As of November 6, 2026, 2 holders' latest Schedule 13D or 13G filings report owning 5% or more of Trinseo Plc. The largest reported stake is Nut Tree Capital Management, LP's, at 8.3%. 6 filings are on record since July 17, 2025 (Schedule 13G/A, May 15, 2026).
Sell to companies like Trinseo Plc? Enter your website and see 10 with a filed reason to buy from you this month. Free.
Opens in a new tab. No signup.
Key facts
- · Reporting person: BlackRock, Inc. · Sole voting: 77,219 · Shared voting: 0 · Sole dispositive: 105,889 · Shared dispositive: 0 · SCHEDULE 13G/A, 2026-10-27
- · Reporting person: Nut Tree Capital Management, LP · Sole voting: 0 · Shared voting: 3,027,280 · Sole dispositive: 0 · Shared dispositive: 3,027,280 · SCHEDULE 13G/A, 2026-05-15
- · Reporting person: CastleKnight Master Fund LP · Sole voting: 0 · Shared voting: 516,826 · Sole dispositive: 0 · Shared dispositive: 516,826 · SCHEDULE 13G/A, 2026-02-17
- · Reporting person: Charles Schwab Investment Management Inc · Sole voting: 2,091,125 · Shared voting: 0 · Sole dispositive: 2,091,125 · Shared dispositive: 0 · SCHEDULE 13G, 2026-02-12
- · Holder: CastleKnight Master Fund LP · Percent: 7.8% · SCHEDULE 13G/A
Trinseo Plc has 6 Schedule 13D or 13G filings on record since 2025-07-17. 2 holders' latest filing reports 5% or more of common stock. Each figure below is the holder's own, as filed, with the filing linked.
Layoffs on record: 2 filings or notices, latest 2025-12-10 (layoff filings and notices).
Holders
| Holder | Percent | Shares | Latest | Event date |
|---|---|---|---|---|
| Nut Tree Capital Management, LP | 8.3% | 3,027,280 | SCHEDULE 13G/A, 2026-05-15 | 2026-03-31 |
| Charles Schwab Investment Management Inc | 5.8% | 2,091,125 | SCHEDULE 13G, 2026-02-12 | 2025-12-31 |
| CastleKnight Master Fund LP | 1.4% | 516,826 | SCHEDULE 13G/A, 2026-02-17 | 2025-12-31 |
| BlackRock, Inc. | 0.3% | 105,889 | SCHEDULE 13G/A, 2026-10-27 | 2026-09-30 |
Holding shares or following this stake? See who's behind Trinseo Plc and the warning signs.
Free to see. No signup.
Keep reading
More on Trinseo Plc and the records around it.
Trinseo Plc elsewhere on the record
- Layoff notices Dec 2025
- Bankruptcy record
Companies that share a holder
- Nut Tree Capital Management, LP also filed stake reports on 2 other companies: BrightSpire Capital, Inc. (Aug 2026), Xponential Fitness, Inc. (Aug 2025)
- CHARLES SCHWAB INVESTMENT MANAGEMENT INC also filed stake reports on 12 other companies: HAIN CELESTIAL GROUP INC (Aug 2026), MEDIFAST INC (Aug 2026), Service Properties Trust (Aug 2026)
- CastleKnight Master Fund LP also filed stake reports on 17 other companies: Suja Life, Inc. (Aug 2026), Advantage Solutions Inc. (Aug 2026), HAIN CELESTIAL GROUP INC (Aug 2026)
Watch Trinseo Plc
Get an email when Trinseo Plc files again: a new raise, a leadership change, a layoff or an IPO filing. One email first to confirm; nothing else until you click it. At most one a day, one click to stop. Free for up to 3 companies.
Want the whole picture on Trinseo Plc?
Example from a real report (our sample on Target): “Target eliminated approximately 1,800 corporate positions, with around 1,000 employees receiving layoff notices and the remainder accounted for by eliminating open roles.” Source: NBC News
A Full Report on Trinseo Plc: verified, sourced, every claim cited, ready in a few minutes. See pricing.
What the Full Report on Trinseo Plc covers
The Short Answer
Which Company This Is
What They Do, And How The Money Works
Who Runs It, And How To Reach Them
The Money: Funding, Valuation, Runway
Who Pays Them, And Who They Are Up Against
Warning Bells
Sources
8 cited sources found
Plus the sections for what you are deciding, which you pick after ordering.
A real finished report, first screen. Opens in a new tab.
Not ready to order yet? Keep this snapshot.
Sends this preview to you once; we won't add you to any list
Voting and dispositive power, as filed
| Reporting person | Sole voting | Shared voting | Sole dispositive | Shared dispositive | Filing |
|---|---|---|---|---|---|
| Nut Tree Capital Management, LP | 0 | 3,027,280 | 0 | 3,027,280 | SCHEDULE 13G/A, 2026-05-15 |
| Nut Tree Capital Management GP, LLC | 0 | 3,027,280 | 0 | 3,027,280 | SCHEDULE 13G/A, 2026-05-15 |
| Jared R. Nussbaum | 0 | 3,027,280 | 0 | 3,027,280 | SCHEDULE 13G/A, 2026-05-15 |
| Charles Schwab Investment Management Inc | 2,091,125 | 0 | 2,091,125 | 0 | SCHEDULE 13G, 2026-02-12 |
| CastleKnight Master Fund LP | 0 | 516,826 | 0 | 516,826 | SCHEDULE 13G/A, 2026-02-17 |
| CastleKnight Fund GP LLC | 0 | 516,826 | 0 | 516,826 | SCHEDULE 13G/A, 2026-02-17 |
| CastleKnight Management LP | 0 | 516,826 | 0 | 516,826 | SCHEDULE 13G/A, 2026-02-17 |
| CastleKnight Management GP LLC | 0 | 516,826 | 0 | 516,826 | SCHEDULE 13G/A, 2026-02-17 |
| Weitman Capital LLC | 0 | 516,826 | 0 | 516,826 | SCHEDULE 13G/A, 2026-02-17 |
| Aaron Weitman | 0 | 516,826 | 0 | 516,826 | SCHEDULE 13G/A, 2026-02-17 |
| BlackRock, Inc. | 77,219 | 0 | 105,889 | 0 | SCHEDULE 13G/A, 2026-10-27 |
The latest filing identifies Trinseo Plc by CUSIP G9059U107 and gives its principal executive office as 440 EAST SWEDESFORD ROAD, SUITE 301, WAYNE, PA 19087 (SCHEDULE 13G/A, 2026-10-27).
What the percentages are based on
As of March 31, 2026, each of the Reporting Persons may be deemed the beneficial owner of approximately 8.3% of the Shares outstanding. (There were approximately 36,559,868 Shares outstanding as of March 5, 2026, according to the Issuer's annual report on Form 10-K/A, filed April 27, 2026.Nut Tree Capital Management, LP, SCHEDULE 13G/A, 2026-05-15
Timeline
| Filed | Holder | Percent | Filing |
|---|---|---|---|
| 2025-07-17 | BlackRock, Inc. | 6.3% | SCHEDULE 13G |
| 2025-08-14 | CastleKnight Master Fund LP | 7.8% | SCHEDULE 13G/A |
| 2026-02-12 | Charles Schwab Investment Management Inc | 5.8% | SCHEDULE 13G |
| 2026-02-17 | CastleKnight Master Fund LP | 1.4% | SCHEDULE 13G/A |
| 2026-05-15 | Nut Tree Capital Management, LP | 8.3% | SCHEDULE 13G/A |
| 2026-10-27 | BlackRock, Inc. | 0.3% | SCHEDULE 13G/A |
Questions about who owns Trinseo Plc
Who owns Trinseo Plc?
On this page, 2 holders' latest ownership filings report 5% or more of Trinseo Plc: Nut Tree Capital Management, LP (8.3%, Schedule 13G/A, filed 2026-05-15) and Charles Schwab Investment Management Inc (5.8%, Schedule 13G, filed 2026-02-12).
Who are the largest shareholders of Trinseo Plc?
By the share each holder's latest filing reports, the largest holders of Trinseo Plc on this page are Nut Tree Capital Management, LP (8.3%) and Charles Schwab Investment Management Inc (5.8%).
When did Nut Tree Capital Management, LP buy into Trinseo Plc?
The filings give report dates, not purchase dates. The earliest filing from Nut Tree Capital Management, LP on this page is the Schedule 13G/A, filed 2026-05-15, reporting 8.3%. That earliest filing is itself an amendment, which updates an earlier report.
Is this an audit or a full list?
Neither. The ownership list on this page covers only Schedule 13D and 13G filings, which holders make once they own 5% or more of a class of shares (an amendment can report a stake that has since fallen below 5%); 6 such filings are shown here. It is not an audit and not a full cap table: holders who never reached 5% are not listed, and a stake can change after its latest filing.
Tools for this story
Each opens in a new tab, filled in for Trinseo Plc. With no account yet, you sign up free and land on the result.
Where this comes from
Anyone who comes to own more than 5% of a class of a listed company's voting shares has to tell the SEC. A holder who may seek to change or influence the company files Schedule 13D, and has to say in Item 4, "Purpose of Transaction", what it intends to do. A holder with no such intent, such as many index and passive funds, may file the shorter Schedule 13G. Both are amended when the stake changes, including when it falls below 5%.
Every row here is one of those filings, linked to the filing itself. Percentages and share counts are exactly as the holder filed them, for the holder the filing names; an amendment showing a lower figure is shown as filed. Item 4 text is quoted word for word. Where a 13D's Item 4 contains a sentence stating a definite intent to influence the company, that sentence is marked and quoted; the page does not describe the holder or its motives beyond the words it filed. Nothing here is investment advice.