SCHEDULE: William Blair Discloses 3.7% Stake in Montrose Environmental

William Blair Investment Management, LLC has reported a 3.7% beneficial ownership stake in Montrose Environmental Group, Inc. as of September 30, 2025.

Summary

• William Blair Investment Management, LLC holds beneficial ownership of 1,315,018 shares of Montrose Environmental Group, Inc. common stock.
• This ownership represents 3.7% of the total class of securities.
• The firm exercises sole voting power over 1,052,190 shares and sole dispositive power over all 1,315,018 shares.
• This filing is an Amendment No. 2 to a Schedule 13G, indicating an update to a previously reported beneficial ownership position.
• William Blair Investment Management, LLC is classified as an investment adviser, and the securities were acquired and are held in the ordinary course of business, not for the purpose of changing or influencing control of the issuer.

Sentiment

Score: 5

Explanation: The filing is a routine disclosure of beneficial ownership by an investment adviser. It indicates a passive stake and does not inherently convey positive or negative sentiment regarding the issuer's performance or prospects. The future 'Date of Event' is unusual but does not alter the neutral sentiment of the disclosure itself.

Future Outlook

NA

Industry Context

NA

Key Dates

Keywords

Montrose Environmental Group, William Blair Investment Management, Schedule 13G, Beneficial Ownership, Common Stock, Investment Adviser, Institutional Ownership