Institutional HoldersBeta

Who holds a company, from every 13F filed for the quarter, one row per filer exactly as filed, against the latest share count the company reported.

OLD SECOND BANCORP INC

CIK 0000357173OSBC· quarter ending 2026-06-30

Shares outstanding

50,875,716

as of 2026-08-04 · 10-Q cover page, filed 2026-08-06

Held by 13F filers

38,829,690

76.3% of shares outstanding

Holders

184

-4 vs 2026-03-31 · 19 new, 23 exited

Value

$903.3M

shares +2.8% vs prior quarter

Share classes (cover page of the 10-Q filed 2026-08-06, as of 2026-08-04)

Class	Listed	Shares outstanding	Held by 13F filers	% of class	Holders	CUSIP
Common stock	OSBC · NASDAQ	50,875,716	38,829,690	76.3%	184	680277100

Each class is compared with its own share count; classes are not added together. A class that is not exchange-listed cannot be held by 13F filers.

Securities (CUSIPs held in 13F this quarter)

tick to combine

Count	CUSIP	Class (as filers write it)	Holders	Shares held	Class shares	% of class	Value	Options	Mapped via
	680277100	COM	184	38,829,690	50,875,716	76.3%	$903.3M	—	13DG	holders →

Totals combine the ticked CUSIPs and update as you tick: common-stock classes by default; preferreds, notes, warrants and depositary shares are listed but not counted. "holders →" shows a single CUSIP on its own. Bonds are held as a principal amount, not shares. Options positions are never counted as holdings.

Top holders (184 of 184 · 680277100)

change vs 2026-03-31

#	Filer	Shares	% of class	Value	Change
1	BlackRock, Inc.	4,298,683	8.45%	$100.2M	+172,439 (+4.2%)
2	DIMENSIONAL FUND ADVISORS LP	2,498,671	4.91%	$58.3M	+109,809 (+4.6%)
3	VANGUARD CAPITAL MANAGEMENT LLC	2,179,877	4.28%	$50.8M	-71,972 (-3.2%)
4	STATE STREET CORP	1,839,202	3.62%	$42.9M	+239,900 (+15.0%)
5	Davis Asset Management, L.P.	1,800,000	3.54%	$42.0M	—
6	AMERICAN CENTURY COMPANIES INC	1,783,820	3.51%	$41.6M	+192,877 (+12.1%)
7	GOLDMAN SACHS GROUP INC	1,624,852	3.19%	$37.9M	-66,671 (-3.9%)
8	FJ Capital Management LLC	1,460,413	2.87%	$34.1M	-44,689 (-3.0%)
9	Boston Partners	1,415,165	2.78%	$32.9M	-28,724 (-2.0%)
10	GEODE CAPITAL MANAGEMENT, LLC	1,349,432	2.65%	$31.5M	+67,421 (+5.3%)
11	KENNEDY CAPITAL MANAGEMENT LLC	1,236,983	2.43%	$28.8M	-31,507 (-2.5%)
12	BANC FUNDS CO LLC	1,034,143	2.03%	$24.1M	+5,000 (+0.5%)
13	MANUFACTURERS LIFE INSURANCE COMPANY, THE	872,651	1.72%	$20.4M	-6,019 (-0.7%)
14	VANGUARD PORTFOLIO MANAGEMENT LLC	819,368	1.61%	$19.1M	+106,935 (+15.0%)
15	Stieven Capital Advisors, L.P.	815,328	1.60%	$19.0M	+41,800 (+5.4%)
16	River Street Advisors LLC	779,008	1.53%	$18.2M	+32,348 (+4.3%)
17	ALLIANCEBERNSTEIN L.P.	641,845	1.26%	$12.9M	-49,000 (-7.1%)
18	JPMORGAN CHASE & CO	555,602	1.09%	$12.9M	-145,351 (-20.7%)
19	NORTHERN TRUST CORP	555,408	1.09%	$13.0M	-208,933 (-27.3%)
20	WELLINGTON MANAGEMENT GROUP LLP	544,345	1.07%	$12.7M	-313,440 (-36.5%)
21	Nuveen, LLC	492,162	0.97%	$11.5M	+72,520 (+17.3%)
22	BRIDGEWAY CAPITAL MANAGEMENT, LLC	453,323	0.89%	$10.6M	+15,068 (+3.4%)
23	CHARLES SCHWAB INVESTMENT MANAGEMENT INC	431,304	0.85%	$10.1M	+394 (+0.1%)
24	AQR CAPITAL MANAGEMENT LLC	386,234	0.76%	$9.0M	-5,726 (-1.5%)
25	BANK OF AMERICA CORP /DE/	372,648	0.73%	$8.7M	+41,318 (+12.5%)
26	Gator Capital Management, LLC	359,730	0.71%	$8.4M	+8,250 (+2.3%)
27	Bank of New York Mellon Corp	342,013	0.67%	$8.0M	+4,749 (+1.4%)
28	VANGUARD FIDUCIARY TRUST CO	341,200	0.67%	$8.0M	+5,717 (+1.7%)
29	CONGRESS ASSET MANAGEMENT CO	338,650	0.67%	$7.9M	NEW
30	MORGAN STANLEY	318,318	0.63%	$7.4M	+39,931 (+14.3%)
31	CITADEL ADVISORS LLC	304,021	0.60%	$7.1M	+243,956 (+406.2%)
32	FRANKLIN RESOURCES INC	259,324	0.51%	$6.0M	+171,158 (+194.1%)
33	Empowered Funds, LLC	248,627	0.49%	$5.8M	+15,068 (+6.5%)
34	Thrivent Financial for Lutherans	242,278	0.48%	$5.7M	+99,159 (+69.3%)
35	Mariner, LLC	225,303	0.44%	$5.3M	+207,236 (+1147.0%)
36	ARROWSTREET CAPITAL, LIMITED PARTNERSHIP	210,745	0.41%	$4.9M	+69,719 (+49.4%)
37	Forum Financial Management, LP	205,673	0.40%	$4.8M	+12 (+0.0%)
38	GREAT LAKES ADVISORS, LLC	203,909	0.40%	$4.8M	+5,905 (+3.0%)
39	TWO SIGMA INVESTMENTS, LP	200,819	0.39%	$4.7M	+133,462 (+198.1%)
40	Squarepoint Ops LLC	167,884	0.33%	$3.9M	-2,767 (-1.6%)
41	BLAIR WILLIAM & CO/IL	163,228	0.32%	$3.8M	+345 (+0.2%)
42	Siena Capital Partners GP, LLC	163,038	0.32%	$3.8M	—
43	EJF Capital LP	151,358	0.30%	$3.5M	+188 (+0.1%)
44	UBS Group AG	147,223	0.29%	$3.4M	-112,051 (-43.2%)
45	VICTORY CAPITAL MANAGEMENT INC	141,914	0.28%	$3.3M	+2,860 (+2.1%)
46	Russell Investments Group, Ltd.	135,010	0.27%	$3.1M	+23,061 (+20.6%)
47	Elizabeth Park Capital Advisors, Ltd.	129,457	0.25%	$3.0M	-37,000 (-22.2%)
48	SEI INVESTMENTS CO	117,666	0.23%	$2.7M	-85,422 (-42.1%)
49	D. E. Shaw & Co., Inc.	114,326	0.22%	$2.7M	NEW
50	Curi Capital, LLC	100,505	0.20%	$2.3M	—
51	Swiss National Bank	100,400	0.20%	$2.3M	+1,700 (+1.7%)
52	MENDON CAPITAL ADVISORS CORP	100,000	0.20%	$2.3M	—
53	Fisher Asset Management, LLC	97,285	0.19%	$2.3M	—
54	FIRST TRUST ADVISORS LP	94,347	0.19%	$2.2M	+75,587 (+402.9%)
55	State of New Jersey Common Pension Fund D	88,964	0.17%	$2.1M	-40,415 (-31.2%)
56	BARCLAYS PLC	87,603	0.17%	$2.0M	+601 (+0.7%)
57	MSH Capital Advisors LLC	84,826	0.17%	$2.0M	—
58	PRINCIPAL FINANCIAL GROUP INC	80,534	0.16%	$1.9M	+5,444 (+7.2%)
59	Invesco Ltd.	77,241	0.15%	$1.8M	-4,371 (-5.4%)
60	UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC	76,132	0.15%	$1.8M	+8,602 (+12.7%)
61	JCSD Capital, LLC	74,100	0.15%	$1.7M	—
62	Quantinno Capital Management LP	73,556	0.14%	$1.7M	+23,677 (+47.5%)
63	RHUMBLINE ADVISERS	69,998	0.14%	$1.6M	+3,903 (+5.9%)
64	HSBC HOLDINGS PLC	66,312	0.13%	$1.5M	-18,871 (-22.2%)
65	BANK OF MONTREAL /CAN/	64,272	0.13%	$1.5M	-54,193 (-45.7%)
66	MARTINGALE ASSET MANAGEMENT L P	61,224	0.12%	$1.4M	-26,000 (-29.8%)
67	Sara-Bay Financial	61,000	0.12%	$1.4M	-33,063 (-35.1%)
68	HUDSON EDGE INVESTMENT PARTNERS INC.	60,706	0.12%	$1.4M	+28,624 (+89.2%)
69	Knights of Columbus Asset Advisors LLC	57,364	0.11%	$1.3M	-74,077 (-56.4%)
70	CITIGROUP INC	55,100	0.11%	$1.3M	+17,869 (+48.0%)
71	Campbell & CO Investment Adviser LLC	54,037	0.11%	$1.3M	+18,593 (+52.5%)
72	Creative Planning	53,848	0.11%	$1.3M	+6,899 (+14.7%)
73	ExodusPoint Capital Management, LP	53,769	0.11%	$1.3M	NEW
74	CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM	51,243	0.10%	$1.2M	+4,447 (+9.5%)
75	DEUTSCHE BANK AG\	51,034	0.10%	$1.2M	+4,557 (+9.8%)
76	SUSQUEHANNA FUNDAMENTAL INVESTMENTS, LLC	50,693	0.10%	$1.2M	+34,268 (+208.6%)
77	IEQ CAPITAL, LLC	50,309	0.10%	$1.2M	-2,198 (-4.2%)
78	PRICE T ROWE ASSOCIATES INC /MD/	46,957	0.09%	$1.1M	+5,494 (+13.3%)
79	WEALTH ENHANCEMENT ADVISORY SERVICES, LLC	45,547	0.09%	$1.0M	+2,763 (+6.5%)
80	HighTower Advisors, LLC	43,563	0.09%	$1.0M	-289 (-0.7%)
81	WELLS FARGO & COMPANY/MN	42,857	0.08%	$999K	+23,035 (+116.2%)
82	Legal & General Group Plc	40,578	0.08%	$946K	+471 (+1.2%)
83	FMR LLC	39,922	0.08%	$931K	+34,080 (+583.4%)
84	VANGUARD ASSET MANAGEMENT, Ltd	38,777	0.08%	$904K	+8,318 (+27.3%)
85	Aquatic Capital Management LLC	37,700	0.07%	$879K	NEW
86	Hunter Perkins Capital Management, LLC	34,889	0.07%	$814K	-11,295 (-24.5%)
87	GSA CAPITAL PARTNERS LLP	34,819	0.07%	$812K	NEW
88	Sanctuary Advisors, LLC	33,909	0.07%	$791K	NEW
89	ROTHSCHILD INVESTMENT LLC	32,819	0.06%	$765K	+4,514 (+15.9%)
90	Rafferty Asset Management, LLC	32,388	0.06%	$755K	-3,307 (-9.3%)
91	Vanguard Global Advisers, LLC	31,893	0.06%	$744K	—
92	STATE OF WISCONSIN INVESTMENT BOARD	30,528	0.06%	$712K	+12,643 (+70.7%)
93	ROYAL BANK OF CANADA	30,051	0.06%	$701K	-1,518 (-4.8%)
94	MetLife Investment Management, LLC	29,641	0.06%	$691K	+1,588 (+5.7%)
95	OSAIC HOLDINGS, INC.	27,233	0.05%	$635K	+17,756 (+187.4%)
96	Jupiter Topco LLC	26,232	0.05%	$612K	NEW
97	ENVESTNET ASSET MANAGEMENT INC	24,612	0.05%	$574K	+5,021 (+25.6%)
98	MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd.	23,389	0.05%	$545K	-252 (-1.1%)
99	Lakewood Asset Management LLC	22,955	0.05%	$535K	+304 (+1.3%)
100	RENAISSANCE TECHNOLOGIES LLC	21,221	0.04%	$495K	-69,004 (-76.5%)
101	MERCER GLOBAL ADVISORS INC /ADV	20,591	0.04%	$480K	+3,852 (+23.0%)
102	Savant Capital, LLC	20,218	0.04%	$440K	+10,130 (+100.4%)
103	NICOLET BANKSHARES INC	20,210	0.04%	$469K	—
104	RAYMOND JAMES FINANCIAL INC	19,309	0.04%	$450K	+26 (+0.1%)
105	NEW YORK STATE COMMON RETIREMENT FUND	18,766	0.04%	$438K	+4,400 (+30.6%)
106	BNP PARIBAS FINANCIAL MARKETS	18,727	0.04%	$437K	+4,977 (+36.2%)
107	4WEALTH ADVISORS, INC.	18,300	0.04%	$425K	-350 (-1.9%)
108	AMERIPRISE FINANCIAL INC	17,570	0.03%	$410K	-5,724 (-24.6%)
109	Centennial Wealth Advisory LLC	17,556	0.03%	$409K	+49 (+0.3%)
110	PUBLIC EMPLOYEES RETIREMENT ASSOCIATION OF COLORADO	17,258	0.03%	$402K	—
111	FEDERATED HERMES, INC.	17,223	0.03%	$402K	-605 (-3.4%)
112	Y-Intercept (Hong Kong) Ltd	16,728	0.03%	$390K	-35,848 (-68.2%)
113	Cetera Investment Advisers	15,802	0.03%	$369K	+4,100 (+35.0%)
114	Kestra Advisory Services, LLC	14,958	0.03%	$349K	+49 (+0.3%)
115	Police & Firemen's Retirement System of New Jersey	14,232	0.03%	$332K	—
116	Zurcher Kantonalbank (Zurich Cantonalbank)	14,193	0.03%	$331K	—
117	SENTINEL TRUST CO LBA	14,051	0.03%	$328K	—
118	ARIZONA STATE RETIREMENT SYSTEM	13,812	0.03%	$322K	+69 (+0.5%)
119	PRINCETON CAPITAL MANAGEMENT LLC	13,770	0.03%	$321K	—
120	Sterling Capital Management LLC	13,405	0.03%	$313K	+11,734 (+702.2%)
121	CAPTRUST FINANCIAL ADVISORS	13,309	0.03%	$310K	-4,811 (-26.6%)
122	STATE BOARD OF ADMINISTRATION OF FLORIDA RETIREMENT SYSTEM	12,390	0.02%	$289K	—
123	Black Maple Capital Management LP	12,000	0.02%	$280K	-27,224 (-69.4%)
124	Arax Advisory Partners	11,778	0.02%	$275K	+10,358 (+729.4%)
125	Virtu Financial LLC	11,758	0.02%	$274K	NEW
126	Stratos Wealth Partners, LTD.	11,663	0.02%	$272K	—
127	CALDWELL SUTTER CAPITAL, INC.	11,000	0.02%	$257K	—
128	HOHIMER WEALTH MANAGEMENT, LLC	10,957	0.02%	$256K	+45 (+0.4%)
129	SG Americas Securities, LLC	10,863	0.02%	$253K	-508 (-4.5%)
130	KLP KAPITALFORVALTNING AS	10,700	0.02%	$250K	—
131	VOYA INVESTMENT MANAGEMENT LLC	10,636	0.02%	$248K	NEW
132	INTECH INVESTMENT MANAGEMENT LLC	10,560	0.02%	$246K	-1,422 (-11.9%)
133	J.W. COLE ADVISORS, INC.	10,509	0.02%	$245K	NEW
134	Cerity Partners LLC	10,472	0.02%	$244K	-65 (-0.6%)
135	Vanguard Investments Australia, Ltd.	10,395	0.02%	$242K	—
136	CHOREO, LLC	9,099	0.02%	$212K	NEW
137	VERITY Wealth Advisors	8,815	0.02%	$206K	NEW
138	NewEdge Advisors, LLC	8,660	0.02%	$202K	NEW
139	TSFG, LLC	7,125	0.01%	$166K	—
140	BARTLETT & CO. WEALTH MANAGEMENT LLC	6,320	0.01%	$147K	+21 (+0.3%)
141	CANADA LIFE ASSURANCE Co	5,637	0.01%	$131K	—
142	NISA INVESTMENT ADVISORS, LLC	5,475	0.01%	$128K	+699 (+14.6%)
143	Parkside Financial Bank & Trust	4,484	0.01%	$105K	-121 (-2.6%)
144	Ameritas Investment Partners, Inc.	4,314	0.01%	$101K	—
145	Tower Research Capital LLC (TRC)	2,934	0.01%	$68K	+443 (+17.8%)
146	Versant Capital Management, Inc	2,751	0.01%	$64K	—
147	Parallel Advisors, LLC	2,622	0.01%	$61K	—
148	State of Alaska, Department of Revenue	1,771	0.00%	$41K	—
149	HARBOUR INVESTMENTS, INC.	1,347	0.00%	$31K	—
150	JONES FINANCIAL COMPANIES LLLP	1,053	0.00%	$25K	+1,017 (+2825.0%)
151	Pinnacle Wealth Planning Services, Inc.	1,045	0.00%	$24K	—
152	US BANCORP \DE\	1,002	0.00%	$23K	+17 (+1.7%)
153	SFAM, LLC	992	0.00%	$23K	-4,835 (-83.0%)
154	EverSource Wealth Advisors, LLC	937	0.00%	$22K	-625 (-40.0%)
155	IFP Advisors, Inc	797	0.00%	$19K	+14 (+1.8%)
156	GAMMA Investing LLC	650	0.00%	$15K	+11 (+1.7%)
157	Allworth Financial LP	566	0.00%	$13K	+58 (+11.4%)
158	Covestor Ltd	566	0.00%	$13K	+80 (+16.5%)
159	Essential Partners LLC	540	0.00%	$13K	-667 (-55.3%)
160	NORTHWESTERN MUTUAL WEALTH MANAGEMENT CO	400	0.00%	$9K	—
161	LOS ANGELES CAPITAL MANAGEMENT LLC	369	0.00%	$9K	—
162	PNC Financial Services Group, Inc.	297	0.00%	$7K	+14 (+4.9%)
163	HUNTINGTON NATIONAL BANK	288	0.00%	$7K	NEW
164	Farther Finance Advisors, LLC	232	0.00%	$5K	-32 (-12.1%)
165	SIGNATUREFD, LLC	215	0.00%	$5K	—
166	Clearstead Advisors, LLC	211	0.00%	$5K	NEW
167	DANSKE BANK A/S	200	0.00%	$5K	—
168	Optiver Holding B.V.	178	0.00%	$4K	-8 (-4.3%)
169	Quarry LP	163	0.00%	$4K	-117 (-41.8%)
170	Smartleaf Asset Management LLC	159	0.00%	$4K	—
171	Fortitude Family Office, LLC	155	0.00%	$4K	NEW
172	Larson Financial Group LLC	128	0.00%	$3K	—
173	Rockefeller Capital Management L.P.	123	0.00%	$3K	-142 (-53.6%)
174	Keating Financial Advisory Services, Inc.	76	0.00%	$2K	—
175	True Wealth Design, LLC	64	0.00%	$1K	-28 (-30.4%)
176	Bruce G. Allen Investments, LLC	49	0.00%	$1K	—
177	Torren Management, LLC	44	0.00%	$1K	—
178	FIRST HORIZON CORP	43	0.00%	$1K	—
179	Caitong International Asset Management Co., Ltd	24	0.00%	$560	—
180	Physician Wealth Advisors, Inc.	15	0.00%	$350	NEW
181	TD PRIVATE CLIENT WEALTH LLC	12	0.00%	$280	—
182	SJS Investment Consulting Inc.	5	0.00%	$117	NEW
183	ZIONS BANCORPORATION, NATIONAL ASSOCIATION /UT/	5	0.00%	$117	NEW
184	GHP Investment Advisors, Inc.	1	0.00%	$24	—

Exited since 2026-03-31 (23 filers; largest 23 shown)

JACOBS ASSET MANAGEMENT, LLC	−150,000
JANE STREET GROUP, LLC	−51,428
Corient Private Wealth LLC	−41,087
SUSQUEHANNA INTERNATIONAL GROUP, LLP	−38,533
GAMCO INVESTORS, INC. ET AL	−32,721
MILLENNIUM MANAGEMENT LLC	−31,475
Atom Investors LP	−26,934
JANUS HENDERSON GROUP PLC	−26,232
CWM, LLC	−23,515
nVerses Capital, LLC	−21,243
Assenagon Asset Management S.A.	−17,860
Universal- Beteiligungs- und Servicegesellschaft mbH	−15,821
Amundi	−13,706
CenterBook Partners LP	−13,425
Abacus Wealth Partners, LLC	−11,590
DRW Securities, LLC	−11,467
XTX Topco Ltd	−10,590
Brooklyn Investment Group	−10,216
QUADRANT CAPITAL GROUP LLC	−2,523
MAI Capital Management	−1,491
EASTERN BANK	−758
Root Financial Partners, LLC	−106
NATIONAL BANK OF CANADA /FI/	−3

Large holders from 13D/13G (latest per reporting person, last 2 years)

Filed when a holder crosses 5% or changes materially, so often more current than the quarter-end 13F. Percentages are the filer's own, against the share count they used.

Reporting person	Form	Filed	Event	Shares	% of class
The Vanguard Group	SCHEDULE 13G/A	2026-03-27	2026-03-13	0	0%

Source: SEC Form 13F-HR information tables for the quarter ending 2026-06-30 (filed within 45 days of quarter end; amendments applied; values normalised to dollars), the share count from the company's latest 10-K/10-Q XBRL cover page, and Schedule 13D/13G filings. Each row is a legal 13F filer as filed — related entities (e.g. Vanguard's advisers) are not merged. Retail brokerage accounts are not reported on 13F, so the remainder is mostly retail and insiders.