SCHEDULE: Charles Schwab Investment Management Discloses 5.8% Stake in Trinseo PLC

Charles Schwab Investment Management Inc. has reported a 5.8% beneficial ownership stake in Trinseo PLC's Ordinary Shares as of December 31, 2025.

Summary

• CHARLES SCHWAB INVESTMENT MANAGEMENT INC. beneficially owns 2,091,125 Ordinary Shares of Trinseo PLC.
• This ownership represents 5.8% of the total outstanding Ordinary Shares of Trinseo PLC.
• The reporting person, CHARLES SCHWAB INVESTMENT MANAGEMENT INC., has sole voting power and sole dispositive power over all 2,091,125 shares.
• The filing was made pursuant to Rule 13d-1(b) and identifies CHARLES SCHWAB INVESTMENT MANAGEMENT INC. as an investment adviser.
• The date of the event requiring this filing was December 31, 2025.

Sentiment

Score: 5

Explanation: StockSavvy.ai views this as a standard disclosure of a passive institutional ownership stake, providing no direct positive or negative sentiment regarding the issuer's operational performance or strategic direction.

Positives

• The disclosure indicates continued institutional interest in Trinseo PLC's Ordinary Shares by a major investment manager.

Future Outlook

This filing is a disclosure of beneficial ownership and does not contain forward-looking statements or guidance regarding Trinseo PLC's future performance.

Management Comments

• Omar Aguilar, Chief Executive Officer of CHARLES SCHWAB INVESTMENT MANAGEMENT INC., certified that the securities were acquired and are held in the ordinary course of business and not for the purpose of changing or influencing control of the issuer.

Industry Context

StockSavvy.ai notes that Schedule 13G filings provide transparency into significant passive ownership stakes by institutional investors. Such disclosures are standard and indicate that a major investment manager holds a notable position in the company, which can be viewed as a sign of institutional confidence or inclusion in diversified portfolios.

Stakeholder Impact

• Shareholders gain transparency regarding significant institutional ownership in Trinseo PLC.

Key Dates

Keywords

Trinseo PLC, Charles Schwab Investment Management, Schedule 13G, Beneficial Ownership, Ordinary Shares, Institutional Investment, G9059U107