11-02 2017-09-30 13F OLD SECOND BANCORP INC ILL COM 680277100 563,600 194,800 52.82 7,580 77.93 0.0094
2017-08-02 2017-06-30 13F OLD SECOND BANCORP INC ILL COM 680277100 368,800 32,500 9.66 4,260 12.61 0.0054
2017-05-03 2017-03-31 13F OLD SECOND BANCORP INC ILL COM 680277100 336,300 300 0.09 3,783 1.89 0.0048
2017-02-06 2016-12-31 13F OLD SECOND BANCORP INC ILL COM 680277100 336,000 -124,760 -27.08 3,713 -3.03 0.0049
2016-11-09 2016-09-30 13F OLD SECOND BANCORP INC ILL COM 680277100 460,760 23,290 5.32 3,829 28.15 0.0054
2016-08-05 2016-06-30 13F OLD SECOND BANCORP INC ILL COM 680277100 437,470 8,510 1.98 2,988 -2.86 0.0043
2016-05-12 2016-03-31 13F OLD SECOND BANCORP INC ILL COM 680277100 428,960 -50,810 -10.59 3,076 -18.21 0.0045
2016-02-08 2015-12-31 13F OLD SECOND BANCORP INC ILL COM 680277100 479,770 -37,960 -7.33 3,761 16.62 0.0054
2015-11-10 2015-09-30 13F OLD SECOND BANCORP INC ILL COM 680277100 517,730 -42,510 -7.59 3,225 -12.79 0.0049
2015-08-10 2015-06-30 13F OLD SECOND BANCORP INC ILL COM 680277100 560,240 -920 -0.16 3,698 15.20 0.0053
2015-05-05 2015-03-31 13F OLD SECOND BANCORP INC ILL COM 680277100 561,160 109,135 24.14 3,210 32.26 0.0048
2015-02-09 2014-12-31 13F OLD SECOND BANCORP INC ILL COM 680277100 452,025 85,825 23.44 2,427 37.82 0.0036
2014-11-12 2014-09-30 13F OLD SECOND BANCORP INC ILL COM 680277100 366,200 800 0.22 1,761 -3.03 0.0029
2014-08-08 2014-06-30 13F OLD SECOND BANCORP INC ILL COM 680277100 365,400 365,400 1,816 0.0030
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.