UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K (Mark One) ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM TO Commission File Number 001-39394 Montrose Environmental Group, Inc. (Exact name of Registrant as specified in its Charter) (State or other jurisdiction of incor ...

Financial Data and Key Metrics Changes - The company reported a total revenue increase of 20.2% to $162.8 million in Q4 2023 and a full-year revenue increase of 17.5% to $615.4 million [44] - Consolidated adjusted EBITDA for Q4 2023 increased by 12.2%, driven by higher revenues, with full-year consolidated adjusted EBITDA at $78.6 million, or 12.6% of revenue, compared to $66.2 million, or 12.2% in the prior year [45][66] - Adjusted net income per share increased by 24% to $1.07 for the full year, up from $0.86 in 2022, primarily due to higher revenues and stronger adjusted EBITDA [94] Business Line Data and Key Metrics Changes - The Assessment, Permitting, and Response (AP&R) segment saw a 24% organic revenue growth, while the Measurement and Analysis (M&A) segment experienced a 17% organic revenue growth, attributed to higher demand for advisory services and strong performance in lab and field services [31][39] - The Remediation and Reuse (R&R) segment's revenue growth was primarily driven by the acquisition of Matrix, but faced declines from certain large water treatment projects and a strategic shift towards higher-margin services [40][68] Market Data and Key Metrics Changes - The company noted a significant uptick in activity globally, particularly in Europe, due to anticipatory actions by clients related to PFAS regulations [2] - The U.S. EPA's focus on PFAS and new regulations is expected to create substantial opportunities for the company, as it aims to regulate emerging contaminants at permitted waste facilities [89] Company Strategy and Development Direction - The company is focused on expanding its advisory services, which were previously underrepresented, and is seeing success in building deeper client relationships across multiple service lines [6][8] - Acquisitions remain a core part of the company's strategy, with five acquisitions closed in 2023 and two more in early 2024, enhancing service capabilities and geographic reach [55][56] Management's Comments on Operating Environment and Future Outlook - Management expressed optimism about the outlook for advisory services in 2024, expecting continued strong organic growth and margin expansion [39][72] - The company anticipates a revenue increase in each quarter of 2024, with a focus on maintaining a healthy cash flow conversion rate above 50% [100][72] Other Important Information - The company achieved a cash flow from operations of $56 million in 2023, more than double the prior year, providing flexibility for investments in M&A and R&D [37] - The company ended 2023 with a net leverage ratio of 1.9 times and a strong liquidity position of approximately $150 million [70] Q&A Session Summary Question: Can you provide more detail on the two acquisitions, Epic and Two Dot? - Management highlighted that Epic brings environmental expertise and credibility in the Australian market, complementing treatment technology efforts, while Two Dot enhances capabilities in the Rocky Mountain region, where the company is underrepresented [3][4] Question: What is the expected cash flow conversion for 2024? - The company expects to convert 50% to 60% of adjusted EBITDA into operating cash flow, likely on the higher end of that range due to improved working capital management [14] Question: Are there any tough comparisons for 2024 by segment? - Management noted that Q1 2024 has the toughest comparables on an EBITDA basis due to a large emergency response project in the prior year, but expects revenue growth across all quarters [16][17] Question: How is the integration of Matrix going? - The integration is progressing well, with margins nearly doubling since acquisition, and cross-selling efforts are expected to manifest more fully in 2024 [141]

Exhibit 99.1 MONTROSE ENVIRONMENTAL GROUP ANNOUNCES FOURTH QUARTER AND FULL YEAR 2023 RESULTS - Record Full Year Revenue and Cash Flow from Operations - - Net Loss of $30.9 million; Basic and Diluted Net Loss Per Share of $1.57 - - Significant Increase in Diluted Adjusted Net Income Per Share 1 - - Record Full Year Consolidated Adjusted EBITDA1 - - Expansion in Segment Level and Consolidated Adjusted EBITDA1 as Percent of Revenue for Full Year - - Continued Success Consolidating Fragmented Industry with Hig ...

Montrose Environmental Group, Inc. (NYSE:MEG) Q3 2023 Earnings Conference Call November 8, 2023 8:30 AM ET Company Participants Rodny Nacier - Investor Relations Vijay Manthripragada - President and Chief Executive Officer Allan Dicks - Chief Financial Officer Conference Call Participants Tim Mulrooney - William Blair Jim Ricchiuti - Needham & Company David Ridley-Lane - Bank of America Wade Suki - Capital One Stephanie Yee - JP Morgan Operator Good morning and welcome to the Montrose Environmental Group, I ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-39394 Montrose Environmental Group, Inc. (Exact Name of Registrant as Specified in its Charter) | Delaware | 46-4195044 | | - ...

Included in this presentation and the accompanying oral presentation are certain financial measures that are not calculated in accordance with U.S. generally accepted accounting principles ("GAAP") designed to supplement, and not substitute, Montrose's financial information presented in accordance with GAAP. The non-GAAP measures as defined by Montrose may not be comparable to similar non-GAAP measures presented by other companies. The presentation of such measures, which may include adjustments to exclude ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-39394 Montrose Environmental Group, Inc. (Exact Name of Registrant as Specified in its Charter) WASHINGTON, DC 20549 | Delaware | 46-4195044 | | --- | ...

Financial Data and Key Metrics Changes - The company's Q2 2023 revenue was $159.1 million, representing a 13.7% increase compared to the prior year quarter, while year-to-date revenues increased by 5.8% to $290.5 million [20][78] - Consolidated adjusted EBITDA for Q2 2023 was $21.2 million, or 13.3% of revenue, compared to $15.6 million, or 11.2% of revenue in the prior year quarter, reflecting a significant year-over-year improvement [105] - Year-to-date cash flow from operating activities was $24.5 million, improving from a cash used in operating activities of $2.9 million in the prior year period [107] Business Segment Performance Changes - In the Assessment Permitting and Response segment, revenues increased by 22.7% year-over-year to $61.4 million, driven primarily by organic growth and acquisitions [106] - The Measurement and Analysis segment saw revenue growth of 18.5% to $50.1 million, attributed to strong organic growth and benefits from acquisitions [80] - The Remediation and Reuse segment's revenues were flat year-over-year at $47.6 million, with the Matrix acquisition offsetting declines in other areas [28] Market Data and Key Metrics Changes - Demand for environmental response services provided by CTEH remained elevated due to several prominent environmental emergencies, contributing to higher revenues [21][74] - The EPA's new rules targeting methane emissions are expected to support incremental demand for emissions measurement and monitoring services [24] - The recent regulations regarding PFAS are anticipated to increase future demand for consulting and testing services [76][102] Company Strategy and Industry Competition - The company is focusing on optimizing adjusted EBITDA margins while maintaining long-term organic growth opportunities [69] - Investments in technology and R&D are expected to enhance the company's competitive position in the environmental services market [70] - The company is pivoting its renewable energy business model to focus on higher-margin opportunities, which may temporarily depress revenue growth in the short term [23] Management's Comments on Operating Environment and Future Outlook - Management expressed optimism about the momentum in the business and the ability to sustainably create shareholder value due to the growing need for differentiated environmental solutions [31] - The company raised its full-year revenue outlook to a range of $590 million to $640 million, up from the previous guidance of $550 million to $600 million [109] - Management noted that while quarterly results are important, the business should be assessed on an annual basis due to the nature of demand for environmental services [72] Other Important Information - The company published its 2022 sustainability report, responding to investor requests for more detailed reporting on sustainability efforts [8] - The acquisition of Matrix is expected to improve margins and create cross-selling opportunities, with a target to increase margins to low- to mid-teens by the end of 2024 [28][118] Q&A Session Summary Question: Expected contribution from Matrix and legacy Montrose - Management indicated that Matrix runs at $75 million to $80 million of revenue annually, with a significant portion of EBITDA expected to contribute to updated guidance [33] Question: Comments on PFAS project timing shifts - Management clarified that project timelines have shifted due to client assessments of new regulations, impacting the execution of projects [125] Question: Outlook for the ECT2 business - Management expects the ECT2 business to be flat for the year, with a long-term bullish outlook despite short-term revenue declines [115] Question: SG&A expectations moving forward - Management expects SG&A to remain at or below 6% for the full year, with modest increases anticipated in the future [54] Question: Revenue synergies from Matrix acquisition - Management highlighted that the Matrix acquisition is expected to drive revenue synergies through cross-utilization of staff and expertise [152]

Safe Harbor Included in this presentation and the accompanying oral presentation are certain financial measures that are not calculated in accordance with U.S. generally accepted accounting principles ("GAAP") designed to supplement, and not substitute, Montrose's financial information presented in accordance with GAAP. The non-GAAP measures as defined by Montrose may not be comparable to similar non-GAAP measures presented by other companies. The presentation of such measures, which may include adjustments ...

Financial Data and Key Metrics Changes - Total revenue for Q1 2023 was $131.4 million, a decrease from $134.7 million in the prior year quarter, primarily due to lower demand for COVID-19-related services and project timing in the remediation and reuse segment [16][17] - Consolidated adjusted EBITDA was $16.6 million, representing 12.6% of revenue, an increase of 15.2% from $14.4 million in the prior year, with adjusted EBITDA margins improving from 11.2% to 12.8% [17][22] - The company raised its full-year 2023 EBITDA outlook to a range of $70 million to $76 million, up from the previous range of $68 million to $74 million, indicating low double-digit growth and margin expansion [22] Business Segment Performance - In the Assessment Permitting and Response segment, revenue increased 14.5% year-over-year to $52.2 million, driven by organic growth and acquisitions, with adjusted EBITDA increasing 48.2% to $14.3 million, reflecting a margin of 27.3% [39] - The Measurement and Analysis segment saw a revenue increase of 7% to $42.5 million, primarily due to strong organic growth, with adjusted EBITDA margin rising to 15.6% from 13.7% in the prior year [40] - The Remediation and Reuse segment experienced a revenue decline to $36.7 million from $49.3 million in the prior year quarter, attributed to the winding down of high-value projects, although this was partially offset by revenues from acquisitions [1][6] Market Data and Key Metrics Changes - The U.S. EPA's focus on PFAS and methane emissions is expected to drive demand for the company's services, particularly in environmental consulting and testing [8][9][10] - The company is well-positioned to assist clients in navigating the evolving regulatory landscape, which is expected to enhance demand for its services [11] Company Strategy and Industry Competition - The company is focusing on acquisitions to enhance its service offerings, with a reduced cadence last year due to strong organic growth, but expects to capitalize on its M&A pipeline this year [2] - Investments in R&D are anticipated to yield significant returns, particularly in greenhouse gas measurement, PFAS remediation, and renewable energy sectors [43] Management's Comments on Operating Environment and Future Outlook - Management expressed confidence in the company's ability to solve environmental challenges and create value for shareholders, citing strong cash flow and a robust balance sheet [3][13] - The company remains insulated from political and economic swings, with a strong outlook for organic growth across its service lines despite anticipated moderation in certain segments [3][32] Other Important Information - The company’s leverage ratio as of March 31, 2023, was 1.4x, with minimal exposure to rising interest rates due to cash reserves and interest rate swaps [41] - The Series A2 preferred stock has no maturity date, providing flexibility in capital structure [21] Q&A Session Summary Question: Can you provide details on the Matrix Solutions acquisition? - The acquisition is in the process of shareholder vote and is expected to close in the second quarter, but it will not materially impact the overall profile as CTEH did [46][47] Question: What is the market opportunity in Canada? - The company sees significant opportunities in Canada due to favorable environmental policies and expects strong client-based opportunities across both Canada and the U.S. [48][62] Question: How durable are the margins in the Assessment and Permitting segment? - The margins are expected to be durable, with a run rate of $75 million to $95 million in revenue and approximately 25% EBITDA margins [51] Question: Should we expect growth in the remediation and reuse revenue for the full year? - The company anticipates flat growth for 2023 compared to 2022, with a strong outlook for 2024 to 2025 [54][55] Question: Is there any sensitivity around CapEx projects in the assessment and permitting area? - The company is not significantly exposed to discretionary spending and remains confident in its fundamental work despite broader economic uncertainties [69]