SCHEDULE: D1 Capital Partners Discloses 5.2% Stake in Clean Harbors

D1 Capital Partners L.P. and Daniel Sundheim have disclosed a 5.2% beneficial ownership stake in Clean Harbors Inc., totaling 2,781,882 shares.

Summary

• D1 Capital Partners L.P. and Daniel Sundheim reported beneficial ownership of 2,781,882 shares of Clean Harbors Inc. common stock.
• This represents a 5.2% stake in the company's outstanding common stock.
• The shares were acquired and are held in the ordinary course of business, not for the purpose of changing or influencing control of Clean Harbors Inc.
• The percentage is calculated based on 53,431,835 shares of Common Stock reported to be outstanding as of October 24, 2025.

Sentiment

Score: 7

Explanation: StockSavvy.ai views this as a moderately positive development, as a significant stake by a reputable institutional investor like D1 Capital Partners can signal confidence in Clean Harbors Inc.'s valuation and future prospects, without indicating any immediate operational changes.

Positives

• A significant institutional investor, D1 Capital Partners, has taken a 5.2% stake in Clean Harbors Inc., potentially signaling confidence in the company's long-term prospects.
• The investment is stated to be in the ordinary course of business, suggesting a passive, long-term holding rather than an activist position.

Negatives

• No specific negative information about Clean Harbors Inc. is disclosed in this beneficial ownership filing.

Risks

• The filing itself does not detail specific risks related to Clean Harbors Inc.'s operations or financial health. It only states the nature of the beneficial ownership.

Future Outlook

NA

Industry Context

StockSavvy.ai notes that the disclosure of a significant stake by a prominent investment firm like D1 Capital Partners in Clean Harbors Inc. could be interpreted as a positive signal for the environmental and industrial waste management sector. This sector often sees interest from institutional investors due to its essential services and potential for long-term growth driven by regulatory compliance and sustainability initiatives.

Stakeholder Impact

• Shareholders: May view the entry of a significant institutional investor as a positive indicator of the company's value and potential for future growth.
• Management: The presence of a large, passive institutional investor typically encourages management to focus on long-term value creation.

Next Steps

• The reporting persons will be responsible for timely filing of subsequent amendments to this Schedule 13G.

Key Dates

Recommendation

The disclosure of a 5.2% stake by D1 Capital Partners in Clean Harbors Inc. is a positive signal, indicating institutional confidence. However, as a passive investment, it does not inherently suggest immediate catalysts for significant price appreciation or depreciation. A "hold" recommendation reflects the stability implied by a long-term institutional investor without new operational or financial news to warrant a stronger buy or sell.

Keywords

Clean Harbors Inc., D1 Capital Partners, Daniel Sundheim, Beneficial Ownership, Schedule 13G, Institutional Investment, Common Stock, Environmental Services, Waste Management