MESSAGE FROM OUR FOUNDER

AND CHIEF EXECUTIVE OFFICER

Dear Fellow Stockholders,

MESSAGE FROM OUR BOARD CHAIR

Since joining the CoStar Group Board of Directors in 2019, I have had the privilege to serve with a dedicated and collaborative group of directors overseeing the tremendous growth and continued innovation at the Company. We are in the midst of another transformative growth phase as Costar Group continues to develop our marketplaces from commercial and multi-family to residential, while also driving international expansion.

I am honored to take on this role as Board Chair and excited for the tremendous value creation opportunity ahead. On behalf of the Board and leadership team, I thank Michael Klein, Chris Nassetta, and Laura Cox Kaplan for their dedication to CoStar Group and considerable contributions to the business. Michael has been instrumental to CoStar Group’s success since the founding of the Company, including helping to develop the strategic direction of the business and chart the course for CoStar Group’s tremendous growth and value creation. Similarly, Chris and Laura have played critical roles overseeing the expansion and evolution of our platforms, the development of our operational model and the creation of the Company’s strong financial foundation. Michael, Chris and Laura have exemplified what it means to be thoughtful, engaged and highly collaborative Board members and advocates for stockholders.

The retirement of Michael, Chris and Laura has provided us with an opportunity for Board refreshment, to gain new perspectives in the boardroom from qualified and independent new directors. I am pleased to welcome three new directors to the Board, John Berisford, Rachel Glaser and Christine McCarthy. My esteemed colleagues bring with them a range of experience that will enhance the abilities of the Board and provide critical skill sets to the Company during what we believe will be a prosperous and pivotal chapter in CoStar Group’s history.

The Company’s dedication to Board refreshment is just one of the many ways in which CoStar Group is an industry leader. In the last two years alone, the Board has added four new directors, a 50% refreshment rate. All of our directors, other than our founder and Chief Executive Officer, are independent. All have extensive C-Suite leadership experience. The average tenure of our independent director nominees is currently 3 years, down from 12 years in 2024.

In April 2025, the Board adopted a retirement policy providing that no director will be nominated for election or re-election to the Board if he or she would be 75 or older at the time of the election, unless the Nominating & Corporate Governance Committee and Board determine that the continued service of the director on the Board would be of benefit to the Company.

With these Board refreshment initiatives, I am excited to serve as Board Chair for a group of some of the foremost experts and advisors available to a best-in-class company.

Sincerely,

		LOUISE S. SAMS Board Chair, CoStar Group, Inc.

NOTICE OF 2025 ANNUAL

MEETING OF STOCKHOLDERS

THURSDAY, JUNE 26, 2025 | 10:00 A.M., EASTERN TIME

Exclusively online at www.virtualshareholdermeeting.com/CSGP2025

Review your proxy statement and vote in one of three ways:

Internet   Visit the website on your proxy card

By Telephone   Call the telephone number on your proxy card

By Mail   Sign, date and return your proxy card in the enclosed envelope

IMPORTANT NOTICE REGARDING THE AVAILABILITY OF PROXY MATERIALS FOR THE STOCKHOLDER MEETING TO BE HELD ON JUNE 26, 2025: The Notice of Meeting and this Proxy Statement, as well as our Annual Report to Stockholders (the “2024 Annual Report”), are available on our corporate website at https://investors.costargroup.com/financials-filings. We are furnishing proxy materials to some of our stockholders through the Internet instead of through the mail. On or about April 30, 2025, we mailed to stockholders as of the record date a Notice of Internet Availability of Proxy Materials (the “Notice”). The Notice tells you how to access this Proxy Statement and our 2024 Annual Report, as well as how to submit your proxy over the Internet. If you received the Notice and would still like to receive a printed copy of our proxy materials, please follow the instructions in the Notice.

TABLE OF CONTENTS

GLOSSARY OF TERMS

The following abbreviations or acronyms used in this Proxy Statement are defined below:

Proxy Highlights

OUR

VALUES

2024 Financial Highlights

(1) Adjusted EBITDA is a non-GAAP measure. See Appendix A for a reconciliation of Adjusted EBITDA to Net Income and for a discussion of management’s use of non-GAAP measures and other operating metrics.

Corporate Responsibility Highlights

2024 was a year of continued progress in corporate responsibility and thoughtful governance. We added Task Force on Climate-related Financial Disclosures (TCFD) reporting to our 2024 Corporate Responsibility Report, which assess CoStar Group’s climate risks and opportunities. In addition, we received approval from Science Based Target Initiative (SBTi) on our near-term and Net Zero science-based targets. We look forward to reporting against our targets in the years to come.

*Using an estimate of a 10-mile round trip and EPA estimated emissions of an average passenger vehicle.

Human Capital Management

We measure our success in providing a positive work environment through a yearly Employee Engagement Survey administered by a third-party agency. Surveying our employees each year gives us an opportunity to see where we are excelling and what areas need improvement. The results of these surveys have helped us innovate how we look at employee programs, benefits, environment, and our internal protocols.

In 2024, 90% of employees participated in the survey, and we celebrate our outstanding employee engagement scores, with an overall engagement score of 80%. We are proud to have a highly engaged workforce, reflected in our average monthly employee retention rate of 99%.

2024 Stockholder Engagement

As part of our investor outreach, our management continues to regularly communicate with our investor base about the Company’s plans and associated investments. Management communicated with investors throughout the year through quarterly press releases and conference calls that were recorded and made available on the Company’s website, as well as by participating in hundreds of in-person meetings and presentations at investor conferences. The Company also conducted hundreds of additional investor telephone calls throughout the year. The Company actively communicates and discusses with investors our progress towards stated strategic initiatives, including corporate governance and Corporate Responsibility initiatives, as well as expected investments and the rationale and expected returns on those investments. In 2024, our management engaged with our active stockholders as follows:

Investor Day

In December 2024, we conducted an Investor Day at our Richmond, Virginia campus. The Investor Day provided an opportunity for our Chief Executive Officer and senior management to present an update to investors on our vision and strategy, including an overview of our various product lines. We hosted 40 in person attendees and more than 750 via web conference. Our Investor Day was an important opportunity to demonstrate the breadth and depth of our leadership team, offer a deeper understanding of the opportunities ahead and build confidence in CoStar Group’s long-term revenue growth strategy.

Total Shareholder Return

Proposals to be Voted on and Board Voting Recommendations

Corporate Governance Highlights

		BOARD STRUCTURE AND INDEPENDENCE   •  Our Board reflects a broad range of skill set, experience, and background.   •  All directors are independent except for our CEO.   •  Executive sessions of the independent directors are held at Board meetings without    management present.   •  All of our directors are elected annually by our stockholders; we do not have a classified or    staggered board.
		BOARD OVERSIGHT   •  Our Board oversees the Company’s strategy and annual business plan and risk management.   •  Our Board oversees Corporate Responsibility matters, including climate-related risks and opportunities.   •  Our Nominating and Corporate Governance Committee oversees annual political contributions.   •  Our Audit Committee oversees the integrity of the Company’s financial statements.   •  Our Audit Committee oversees the Company’s cybersecurity risk profile.   •  Our Compensation Committee oversees risk in compensation policies and practices.   •  Our new Capital Allocation Committee supports the Board’s and management’s comprehensive review of the Company’s capital structure, capital allocation priorities and financial targets.
		STOCKHOLDER RIGHTS   •  The holders of 25% of our issued and outstanding shares entitled to vote can request a special meeting.   •  We have a majority voting standard for the election of directors in uncontested elections.   •  Our governance documents do not contain provisions requiring a supermajority stockholder vote on any issue.   •  We do not maintain a stockholder rights plan or “poison pill.”   •  We adopted a proxy access right for holders of 3% of our common stock for at least three years to nominate a specified number of directors for inclusion in the proxy statement for our annual meeting.
		CORPORATE GOVERNANCE PRACTICES   •  We prohibit hedging and pledging transactions in our securities by directors and officers.   •  We engage with our stockholders to solicit their feedback regarding issues, including corporate governance and have taken actions to implement their feedback.   •  We have adopted share ownership requirements for directors and officers.   •  We have a clawback policy for cash and equity awards in the event of certain financial restatements.   •  We have adopted a Code of Business Conduct and Ethics for directors, officers and employees with an annual certification requirement.   •  In 2025, we amended our Human Rights Policy specifically prohibiting the use of child labor in our business.   •  In 2025, we adopted a Board Retirement Policy enforcing retirement at age 75, with possibility for waiver.

Our Board of Directors

The below summarizes information about our director nominees and their Audit, Compensation, and Nominating and Corporate Governance Board committee assignments. Our director nominees possess a broad range of skills, experiences, backgrounds, and viewpoints that we believe are essential to an effective Board. Detailed information about each director nominee’s qualifications, skills, experiences, and expertise can be found beginning on page 18.

2025 Director Nominees

The table below provides current membership information for each of the Audit, Compensation, and Nominating and Corporate Governance Board Committees.

Director Nominee Experience Highlights

Our director nominees have a broad range of skills and experiences, including some or significant experience in the following:

		COMMERCIAL REAL ESTATE				PUBLIC COMPANY       GOVERNANCE				GLOBAL BUSINESS
		FINANCIAL ACCOUNTING AND REPORTING				LEGAL, PUBLIC POLICY, AND REGULATORY				BUSINESS DEVELOPMENT AND M&A
		TALENT MANAGEMENT       AND EXECUTIVE COMPENSATION				MARKETING AND SALES				RISK MANAGEMENT
		SENIOR MANAGEMENT AND LEADERSHIP				CYBERSECURITY AND DATA PRIVACY				CORPORATE RESPONSIBILITY AND SUSTAINABILITY

_⬛ VERY SKILLED/EXPERIENCED  _⬛ SOME SKILL/EXPERIENCE  _⬛ NO EXPERIENCE

Board Composition

Executive Compensation Highlights

Our Compensation Committee has designed our executive compensation program to closely align executive compensation with Company performance and stockholder interests. The Compensation Committee achieves this alignment by allocating the majority of our executive officers’ target compensation to performance-based incentive compensation. In particular, we grant performance-based equity awards that directly link the value of annual equity awards to financial performance measures and the value of long-term equity awards to multi-year financial performance and TSR. The primary elements of our 2024 executive compensation program and the portions of such executive compensation that are performance-based are highlighted below.

Board Refreshment

We regularly evaluate the Board’s composition to ensure that we have the right mix of skill and experience to oversee the ongoing execution of our strategy as we work to enhance stockholder value. We also regularly engage with all of our stockholders to understand their perspectives on many important topics. Our Board values the views of our stockholders regarding board composition and, in response to stockholder input, has made board refreshment a priority.

As previously disclosed, as a result of the Board’s ongoing refreshment and succession planning process and in accordance with support agreements we entered into with certain stockholders, the Board elected each of John Berisford, Rachel Glaser and Christine McCarthy as new Board members, effective April 6, 2025. Each of these new directors has been determined to (i) be an “independent director” under Nasdaq listing standards and (ii) have no transactions with “related persons,” as defined under the Exchange Act. These new independent directors bring significant experience and expertise relevant to our business and strategy, and we are confident they will help us extend our long track record of creating value for stockholders. Ms. Glaser is a seasoned executive with considerable financial expertise and relevant marketplace experience. Ms. McCarthy is a recognized corporate finance leader with over 30 years of experience. Mr. Berisford is an accomplished executive who most recently served as President of S&P Global Ratings.

Also in April 2025, each of Michael Klein, Chris Nassetta and Laura Cox Kaplan retired from the Board. Mr. Klein has been instrumental to our success since co-founding the Company, including helping to develop the strategic direction of the business and chart the course for our tremendous growth and value creation. Similarly, Mr. Nassetta and Ms. Cox Kaplan have played critical roles overseeing the expansion and evolution of our platforms, the development of our operational model and the creation of our strong financial foundation. The Board thanks them for their years of valuable service to the Board and the Company.

The Board also appointed Louise Sams as the Board Chair, replacing Mr. Klein. Ms. Sams’ broad range of business and legal experience, including as general counsel of a large television and media conglomerate, and extensive public company board experience, will be incredibly valuable in her new role as Board Chair.

COSTAR GROUP, INC.

PROXY STATEMENT

ANNUAL MEETING OF STOCKHOLDERS

TO BE HELD ON THURSDAY, JUNE 26, 2025

The Board of Directors (the “Board”) of CoStar Group, Inc. (“CoStar,” “CoStar Group,” “we,” “our,” “us,” or the “Company”) solicits your proxy for use at the Annual Meeting of Stockholders (the “Annual Meeting”) to be held at 10:00 a.m., Eastern Time, on Thursday, June 26, 2025, and at any adjournment or postponement of the Annual Meeting. The Annual Meeting will be held online only as a live webcast via the internet at www.virtualshareholdermeeting.com/CSGP2025. The webcast replay of the Annual Meeting will be made available in the Investor section of CoStar Group’s website after completion of the Annual Meeting and will remain available for a period of time following the call.

We are mailing the Notice of Internet Availability of Proxy Materials (the “Notice”) to our stockholders eligible to vote at the Annual Meeting on or about April 30, 2025. If you are a registered stockholder, to be admitted to the Annual Meeting, you will need to enter the 16-digit control number found on your Notice or proxy card. If your shares are held in brokerage accounts and your voting instruction form or the Notice indicates that you may vote those shares through the www.proxyvote.com website, then you may be admitted to the Annual Meeting using the 16-digit control number indicated on that voting instruction form or the Notice. Otherwise, stockholders who hold their shares in brokerage accounts should contact their bank, broker or other nominee (preferably at least five days before the Annual Meeting) and obtain a “legal proxy” in order to be able to attend, participate in or vote at the Annual Meeting. Only stockholders as of the record date or their proxies are permitted to attend the Annual Meeting online.

The Annual Meeting will include a question and answer session, and stockholders may submit questions appropriate to our business during the Annual Meeting. Questions may be submitted during the Annual Meeting through www.virtualshareholdermeeting.com/CSGP2025. Questions pertinent to meeting matters that comply with the meeting rules of conduct will be answered during the question and answer session, subject to time constraints. However, we reserve the right to exclude questions that are not pertinent to meeting matters, irrelevant to the business of the Company, derogatory or in bad taste, or relate to pending or threatened litigation, personal grievances or are otherwise inappropriate. Questions that are substantially similar may be grouped and answered once to avoid repetition. If there are any questions pertinent to meeting matters that cannot be answered during the meeting due to time constraints, management expects to post answers to those questions on the “Investor Relations” section of the Company’s website at investors.costargroup.com as soon as practicable after the meeting.

We encourage you to access the Annual Meeting 15 minutes before it begins to avoid any delay from technical issues. If you encounter technical issues accessing the virtual Annual Meeting, you can contact the technical support number posted on the login page at www.virtualshareholdermeeting.com/CSGP2025.

Proposal 1

ELECTION OF DIRECTORS

At the recommendation of the Nominating and Corporate Governance Committee, the Board has nominated all eight of the current directors for reelection, all of whom were last elected at the 2024 Annual Meeting of Stockholders, except for Mr. Berisford, Ms. Glaser, and Ms. McCarthy who were appointed to the Board in April 2025. Ms. Glaser was recommended to the Company by a third-party search firm, and Mr. Berisford and Ms. McCarthy were recommended to the Company by security holders, as detailed in applicable support agreements with such security holders.

Each director elected at the Annual Meeting will serve until the next Annual Meeting of Stockholders or until his or her successor is elected and qualified. We know of no reason why any nominee would be unable to serve. If any nominee becomes unable to serve prior to the Annual Meeting, the Board may reduce the size of the Board or designate substitute nominees, and proxies that do not withhold authority to vote for directors will be voted for such substitute nominees. In no event may proxies be voted for a greater number of persons than the number of nominees named. We did not receive any stockholder nominations for directors in connection with the Annual Meeting.

		THE BOARD UNANIMOUSLY RECOMMENDS A VOTE FOR EACH OF THE DIRECTOR NOMINEES

Board Composition

Our Nominating and Corporate Governance Committee reviews and assesses with the Board the Board’s membership criteria. These criteria include independence, judgment, integrity, ability to commit sufficient time and attention to the activities of the Board, absence of potential conflicts with the Company’s interests, business experience, skills and background, including an understanding of and experience with real estate, information services and technology industries, and finance and marketing expertise.

In addition, the Nominating and Corporate Governance Committee evaluates the composition of the Board to assess the skills and experience that are currently represented on the Board, as well as the skills and experience that the Nominating and Corporate Governance Committee believes the Board will find valuable in the future, given the Company’s current standing and strategic plans. This evaluation enables the Nominating and Corporate Governance Committee to assess its effectiveness at achieving these Board membership objectives.

We expect that our Board members will have a varied portfolio of skills, experiences and backgrounds and that each will contribute to the composition of the Board so that, collectively, the Board will possess the necessary skills, experience and background to oversee our business and affairs in light of the Company’s current standing and strategic plans. Below is a list of key skills and experience that our directors bring to our Board that we consider important in light of our current business and structure.

DIRECTOR SKILLS/EXPERIENCE

Industry I Commercial Real Estate: Experience in the real estate, information services and technology industries areas is valuable in understanding our growth and development efforts, as well as the market segments in which we operate.

Public Company Governance: Experience with reporting obligations, investor interaction, public company governance, knowledge and understanding of governance planning, and experience in encouraging management accountability and protecting stockholder interests.

Global Business: Broad exposure to companies or organizations that have a significant global presence, including developing and managing business in markets around the world.

Financial Accounting and Reporting: Experience in accounting or financial reporting, including understanding of internal controls; experience in overseeing such reporting and controls.

Legal, Public Policy, and Regulatory: Expertise in compliance with applicable governmental regulations; experience in legal and regulatory matters, and corporate compliance and ethics policies; experience in managing the effects of government policies and regulations.

Business Development and M&A: Expertise in and understanding of business development, strategic planning, and implementation; experience in leading strategy discussion at the board level; experience with developing and implementing strategies for growth, including mergers and acquisitions and divestitures.

Talent Management and Executive Compensation: Broad experience in executive development, performance, and compensation; experience with HR processes and strategies and efforts to attract, motivate, and retain candidates for key positions; experience in talent development.

Marketing and Sales: Experience with enhancing sales in existing markets; experience in developing new products and services and markets for growth; experience in marketing communication, brand strategy development, and advertising.

Risk Management: Experience in the management of critical business and/or legal risk; understanding of risk management functions, including risk identification/classification, crisis management and similar functions; ability to think strategically about risk and provide oversight and advice relating to risk.

Senior Management and Leadership: Experience as chief executive officer, president, chairman, or at similar leadership position in a large company or other large organization.

Cybersecurity and Data Privacy: Experience in overseeing and managing cybersecurity and data privacy risks; history of leadership roles in cybersecurity risk management; degrees, certifications, or other background in cybersecurity.

Corporate Responsibility and Sustainability: Experience in overseeing and managing Corporate Responsibility practices and initiatives; skills and knowledge in climate-related strategic planning, risk mitigation, and management; ability to provide oversight and advice relating to climate-related risks.

 VERY SKILLED/EXPERIENCED       SOME SKILL/EXPERIENCE

Board Evaluation Process

The Nominating and Corporate Governance Committee identifies nominees for director, and considers recommendations from other members of the Board, officers and employees of CoStar and other sources that the Nominating and Corporate Governance Committee deems appropriate, which may include professional search firms. The Nominating and Corporate Governance Committee will also consider Board nominees suggested by stockholders if such recommendations are submitted timely, and include the required information specified in our By-Laws, as described under “Stockholder Proposals and Nominations for Directors for the 2026 Annual Meeting of Stockholders” below.

The Company may require any proposed nominee to furnish other information as reasonably required to determine eligibility to serve as a director of the Company, including information regarding the proposed nominee’s independence. There is no difference in the manner by which the Nominating and Corporate Governance Committee evaluates prospective nominees for director based on the source from which the individual was first identified.

When evaluating nominees for director, the Nominating and Corporate Governance Committee considers, among other things, an individual’s business experience and skills, background, independence, judgment, integrity and ability to commit sufficient time and attention to the activities of the Board, as well as the absence of any potential conflicts with the Company’s interests. If the nominee is a director standing for reelection, that individual’s past contribution, engagement and commitment to CoStar are also considered. The Nominating and Corporate Governance Committee evaluates the totality of the merits of each prospective nominee that it considers and does not establish minimum qualifications or attributes. Candidates are evaluated within the context of the perceived needs of the Board as a whole, so that the members of the Board, collectively, will possess the necessary skills, experience and background.

John Berisford, Rachel Glaser, and Christine McCarthy, appointed in 2025, were identified through a rigorous director search process led by a special committee of the Board, leveraging an external search firm. The process included an extensive evaluation of candidates against key criteria such as industry expertise, technological acumen and leadership experience. The special committee conducted multiple rounds of review, interviews and deliberations to ensure that the selected directors would complement the Board’s existing strengths.

Director Nominees

Board Leadership Structure

Currently, Ms. Sams, an independent director, serves as Board Chair, and Mr. Florance serves as Chief Executive Officer and director of CoStar Group. The Board does not have a policy regarding the separation of the roles of Chief Executive Officer and Board Chair, as the Board believes it is in the best interests of the Company to make that determination based on the position and direction of the Company and the membership of the Board at the particular time. The Board believes the advisability of having separate or combined Board Chair and Chief Executive Officer positions is dependent upon the strengths of the individual or individuals that hold these positions and the most effective means of leveraging their strengths to lead the Board, set Board agendas, and identify and oversee key issues in light of the challenges and circumstances facing the Company, which may change over time. During a period in which the Board Chair and Chief Executive Officer positions are combined, a Lead Director would be appointed from our independent directors. Our stockholders would be notified of a combination of the Board Chair and Chief Executive Officer roles promptly upon the Board’s decision to do so.

The Board has determined that the Company’s current leadership structure is in the best interest of the Company’s stockholders. This structure provides a greater role for the independent directors in overseeing the Company and in setting agendas and establishing Board priorities and procedures and it also permits our Chief Executive Officer to focus on managing the Company’s day-to-day operations. Our Board Chair’s responsibilities include:

The Board’s Role in Risk Oversight

One of the Board’s functions is oversight of risk management, which is administered both through the full Board and through Board committees that oversee specific risks, as described below.

The Company faces a variety of risks, including macroeconomic risks, such as inflation, economic downturns, or recession; business-specific risks related to the Company’s strategic position, operations, financial structure, legal and regulatory compliance, cybersecurity and corporate governance; and event-specific risks, such as natural disasters, pandemics or wars. The Company believes that an effective risk management system should:

The Company has developed a robust information security risk management infrastructure that leverages our internal Threat Management and Privacy teams and external third-party assessors to continuously refine protocols for cybersecurity and information security risks. Our internal teams utilize a third-party information security risk management process to

evaluate cybersecurity impact of proposed software prior to adoption, performing privacy impact assessments as applicable. As of the date of this filing, the Company is not aware of and has not experienced any third-party information security breaches. In addition to our internal teams’ capabilities, we engage a third-party managed detection and response provider and an external data protection officer, to which our Threat Management team gives regular reports to for monitoring.

The Board encourages management to promote a corporate culture that incorporates risk management into the Company’s corporate strategy and day-to-day operations. Management is responsible for identifying risk and risk controls related to significant business activities and developing programs and recommendations to determine the sufficiency of risk identification, the balance of potential risk to potential reward, and the appropriate manner in which to control risk.

Management, typically the Chief Financial Officer or General Counsel, periodically discusses with the Board or appropriate Board committee the significant voluntary and involuntary risks that the Company faces and how the Company is seeking to control risk if and when appropriate. When appropriate, other members of management provide information to the Board or appropriate Board committees with respect to a specific area of potential risk and how the Company manages or seeks to control the identified risk. The Audit Committee oversees management’s implementation of our cybersecurity risk management program and is informed about the Company’s cybersecurity risks program in periodic presentations by our Chief Technology Officer, including an overview of cybersecurity risks and the threats landscape as well as the Company’s risk posture.

In some cases, as with risks related to product or service acceptance, risk oversight is addressed as part of the full Board’s engagement with the Chief Executive Officer and management. In other cases, a Board committee is responsible for oversight of specific risk topics, in which case management meets directly with the Board committee. For example, the Audit Committee oversees issues related to internal control over financial reporting and auditor independence, and the Compensation Committee oversees the assessment of risks related to the Company’s compensation policies and programs applicable to officers and employees, as discussed in greater detail below. Additionally, the Company’s management engages directly with Board committees to facilitate Board oversight in certain matters. For example, the Company’s management reports on the Company’s political contributions to the Nominating and Corporate Governance Committee. The Board also works with the Company’s management to assess, analyze and address the most likely areas of future risk for the Company. The Company has released voluntary reports covering its approach to building a foundation of responsible business strategies that drive value for its people, communities, and stockholders. The Company’s management anticipates regularly reviewing its voluntary reporting on such matters and providing periodic updates to the Board.

Risk Assessment in Compensation Programs

Management assesses the Company’s executive and broad-based compensation and benefits programs to determine if the programs’ provisions and operations encourage or create undesired or unintentional risk of a material nature. The Compensation Committee also engaged its independent compensation consultant (Willis Towers Watson) to assess the Company’s executive compensation program. The risk assessment evaluated potential risk factors from three primary perspectives:

The Compensation Committee reviews all compensation programs but is focused on the programs with variability of payout, with the ability of a participant to directly affect payout and the controls on participant action and payout. The Company supports the use of base salary, performance-based compensation and retirement plans that are generally uniform in design and operation throughout the Company. In most cases, the compensation policies and practices are centrally designed and administered and are substantially identical throughout the Company, except that sales personnel are also eligible to receive sales commissions depending upon performance. Programs may differ by country due to variations in local laws and customs.

Based on the foregoing, we believe that our compensation policies and practices do not create risks that are reasonably likely to have a material adverse effect on the Company. We also believe that our incentive compensation arrangements provide incentives that do not encourage risk-taking beyond our ability to effectively identify and manage significant risks, are compatible with effective internal controls and our risk management practices, and are supported by the Compensation Committee’s oversight and administration of executive compensation programs.

Board Committees

Corporate Governance Overview

Principles of Corporate Governance

The Board, based on the recommendation of the Nominating and Corporate Governance Committee, adopted the Company’s Principles of Corporate Governance, which direct our Board’s actions with respect to, among other things, Board composition, director membership criteria, composition of the Board’s standing committees, and the Board’s performance evaluations. When identifying, screening, recruiting and recommending candidates to the Board, the Nominating and Corporate Governance Committee aims to include in each search (whether conducted in-house or with the assistance of a third-party search firm) qualified candidates who reflect a variety of backgrounds.

In April 2025, the Board amended the Principles of Corporate Governance to adopt a retirement policy providing that no director will be nominated for election or re-election to the Board if he or she would be 75 or older at the time of the election, unless the Nominating & Corporate Governance Committee and Board determine that the continued service of the director on the Board would be of benefit to the Company. The Company’s Principles of Corporate Governance can be found in the “Investors” section of the Company’s website under Corporate Governance – Governance Documents.

Majority Voting Standard

In a non-contested election, directors are elected by a majority of votes cast by stockholders (i.e., if the number of votes cast for the nominee’s election exceeds the number of votes cast against the nominee’s election). A non-contested election is an election where the number of nominees does not exceed the number of directors to be elected. In a contested election, the director nominees who receive the plurality of votes cast are elected as directors. Under the plurality standard, the number of persons equal to the number of vacancies to be filled who receive more votes than other nominees are elected to the Board, regardless of whether they receive a majority of votes cast. An election is considered contested under our By-Laws if there are more nominees than positions on the Board to be filled at the meeting of stockholders as of the fifth business day prior to the date on which we file our definitive proxy statement with the SEC.

Meeting Attendance

Directors are expected to attend all meetings of the Board and the committees on which they serve. During 2024, the Board held seven meetings. In 2024, the Audit, Compensation, and Nominating and Corporate Governance Committees held four meetings, one meeting and five actions by written consent, and one meeting, respectively. During 2024, each director attended at least 75% of the aggregate of the total number of meetings of the Board and the total number of meetings held by each committee of the Board on which the director served, during the period in which the director so served.

We encourage, but do not require, directors to attend the Annual Meetings of Stockholders. In 2024, one director attended the Annual Meeting of Stockholders.

Executive Sessions

Executive sessions of independent directors enable the Board to discuss matters, such as strategy, Chief Executive Officer and senior management performance and compensation, and board effectiveness, without management present. Any director may request additional executive sessions of independent directors.

Proxy Access

Our By-Laws allow eligible stockholders to propose director nominees for inclusion in the proxy statement in addition to the nominees proposed by the Board. The proxy access By-Law permits stockholders owning 3% or more of our issued and outstanding shares of common stock for at least three years, to nominate candidates for election to our Board. The number of candidates that may be so nominated is limited to the greater of two or the largest whole number that does not exceed 20% of our Board. The number of stockholders who may aggregate their shares to meet the 3% ownership threshold is limited to 20. The stockholder(s) and nominee(s) must also satisfy the other requirements contained in our By-Laws.

Director Independence

The Board has determined that Messrs. Berisford, Hill, and Musslewhite, and Mses. Brunner, Glaser, McCarthy, and Sams are each independent as defined under Rule 5605(a)(2) of the Nasdaq listing rules. The Board also determined that Messrs. Klein and Nassetta and Ms. Kaplan, former directors, were each independent as defined under Rule 5605(a)(2) of the Nasdaq listing rules during their Board service. In assessing directors’ independence, the Board took into account certain transactions, relationships, and arrangements involving some of the directors and concluded that such transactions, relationships, and arrangements did not impair the independence of the relevant director. As part of this determination, the Board received information regarding Mr. Klein’s position as a trustee of the Shakespeare Theatre Company, a non-profit organization, and Mr. Hill’s position as an emeritus trustee of the Shakespeare Theatre Company. The Company made contributions to the Shakespeare Theatre Company of $50,000 in 2022, $50,000 in 2023, and $50,000 in 2024, which amounts are less than five percent of the consolidated gross annual revenues of the Shakespeare Theatre Company for those years. The Board also noted Mr. Hill’s position as director on the board of Step Afrika!, a non-profit organization. The Company made contributions to Step Afrika! of $7,500 in 2022 and $25,000 in 2024, which amounts are less than five percent of the consolidated gross annual revenues of Step Afrika! for those years. In addition, the Board considered that Mr. Nassetta serves as an executive officer of a company that subscribes to the Company’s services and from which the Company purchased services, and Ms. Brunner serves as Chief Executive Officer of a company that subscribes to the Company’s services. In each such case, the payments received by the Company were less than one percent of the Company’s consolidated gross annual revenues in each of the last three fiscal years. In addition, the payments from the Company to Mr. Nassetta’s company were less than one percent of the consolidated gross annual revenues of such company in each of the last three fiscal years. Further, the services provided by the Company to and received from the companies Mr. Nassetta and Ms. Brunner are affiliated with are on terms no less favorable than terms generally available to an unaffiliated third party under the same or similar circumstances.

Stockholder Communications with the Board

Stockholders may communicate with our Board by sending written correspondence to CoStar Group, Inc., Attention: Corporate Secretary, 1201 Wilson Blvd., Arlington, Virginia 22209. The Corporate Secretary opens and retains a copy of the contents of such correspondence and promptly forwards such correspondence to the Chair of the Nominating and Corporate Governance Committee and, if addressed to a particular committee or Board member, to that committee’s Chair or such Board member. The Corporate Secretary, together with the Chair of the Nominating and Corporate Governance Committee and his duly authorized agents, are responsible for collecting and organizing stockholder

communications. Absent a conflict of interest, the Chair of the Nominating and Corporate Governance Committee is responsible for evaluating the materiality of each stockholder communication and determining which stockholder communications will be presented to the full Board, individual directors or other appropriate body.

Director Compensation

The Compensation Committee annually reviews director compensation for service on the Board and its committees and recommends director compensation and any changes to such compensation to the Board for approval. The Board annually reviews and approves director compensation based on the recommendations of the Compensation Committee. Directors who are also employees of the Company do not receive any additional compensation for service on the Board. The charts below show for 2024 the percentage of our Board Chair’s and all other directors’ compensation that is paid in stock as compared to cash to align their interests with those of our stockholders, and the following table shows the compensation we paid in 2024 to our non-employee directors who served the full year.

2024 Non-Employee Director Compensation

Director Stock Ownership Policy

Under the Company’s Director Stock Ownership Policy, each non-employee director is required to own shares of the Company’s common stock with a value equal to five times the annual, standard director cash retainer. Newly appointed directors are required to meet the ownership requirement on or before the first December 31st following the fifth anniversary of the date of their appointment to the Board. The current directors are all in compliance with our Director Stock Ownership Policy.

The number of shares of unvested restricted stock held by each non-employee director as of December 31, 2024, is shown above by footnote to the 2024 Director Compensation table.

Certain Relationships and Related Party Transactions

Review and Approval of Related Party Transactions

The Board recognizes that Related Party (as defined below) transactions can present potential or actual conflicts of interest and create the appearance that Company decisions are based on considerations other than the best interests of the Company and its stockholders. The Board has delegated authority to the Audit Committee to review and approve Related Party transactions, and the Audit Committee has adopted a written policy as detailed below, for the review, approval, or ratification of Related Party transactions.

A Related Party transaction, otherwise known as an “Interested Transaction” under our policy, is any transaction, arrangement or relationship (including any indebtedness or guarantee of indebtedness), or any series of similar transactions, arrangements or relationships, in which (a) the aggregate amount involved will or may be expected to exceed $120,000 in any calendar year, (b) the Company or any of its subsidiaries is a participant, and (c) any Related Party has or

will have a direct or indirect interest (other than solely as a result of being a director or a less than 10% beneficial owner of another entity). An Interested Transaction does not include a transaction in which a Related Party has an indirect interest solely as a result of being (1) a director or a less than 10% beneficial owner of an equity interest in another entity, or both, or (2) a limited partner in a partnership in which the Related Party has an interest of less than 10%. A “Related Party” is any (a) person who is or was (since the beginning of the Company’s last fiscal year, even if they do not presently serve in that role) an executive officer, director or nominee for election as a director of the Company, (b) greater than 5% beneficial owner of the Company’s outstanding common stock, or (c) Immediate Family Member of any of the foregoing. An “Immediate Family Member” includes a person’s spouse, parents, stepparents, children, stepchildren, siblings, mothers- and fathers-in-law, sons and daughters-in-law, brothers- and sisters-in-law and anyone residing in such person’s home (other than a tenant or employee).

The Audit Committee will review all of the material facts of all Interested Transactions and either approve or disapprove of the entry into the Interested Transaction, subject to a limited list of enumerated transactions that are deemed to be pre-approved as described in the Interested Transactions policy. In determining whether to approve an Interested Transaction, the Audit Committee will take into account, among other factors it deems appropriate, whether the Interested Transaction is on terms no less favorable than terms generally available to an unaffiliated third party under the same or similar circumstances and the extent of the Related Party’s interest in the transaction.

Related Party Transactions

During 2024, no Related Party transaction (or “Interested Transaction”) occurred between the Company and any Related Party.

Executive Officers

Below is biographical information about each of our current executive officers as defined by the Exchange Act, including ages as of April 1, 2025.

Proposal 2

RATIFICATION OF THE APPOINTMENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

The Audit Committee approved the appointment of Ernst & Young LLP as the Company’s independent registered public accounting firm for 2025. As a matter of good corporate governance, the Board is asking stockholders to ratify this appointment. If stockholders do not ratify this appointment, the Audit Committee may reconsider such appointment and consider other accounting firms.

Ernst & Young LLP has served as the independent registered public accounting firm for the Company, its subsidiaries, and its predecessors since 1994. A representative from Ernst & Young LLP is expected to attend the Annual Meeting, and will have the opportunity to make a statement and to respond to appropriate questions.

		THE BOARD UNANIMOUSLY RECOMMENDS A VOTE FOR RATIFICATION OF THE APPOINTMENT OF ERNST & YOUNG LLP AS THE COMPANY’S INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM FOR 2025

Ernst & Young LLP Fees and Services

For the years ended December 31, 2023 and 2024, Ernst & Young LLP billed CoStar the fees set forth below, including expenses, in connection with services rendered to CoStar:

Audit Committee Pre-Approval Policy

The Audit Committee’s policy is that all audit and non-audit services provided by CoStar’s independent registered public accounting firm shall either be approved before the independent registered public accounting firm is engaged for the

particular services or shall be rendered pursuant to pre-approval procedures established by the Audit Committee. These services may include audit services and permissible audit-related services, tax services and other services. Pre-approval spending limits for services to be performed by CoStar’s independent registered public accounting firm are established on an annual (for audit services) or periodic (for permissible non-audit services) basis, detailed as to a particular service or category of services to be performed. Any audit or non-audit service fees that may be incurred by CoStar that fall outside the pre-approved limits must be reviewed and approved by the Chair of the Audit Committee or the Audit Committee as a whole prior to the performance of services. CoStar’s independent registered public accounting firm reports to the Audit Committee on a quarterly basis on all services rendered by the independent registered public accounting firm that were pre-approved and all fees paid to the independent registered public accounting firm for such services since the previous quarter’s Audit Committee meeting. The Audit Committee may revise its pre-approval spending limits and policies at any time.

All fees paid to the independent registered public accounting firm in 2024 were pre-approved by the Audit Committee, and therefore no services were approved after the services were rendered pursuant to the “de minimis” exception established by the SEC for the provision of non-audit services.

Report of the Audit Committee

The Audit Committee oversees the Company’s financial reporting process on behalf of the Board. Management has the primary responsibility for the financial statements and the reporting process. The Company’s independent registered public accounting firm is responsible for expressing an opinion on the conformity of the Company’s audited consolidated financial statements to GAAP.

In this context, the Audit Committee has:

In reliance on the reviews and discussions referred to above, the Audit Committee recommended to the Board that the audited consolidated financial statements be included in the 2024 Annual Report for filing with the SEC.

By the Audit Committee

of the Board of Directors

John W. Hill, Chair

Angelique G. Brunner

Louise S. Sams

Proposal 3

ADVISORY RESOLUTION TO APPROVE EXECUTIVE COMPENSATION

(SAY-ON-PAY)

In accordance with the Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010 (the “Dodd-Frank Act”) and Rule 14a-21 under the Exchange Act, we request that our stockholders cast a non-binding, advisory vote to approve the compensation of our NEOs identified in the section titled “Compensation Discussion and Analysis” set forth below in this Proxy Statement. This proposal, commonly known as a “say-on-pay” proposal, gives our stockholders the opportunity to express their views on our NEOs’ compensation. This vote is not intended to address any specific item of compensation, but rather the overall compensation of our NEOs and the philosophy, policies and practices described in this Proxy Statement.

We urge stockholders to read the “Compensation Discussion and Analysis” section of this Proxy Statement, which describes in detail how our executive compensation policies and procedures operate and are designed to achieve our compensation objectives, as well as the 2024 Summary Compensation Table and other related compensation tables and narrative accompanying the “Compensation Discussion and Analysis” in this Proxy Statement, which provide detailed information on the compensation of our NEOs. The Compensation Committee and the Board of Directors believe that the policies and procedures articulated in the “Compensation Discussion and Analysis” are effective in achieving our goals and that the compensation of our NEOs reported in this Proxy Statement has supported and contributed to the Company’s recent and long-term success.

We are asking stockholders to approve the following advisory resolution at the Annual Meeting:

RESOLVED, that the stockholders of CoStar Group, Inc. approve, on a non-binding, advisory basis, the compensation paid to the Company’s named executive officers, as disclosed pursuant to Item 402 of Regulation S-K, including the Compensation Discussion and Analysis, the 2024 Summary Compensation Table and the related compensation tables, notes and narrative in the Proxy Statement for the Company’s 2025 Annual Meeting of Stockholders.

This advisory resolution is non-binding on the Board and the Compensation Committee. Although non-binding, the Board and the Compensation Committee will review and consider the voting results when making future decisions regarding our executive compensation program. At the 2024 Annual Meeting, approximately 92% of the votes cast were for approval of the “say-on-pay” advisory vote.

At our annual meeting of stockholders held on June 8, 2023, our stockholders selected “1 Year” as the recommended frequency for future “say-on-pay” advisory votes. As a result, we expect to continue to submit our say-on-pay proposal to our stockholders at each annual meeting.

		THE BOARD UNANIMOUSLY RECOMMENDS A VOTE FOR THE APPROVAL OF THE ADVISORY RESOLUTION TO APPROVE EXECUTIVE COMPENSATION

COMPENSATION DISCUSSION AND ANALYSIS

Our Compensation Discussion and Analysis describes our executive compensation programs and compensation decisions for our NEOs for 2024. Our Compensation Committee is responsible for reviewing our executive compensation program and for reviewing and approving the compensation arrangements for our NEOs. Our NEOs for 2024 were:

Executive Compensation Program Objectives

Our Compensation Committee is responsible for designing and maintaining the Company’s executive compensation program consistent with the objectives below. The Company’s executive compensation program seeks to:

Executive Compensation Policies and Practices

Below we highlight certain key characteristics of our executive compensation practices that we believe align executive compensation with stockholder interests and promote good governance.

		Purpose				Compensation Program/Policy