8-K

UNITED STATESSECURITIES AND EXCHANGE COMMISSIONWASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Montrose Environmental Group, Inc.

(Exact name of Registrant as Specified in Its Charter)

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 8.01 Other Events.

On July 1, 2025, Montrose Environmental Group, Inc. (the “Company”) voluntarily redeemed in full all issued and outstanding shares of the Company’s Series A-2 Preferred Stock (the “A-2 Preferred”), which were held by OCM Montrose II Holdings, L.P (the “Holder”). The Stated Value, as defined in the certificate of designation governing the A-2 Preferred (the “Certificate of Designations”), of the remaining outstanding shares of A-2 Preferred at the time of redemption was $62.2 million, which was paid in cash on July 1, 2025 from cash on hand and borrowings under the Company’s credit facility. Following this redemption, no shares of the A-2 Preferred stock remain outstanding, and the Holder no longer has the right to appoint a member to the Company’s Board of Directors.

The foregoing summary is qualified in its entirety by reference to the complete text of the Certificate of Designations, a copy of which is incorporated by reference as Exhibit 3.3 to the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2024 filed with the Securities and Exchange Commission on March 3, 2025.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.