Trinseo PLC - Ordinary Shares, par value $0.01 per share (TSE) Institutional Ownership

13F Institutional Holders and Ownership History from Q3 2019 to Q4 2025

Type / Class: Equity / Ordinary Shares, par value $0.01 per share
Symbol: TSE on NYSE
Shares outstanding: 36,916,143
Price per share: $0.48
All holders as of 31 Dec 2025: Q4 2025
Total 13F shares: 24,748,800
Total reported value: $12,300,682
% of total 13F portfolios: 0%
Share change: -1,835,735
Value change: -$9,970,261
Number of holders: 70
Price from insider filings: $0.48

Reported Shares, Excluding Options vs Price

Reported Value, Excluding Options

Total Investors

Significant Owners of Trinseo PLC - Ordinary Shares, par value $0.01 per share (TSE) based on Schedule 13D/G filings

Filer	Ownership	Change %	Holdings Value	Net Change	Nb Shares	Change %	Reporting Name	Report Period
BlackRock, Inc.	6.3%		$8,456,719		2,255,125		BlackRock, Inc.	30 Jun 2025
CHARLES SCHWAB INVESTMENT MANAGEMENT INC	5.8%		$1,693,811		2,091,125		CHARLES SCHWAB INVESTMENT MANAGEMENT INC	31 Dec 2025
CastleKnight Master Fund LP	1.4%	-80%	$418,629	-$1,822,014	516,826	-81%	CastleKnight Master Fund LP	31 Dec 2025

As of 31 Dec 2025, 70 institutional investors reported holding 24,748,800 shares of Trinseo PLC - Ordinary Shares, par value $0.01 per share (TSE). This represents 67% of the company’s total 36,916,143 outstanding shares.

Top 25 Institutional Shareholders

The largest institutional shareholders of Trinseo PLC - Ordinary Shares, par value $0.01 per share (TSE) together control 66% of the company’s outstanding shares — a level of ownership often associated with strong institutional conviction and long‑term capital commitment.

Institution	Ownership %	Shares Held	Share Change %	Portfolio %	Holdings Value
M&G PLC	21%	7,625,044	0%	0.02%	$3,789,647
Nut Tree Capital Management, LP	9.5%	3,500,000		0.33%	$1,739,500
BlackRock, Inc.	6.5%	2,413,178	+1.8%	0%	$1,199,349
CHARLES SCHWAB INVESTMENT MANAGEMENT INC	5.7%	2,091,125	+39%	0%	$1,039,289
Owl Creek Asset Management, L.P.	4.5%	1,669,952	0%	0.1%	$829,966
ICON ADVISERS INC/CO	2.7%	1,000,000	0%	0.11%	$497,000
GEODE CAPITAL MANAGEMENT, LLC	2.3%	841,720	-0.01%	0%	$418,419
VANGUARD GROUP INC	2.1%	762,828	+0.95%	0%	$379,126
GOLDMAN SACHS GROUP INC	1.6%	580,623	+361%	0%	$288,569
MORGAN STANLEY	1.5%	536,422	+18%	0%	$266,601
CastleKnight Management LP	1.4%	516,826	-79%	0.01%	$256,863
GSA CAPITAL PARTNERS LLP	1.4%	511,342		0.02%	$254,000
STATE STREET CORP	1.3%	478,033	+13%	0%	$237,582
LAKEWOOD CAPITAL MANAGEMENT, LP	0.76%	281,279	0%	0.01%	$139,796
RENAISSANCE TECHNOLOGIES LLC	0.75%	276,100	-12%	0%	$137,222
NORTHERN TRUST CORP	0.67%	245,801	-8.5%	0%	$122,163
UBS Group AG	0.5%	184,497	-7.7%	0%	$91,695
Alta Fundamental Advisers LLC	0.41%	152,974	0%	0.04%	$76,028
DEUTSCHE BANK AG\	0.34%	125,610	+336%	0%	$62,805
DIMENSIONAL FUND ADVISORS LP	0.27%	98,606	-16%	0%	$49,071
Bank of New York Mellon Corp	0.22%	80,740	-0.81%	0%	$40,128
Invesco Ltd.	0.19%	70,320	-47%	0%	$34,949
FMR LLC	0.18%	67,624	+34%	0%	$33,609
BARCLAYS PLC	0.14%	53,255	+11%	0%	$26,467
Kohmann Bosshard Financial Services, LLC	0.12%	44,605	0%	0%	$22,169

Institutional Holders of Trinseo PLC - Ordinary Shares, par value $0.01 per share (TSE) across Reporting Periods

Period	Reported Shares, Excl. Options	Value, Excl. Options	Value Change	Puts Notional Value	Calls Notional Value	Price (Median)	Investors
2025 Q4	24,748,800	$12,300,682	-$9,970,261			$0.50	70
2025 Q3	26,848,081	$60,426,503	-$2,561,222	$45,741	$0	$2.35	74
2025 Q2	27,680,017	$85,444,543	+$6,908,226	$0	$73,632	$3.12	80
2025 Q1	25,205,020	$95,192,408	+$227,708	$20,608	$162,288	$3.68	85
2024 Q4	24,965,599	$126,559,235	+$8,302,489	$70,380	$418,710	$5.10	95
2024 Q3	22,908,998	$116,234,027	-$3,240,258	$26,061	$480,851	$5.11	71
2024 Q2	25,261,519	$55,987,559	-$9,396,897	$137,214	$3,234	$2.31	95
2024 Q1	27,408,421	$105,280,091	-$21,098,784	$403,704	$423,360	$3.78	104
2023 Q4	29,143,643	$241,188,653	-$5,907,974	$976,779	$1,216,998	$8.37	126
2023 Q3	29,752,666	$241,775,134	-$41,807,613	$2,102,958	$1,703,445	$8.17	144
2023 Q2	32,802,961	$418,132,080	-$12,498,617	$4,273,591	$2,245,124	$12.67	140
2023 Q1	33,318,012	$695,818,411	+$11,139,887	$4,822,605	$1,513,710	$20.85	165
2022 Q4	32,790,143	$747,004,231	+$30,441,354	$4,335,339	$826,644	$22.71	178
2022 Q3	31,874,971	$581,417,571	-$50,356,911	$4,033,000	$1,813,000	$18.32	163
2022 Q2	34,023,738	$1,305,500,527	-$11,045,976	$2,309,000	$22,389,000	$38.46	183
2022 Q1	34,508,974	$1,654,900,596	-$28,237,350	$3,451,000	$3,920,000	$47.92	181
2021 Q4	35,066,439	$1,836,288,499	+$1,805,342,295	$4,742,000	$11,321,000	$52.46	171
2021 Q3	232,117	$12,490,120	+$12,441,532			$53.97	14
2021 Q2	900	$53,856				$59.84	1
2021 Q1	900	$57,303	-$1,000			$63.67	1
2020 Q4	916	$47,089				$56.86	2
2020 Q3	900	$23,076				$25.64	1
2020 Q2	900	$19,944	+$19,944			$22.16	1
2019 Q4	0	$0	-$32,728			$0.48	0
2019 Q3	762	$32,728	+$32,728			$42.95	1