Baron group files 13G/A: 2,160,463 MEG shares (6.12%)

Rhea-AI Filing Summary

Baron Capital Group and affiliates filed an amended Schedule 13G on Montrose Environmental Group (MEG), reporting beneficial ownership of 2,160,463 shares, or 6.12%, tied to the 09/30/2025 event date.

Within the group, BAMCO reports 1,859,070 shares (5.27%), Baron Capital Management reports 301,393 shares (0.85%), and Baron Discovery Fund reports 1,419,000 shares (4.02%). Voting and dispositive power are reported as shared and not sole across entities. The filing certifies the securities were acquired and are held in the ordinary course and not to change or influence control.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 2)

Montrose Environmental Group, Inc.

(Name of Issuer)

Common Stock

(Title of Class of Securities)

615111101

(CUSIP Number)

09/30/2025

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

SCHEDULE 13G

CUSIP No. 615111101

1

Names of Reporting Persons

BAMCO INC /NY/

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

NEW YORK

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 1,859,070.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,859,070.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,859,070.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

5.27 %

12

Type of Reporting Person (See Instructions)

CO, IA

SCHEDULE 13G

CUSIP No. 615111101

1

Names of Reporting Persons

Baron Capital Group, Inc.

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

NEW YORK

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 2,160,463.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,160,463.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,160,463.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

6.12 %

12

Type of Reporting Person (See Instructions)

CO, HC

SCHEDULE 13G

CUSIP No. 615111101

1

Names of Reporting Persons

Baron Capital Management, Inc.

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

NEW YORK

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 301,393.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 301,393.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

301,393.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

0.85 %

12

Type of Reporting Person (See Instructions)

CO, IA

SCHEDULE 13G

CUSIP No. 615111101

1

Names of Reporting Persons

Ronald Baron

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 2,160,463.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,160,463.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,160,463.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

6.12 %

12

Type of Reporting Person (See Instructions)

IN, HC

SCHEDULE 13G

CUSIP No. 615111101

1

Names of Reporting Persons

Baron Discovery Fund

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

MASSACHUSETTS

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 1,419,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,419,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,419,000.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

4.02 %

12

Type of Reporting Person (See Instructions)

IC

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Montrose Environmental Group, Inc.
(b)	Address of issuer's principal executive offices: 4 PARK PLAZA, SUITE 790, IRVINE, CA, 92614
Item 2.
(a)	Name of person filing: Baron Capital Group, Inc. ("BCG"), BAMCO, Inc. ("BAMCO"), Baron Capital Management, Inc. ("BCM"), Ronald Baron, Baron Discovery Fund ("BDF")
(b)	Address or principal business office or, if none, residence: 767 Fifth Avenue, 49th Floor, New York, NY 10153
(c)	Citizenship: BCG, BAMCO and BCM are New York corporations. Ronald Baron is a citizen of the United States. BDF is a series of a Massachusetts Business Trust.
(d)	Title of class of securities: Common Stock
(e)	CUSIP No.: 615111101
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: 2,160,463
(b)	Percent of class: 6.12 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 0
	(ii) Shared power to vote or to direct the vote: 2,160,463
	(iii) Sole power to dispose or to direct the disposition of: 0
	(iv) Shared power to dispose or to direct the disposition of: 2,160,463
Item 5.	Ownership of 5 Percent or Less of a Class.
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required. The advisory clients of BAMCO and BCM have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the Issuer's common stock in their accounts. To the best of the Filing Persons' knowledge, no such person has such interest relating to more than 5% of the outstanding class of securities.
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	If a parent holding company has filed this schedule, pursuant to Rule 13d-1(b)(ii)(G), so indicate under Item 3(g) and attach an exhibit stating the identity and the Item 3 classification of the relevant subsidiary. If a parent holding company has filed this schedule pursuant to Rule 13d-1(c) or Rule 13d-1(d), attach an exhibit stating the identification of the relevant subsidiary. BAMCO and BCM are subsidiaries of BCG. Ronald Baron owns a controlling interest in BCG.
Item 8.	Identification and Classification of Members of the Group.
	If a group has filed this schedule pursuant to §240.13d-1(b)(1)(ii)(J), so indicate under Item 3(j) and attach an exhibit stating the identity and Item 3 classification of each member of the group. If a group has filed this schedule pursuant to §240.13d-1(c) or §240.13d-1(d), attach an exhibit stating the identity of each member of the group. See Item 3.
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

BAMCO INC /NY/

Signature:	/s/ Ronald Baron
Name/Title:	Chairman and CEO
Date:	11/14/2025

Baron Capital Group, Inc.

Signature:	/s/ Ronald Baron
Name/Title:	Chairman and CEO
Date:	11/14/2025

Baron Capital Management, Inc.

Signature:	/s/ Ronald Baron
Name/Title:	Chairman and CEO
Date:	11/14/2025

Ronald Baron

Signature:	/s/ Ronald Baron
Name/Title:	Individually
Date:	11/14/2025

Baron Discovery Fund

Signature:	/s/ Ronald Baron
Name/Title:	Chairman and CEO
Date:	11/14/2025

FAQ

What stake did Baron report in MEG (Montrose Environmental Group)?

Baron Capital Group and related filers reported 2,160,463 shares, representing 6.12% of MEG common stock.

Which Baron entities are included and what are their holdings?

BAMCO: 1,859,070 shares (5.27%); Baron Capital Management: 301,393 shares (0.85%); Baron Discovery Fund: 1,419,000 shares (4.02%); Ronald Baron and BCG each reflect 2,160,463 shares (6.12%).

Do the Baron entities have sole or shared voting/dispositive power?

They report shared voting and shared dispositive power; sole power is 0.

What is the relevant date for this ownership report?

The Date of Event requiring the filing is 09/30/2025.

Is this a passive ownership filing?

Yes. The certification states the securities were acquired and are held in the ordinary course and not to change or influence control.

What class of securities is covered and what is the CUSIP?

Class: Common Stock; CUSIP: 615111101.