UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

For the fiscal year ended December 31, 2025

OR

For the transition period from ______ to ______

Commission file number 0-24531

CoStar Group, Inc.

(Exact name of registrant as specified in its charter)

(Address of principal executive offices) (zip code)

(202) 346-6500

(Registrant’s telephone number, including area code)

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

Securities registered pursuant to section 12(g) of the Act: None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes x No o

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes o No x

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports) and (2) has been subject to such filing requirements for the past 90 days. Yes x No o

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes x No o

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and "emerging growth company" in Rule 12b-2 of the Exchange Act.

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. o

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. x

If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements. o

Indicate by checkmark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant's executive officers during the relevant recovery period pursuant to §240.10D-1(b). o

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act). Yes ☐ No x

As of June 30, 2025, the aggregate market value of the common stock (based upon the closing price of the stock on the Nasdaq Global Select Market) of the registrant held by non-affiliates was approximately $33.9 billion. As of February 20, 2026, 419,793,301 shares of common stock were outstanding.

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the registrant’s definitive proxy statement, which is expected to be filed with the Securities and Exchange Commission within 120 days after the end of the registrant’s fiscal year ended December 31, 2025 are incorporated by reference into Part III of this Report.

TABLE OF CONTENTS

Glossary of Terms

The following abbreviations or acronyms used in this Annual Report on Form 10-K (this "Report") are defined below:

Cautionary Statement Concerning Forward-Looking Statements

We have made forward-looking statements in this Report and make forward-looking statements in our other reports filed with the SEC, press releases, and conference calls that are subject to risks and uncertainties. Forward-looking statements include information that is not purely historic fact. Sections of this Report that contain forward-looking statements include “Business,” “Risk Factors,” “Properties,” “Legal Proceedings,” “Management’s Discussion and Analysis of Financial Condition and Results of Operations,” “Quantitative and Qualitative Disclosures About Market Risk,” “Controls and Procedures,” and the Consolidated Financial Statements and related Notes.

Our forward-looking statements are also identified by words such as “hope,” “anticipate,” “may,” “likely,” “might,” “believe,” “expect,” “observe,” “consider,” “think,” “intend,” “envision,” “will,” “should,” “could,” “would,” “plan,” “target,” “estimate,” “predict,” “continue,” “commit,” and “potential” or the negative of these terms or other comparable terminology. You should understand that these forward-looking statements are estimates reflecting our judgment, beliefs, and expectations, not guarantees of future performance. They are subject to a number of assumptions, risks, and uncertainties that could cause actual results to differ materially from those expressed or implied in the forward-looking statements. The following important factors, in addition to those discussed or referred to under the heading “Risk Factors,” and other unforeseen events or circumstances, could affect our future results and could cause those results or other outcomes to differ materially from those expressed or implied in our forward-looking statements:

• the risks related to AI Technologies, such as Homes AI;

• our inability to attract and retain new clients;

• our inability to successfully develop and introduce new or updated online marketplace services, information, and analytics;

• our inability to compete successfully against existing or future competitors in attracting advertisers and in general;

• the effects of fluctuations and market cyclicality;

• the effects of global economic uncertainties and downturns or a downturn or consolidation in the real estate industry;

• our inability to hire qualified persons for, or retain and continue to develop, our sales force, or unproductivity of our sales force;

• our inability to retain and attract highly capable management and operating personnel;

• the downward pressure that our internal and external investments may place on our operating margins;

• our inability to increase brand awareness;

• our inability to maintain or increase internet traffic to our marketplaces, and the risk that the methods, including Google Analytics, that we use to measure average monthly unique visitors to our portals may misstate the actual number of unique persons who visit our network of mobile applications and websites for a given month or may differ from the methods used by competitors;

• our inability to attract new advertisers;

• our inability to successfully identify, finance, integrate, and/or manage costs related to acquisitions;

• our inability to complete certain strategic transactions if a proposed transaction is subject to review or approval by regulatory authorities pursuant to applicable laws or regulations;

• our inability to realize the benefits of the Matterport Acquisition or the Domain Acquisition;

• the inability of third-party suppliers upon which Matterport relies to fulfill its needs;

• the effects of cyberattacks and security vulnerabilities, and technical problems or disruptions;

• the significant costs associated with undertaking a large infrastructure project;

• our inability to generate increased revenue from our current or future geographic expansion plans;

• the risks related to acceptance of credit cards and debit cards and facilitation of other customer payments;

• the effects of climate-related events and other events beyond our control;

• the effects related to attention to climate-related risk and opportunities;

• our inability to obtain and maintain accurate, comprehensive, or reliable data;

• our inability to obtain and maintain stable data feeds, or disruption of our data feeds;

• our inability to enforce or defend our ownership and use of intellectual property;

• the effects of use of new and evolving technologies, including AI, on our ability to protect our data and intellectual property from misappropriation by third parties;

• our inability to defend against potential legal liability for collecting, displaying, or distributing information;

• our inability to obtain or retain listings from real estate brokers, agents, property owners, and apartment property managers;

• our inability to maintain or establish relationships with third-party listing providers;

• our inability to comply with the rules and compliance requirements of MLSs;

• the risks related to open source software;

• the risks related to international operations;

• the effects of foreign currency exchange rate fluctuations;

• our indebtedness;

• the effects of a lowering or withdrawal of the ratings assigned to our debt securities by rating agencies;

• the effects of any actual or perceived failure to comply with privacy or data protection laws, regulations, or standards;

• the effects of changes in tax laws, regulations, or fiscal and tax policies;

• the effects of third-party claims, litigation, regulatory proceedings, or government investigations; and

• the risks related to return on investment; and

• the risks related to the specific timing, price, and size of repurchases under the Stock Repurchase Program, including that the Stock Repurchase Program may be suspended or discontinued at any time at the Company’s discretion.

Accordingly, you should not place undue reliance on forward-looking statements, which speak only as of, and are based on information available to us on, the date of this Report. All subsequent written and oral forward-looking statements attributable to us or any person acting on our behalf are expressly qualified in their entirety by the cautionary statements contained or referred to in this section. We do not undertake any obligation to update any such statements or release publicly any revisions to these forward-looking statements to reflect new information or events or circumstances after the date of this Report or to reflect the occurrence of unanticipated events, except as required by applicable law. Additionally, certain information disclosed herein or elsewhere (such as our website) is informed by various stakeholder expectations and third-party frameworks. Such information is not necessarily material for purposes of our SEC reporting, even if we use “material” or similar language. Particularly, with respect to climate-related risks and opportunities materiality is subject to various definitions that differ from, and are often more expansive than, the definition under U.S. federal securities laws.

PART I

In this Report, the words “we,” “our,” “us,” “CoStar Group,” or the “Company” refer to CoStar Group, Inc. and its direct and indirect wholly-owned subsidiaries. This Report also refers to our websites, but information contained on those sites is not part of this Report.

Overview

CoStar Group is a leading provider of online real estate marketplaces, information, analytics, and 3D digital twin technology in the property markets. Our mission is to digitize the world's real estate, empowering all people to discover properties, insights, and connections that improve their businesses and lives.

We own and operate leading online marketplaces for real estate in the U.S., Australia, Europe, Canada, and Asia-Pacific based on the numbers of unique visitors and site visits per month. We provide more information, analytics, and marketing services than many of our competitors; offer the most comprehensive commercial real estate database available; and have the largest commercial real estate research department in the industry. We have created and compiled a standardized platform of online marketplace services, information, and analytics where industry professionals, consumers of real estate, and the related business communities can continuously interact and facilitate transactions by efficiently accessing and exchanging accurate and standardized real estate-related information.

Strategy

Our strategy is to provide real estate industry professionals and consumers with critical knowledge to explore and complete transactions by offering the most comprehensive, timely, and standardized information on real estate, and the right tools to be able to effectively utilize that information. Over time, we have expanded and continue to expand our services for real estate online marketplaces, information, analytics, and 3D digital twin technology to address the evolving needs of the industry as it grows and evolves.

Our standardized platform includes the most comprehensive proprietary database of commercial real estate information in the industry; the largest research department in the commercial real estate industry; proprietary data collection, information management, and quality control systems; a large in-house product development team; a broad suite of web-based information, analytics, and online marketplace services; a large team of analysts and economists; risk management tools; 3D digital twin technology in the property markets; and a large, diverse base of clients.

We have spent more than 35 years building and acquiring databases of real estate information, which includes information on homes, schools, communities, commercial properties, leasing, sales, comparable sales, tenants, and demand statistics, as well as digital images, drone videos, and 3D tours, plot maps, and floor plans. This highly complex database is comprised of

hundreds of data fields, tracking such categories as location, site and zoning information, building characteristics, space and unit characteristics and availability, tax assessments, true ownership, sales and lease comparables, residential rents, vacancies and concessions, space requirements, retail locations, mortgage and deed information, for-sale and for-lease listings, fund data, income and expense histories, tenant names, tenant credit scores, view of company locations, lease expirations, contact information, historical trends, forecasts, and demographic information. In addition to our internal efforts to grow the database, we have obtained and assimilated a number of proprietary databases. Our comprehensive commercial real estate database powers our information services, sources data used in our analytic services, and provides content for most of our online marketplace services and our auction platform. Our ability to utilize the same commercial real estate information across our standardized platform creates efficiencies in operations and improves data quality for our customers.

We deliver our comprehensive commercial real estate information content to our customers primarily via an integrated solution of online service offerings that includes information about space available for-lease, comparable sales information, information about properties for-sale, tenant information, internet marketing services, risk management tools, analytical capabilities, information for clients’ websites, information about industry professionals and their business relationships, data integration, and industry news. We also operate complementary online marketplaces for commercial and residential real estate listings, apartment rentals, land for sale, and business for sale, as well as a commercial real estate auction platform. We have developed and we expect to continue to develop additional services leveraging our centralized database and 3D digital twin technology to meet the needs of our existing customers as well as potential new categories of customers. We also continue to leverage AI by deeply integrating it into our products and internal processes. AI is driving research efficiencies, improving data quality and increasing the pace of product development. We strive to cross-sell our services to our customers to best suit their needs.

CoStar Research

Research Department. Our research professionals undergo an extensive training program so that we can maintain consistent research methods and processes throughout our research department. Our researchers collect and analyze commercial real estate information through phone calls, e-mails, and additional research methods including field inspections, public records review, news monitoring, third-party data feeds, and user entered content. We also use advanced technology, including AI, to improve how we collect and validate data and enhance the capabilities and insights we deliver to clients. We have also set up direct feeds from larger apartment sites, owners, brokers, and home builders.

Our researchers are responsible for maintaining the accuracy and reliability of our database information, training our clients to use CoStar Group products, and handling their customer service questions, creating a "one-touch" approach to customer care. Because of the importance commercial real estate professionals place on our data and our prominent position in the industry, many of these professionals routinely take the initiative and proactively report available space and transactions through our online tool, which we refer to as our Marketing Center, or directly to our researchers.

Our field research efforts include physical inspections of properties to research new availabilities, find additional property inventory, identify new construction, collect tenant information, verify existing information, photograph properties, and create high quality videos of interior spaces (including walk-through videos and Matterport 3D virtual tours), amenities, and exterior features of properties. A typical site inspection of a commercial property consists of photographing the building, capturing interior images, videos, and Matterport 3D tours, measuring the building, geo-coding the building, capturing “for-sale” or “for-lease” sign information, counting parking spaces, assessing property condition and construction, and gathering tenant information. Field researchers also canvass properties, collecting tenant data suite-by-suite.

We are leveraging our capabilities developed from our extensive commercial real estate research efforts to produce original, media rich content of neighborhoods, schools, parks, new home communities, condominium buildings' amenities, and common areas for our residential products. Our proprietary content is delivered at scale through a single integrated platform. Proprietary data, an integrated delivery platform and bespoke research processes underpin our product solutions. We use advanced technology, including AI, to improve data collection, data generation and data quality.

Data and Image Providers. We license a small portion of our data and images from public record providers and third-party data sources. Licensing agreements with these entities allow us to use a variety of commercial real estate information, including property ownership, tenant information, demographic information, maps, and aerial photographs, all of which enhance our services. These license agreements generally grant us a non-exclusive license to use the data and images in the creation and supplementation of our online marketplaces, information, and analytics.

Services

We operate, develop products, and deliver our services in two reportable segments, Commercial Real Estate and Residential Real Estate.

Commercial Real Estate

Our Commercial Real Estate segment offers commercial real estate information and analytics, online marketplaces, and 3D digital twin technology and its principal brands are:

CoStar

CoStar offers subscription-based access to our platform of commercial real estate intelligence with several key features:

*•*Properties - Provides a comprehensive inventory of various property types, including office, industrial, retail, multifamily, hospitality, student housing, and land. It includes for-lease and for-sale listings, historical data, property analytics, building photographs, demographics, maps, and floor plans. Users can identify available space, evaluate opportunities, value assets, and analyze market conditions.

• Leasing - Offers data on lease transactions and tools to manage user-entered lease data. Subscribers can analyze lease datasets and perform cash flow analysis from both landlord and tenant perspectives.

• Sales - A database of commercial real estate sales transactions, useful for researching property comparables, identifying market trends, expediting appraisals, and supporting property valuations.

• Tenants - Provides detailed tenant information, including lease expirations, occupancy levels, and growth rates, allowing users to target prospective clients.

• Owners - Provides detailed portfolio information, including lease expirations, occupancy levels, and growth rates, allowing users to target prospective clients.

• Markets - Enables viewing and reporting on market and submarket trends, including leasing, vacancy, rental rates, construction, investment sales, and economic conditions. It covers all major real estate sectors and provides forecasts.

• STR Benchmarking - Provides hospitality benchmarking, allowing hotels to measure performance against competitors based on occupancy, ADR, and RevPAR.

• Debt Solutions - Provides tools for lenders to manage loan portfolios and risk, including portfolio surveillance, concentration risk monitoring, stress testing, and expected credit loss modeling.

We also offer SaaS platforms and related professional services under the CoStar Real Estate Manager and Visual Lease brands which provide real estate and lease management technology solutions for lease administration, lease accounting, and transaction management.

LoopNet

LoopNet, the flagship brand of our network of commercial property marketing sites, is a top commercial real estate marketing site where property owners, landlords, and brokers can advertise properties for sale or lease on a site that supplements their listing with CoStar Group's database of property information and content. LoopNet offers a variety of subscription-based ad packages and enhancements. LoopNet Silver is designed for real estate professionals seeking maximum exposure and advanced marketing tools and markets listings to all LoopNet.com visitors. LoopNet Gold, Platinum, and Diamond Ads provide additional exposure on the LoopNet Network and retargeting across the web. With the Domain Acquisition, we also offer commercial real estate listings in Australia.

Other Commercial Real Estate Offerings

Our other Commercial Real Estate Offerings include:

• Matterport's 3D digital twins allow users to capture and share spaces in immersive 3D and access AI powered property insights. These services are sold on a subscription basis. Matterport also provides capture services of spatial data and other add-on services to existing subscription customers and sells 3D capture cameras and third-party capture devices to customers.

• BizBuySell is a marketplace for operating businesses and franchises for sale. Sellers pay to list their businesses, and buyers can search listings for free.

• Ten-X is a commercial real estate auction platform providing brokers, sellers, and buyers access to data-driven technology and marketing tools to expand market visibility and decrease time to close.

Residential Real Estate

Our residential marketplaces aggregate consumer demand for homes that they can rent or buy and we sell marketing and leads to the agents, owners, landlords, and property management companies that need to reach those consumers with their offerings. Our flagship brands in the U.S. are Apartments.com, Homes.com, and Land.com.

Apartments.com is the flagship brand of our network of apartment marketing sites which allow property owners and managers to showcase their apartment community through increased exposure and media rich interactions that allow renters to view, engage, and connect with the community.

Homes.com allows property owners and real estate agents to reach renters and buyers on a your-listing your lead basis. Powered by Homes AI, consumers can find their dream home by engaging in natural, real-time, two-way conversations - by voice or text - to search, refine, and explore homes in an interactive experience that feels less like navigating a website and more like being guided by a deeply knowledgeable, trusted real estate advisor. Homes AI draws from our unmatched depth of property data, Matterport 3D digital twin technology, images, proprietary school data, neighborhood insights, and market intelligence to deliver bespoke guidance that empowers shoppers with the resources and confidence they need to find the perfect home.

Land.com is a premier marketplace to discover, buy, and sell rural real estate. Properties listed include farms, ranches, timberland, hunting land, mountain property, lake houses, river homes, beachfront homes and country homes on acreage.

Domain and OnTheMarket are our leading marketplaces in Australia and the U.K., respectively allowing real estate agents to advertise their listings.

Our services are typically distributed to our clients under subscription-based license agreements that typically renew automatically, a majority of which have a term of at least one year. Upon renewal, many of the subscription contract rates may change in accordance with contract provisions or as a result of contract renegotiations. To encourage regular use of our services, we generally charge a fixed monthly subscription fee rather than fees based on actual platform usage or number of paid clicks. Depending on the type of service, contract rates are generally based on the number of sites, number of users, organization size, the client's business focus, the client's geographic location, the number of properties reported on or analyzed, the number and types of services to which a client subscribes, the number of digital twins hosted, the number of properties a customer advertises, and the prominence and placement of a customer's advertised properties in the search results. Our subscription customers generally pay contract fees on a monthly basis, but in some cases may pay us on a quarterly or annual basis. Our transaction-based services primarily consist of (1) providing premium listings for individual properties on our marketplaces, (ii) providing data capture services to create digital twins, (iii) the sale of Matterport cameras and capture equipment, and (iv) auction fees from our Ten-X online auction platform for commercial real estate, which are generally calculated as a percentage of the final sales price for the commercial real estate property sold and recognized as revenue upon the successful closing of the sale of the auctioned property.

Customers

A large number of parties involved in commercial and residential real estate industries and the related business community use the services to obtain information needed to conduct their businesses, including:

Our revenue streams are highly diversified. We are not presently dependent upon, and we do not anticipate becoming dependent upon, any one customer or a small number of customers.

Sales and Marketing

Our sales strategy focuses on optimal service for existing customers, attracting new clients, and cross-selling our solutions. Our sales teams, primarily located in field offices across the U.S., Canada, the U.K., Spain, France, Germany, and Australia, sell multiple products. Our inside sales teams, primarily based in Richmond, VA, work lead lists, prospect for new customers, and perform product demonstrations.

Local offices support field sales and research, providing clients with a local presence. Field sales teams handle customer service, client satisfaction, and relationship building. Local offices also serve as hubs for training, market insights, product feedback, and industry connections. We manage client accounts through frequent meetings, product training, and updates on new enhancements.

In 2025, we implemented targeted sales and marketing campaigns aimed at agents, brokers, property owners, investors, corporate and retail tenants and occupiers, as well as financial institutions and lenders in the United States, and will continue these efforts into 2026. Our marketing activities include in-person and virtual product demonstrations, targeted digital and social media campaigns, direct marketing, corporate and campaign-specific websites, press releases, earned media, participation in trade shows and industry events, company-hosted events, client referrals, and content marketing.

Digital and direct marketing, including SEM, SEO, paid advertising, social media, and display advertising, help us find prospective clients. Service demonstrations are our most effective sales method. We sponsor and attend industry events to reinforce relationships with core user groups.

For Apartments.com and Homes.com, we use multi-channel marketing campaigns, including TV, radio, online ads, social media, email, public relations, SEM, and SEO. We plan to continue these methods and apply similar strategies for LoopNet, optimizing marketing investments.

Expansion and Growth

We have expanded, and continue to expand, the coverage and depth of our online marketplace services, information, and analytics. We plan to continue to invest in our business and services, evaluate strategic growth opportunities, and pursue our key priorities as described below in Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations.

In addition to organic growth, we have grown our business through strategic acquisitions. We acquired Visual Lease, Matterport, and Domain in November 2024, February 2025, and August 2025, respectively. We continue to integrate our recent acquisitions and the services they offer into our CoStar network.

See Notes 4 and 8 of the Notes to the Consolidated Financial Statements included in Part IV of this Report, for further discussion of these acquisitions.

Proprietary Technology

Our IT professionals develop and enhance services for customers, maintain existing services, integrate current offerings, secure our real estate data, and provide research automation tools to improve data quality and research efficiency. They are responsible for our online marketplace services, analytics, and infrastructure, and for implementing technologies designed to increase research capacity and support data quality. Unique AI-enabled data collection and quality control mechanisms have been developed, and our enterprise information management system integrates sales, research, customer support, and accounting information. This system supports commercial real estate research, contact management, workflow automation, and daily quality checks. Additionally, fraud-detection and adaptive authentication technologies have been implemented to prevent unauthorized access. Our IT team also maintains servers and network components, ensuring uninterrupted service from multiple data centers and cloud platforms, with continuous monitoring for fast, reliable access and security.

Segment Reporting

During the fourth quarter of 2025, we changed the composition of our segments from geography-based to product portfolio-based discussed under our Services above. This change aligns with the internal reporting used by the CODM to allocate resources and assess the performance of the business. See Notes 2, 3 and 13 of the Notes to the Consolidated Financial Statements included in Part IV of this Report for additional information on the segments change and revenue, significant expenses, EBITDA, and Adjusted EBITDA for each of our segments.

Competition

Our business depends on our ability to successfully provide real estate industry professionals and consumers with comprehensive, timely, and standardized information and arm them with the right tools to use, analyze, and transact in the information.

The market for real estate-focused online marketplaces, information, and analytics generally is competitive, dynamic, and is constantly evolving as a result of technological advancements, customer preferences, and new products and offerings. As a result of our unique combination of products and services, we find that we compete with a variety of companies that provide online real estate-focused marketplace and internet listing services, publish and distribute information, benchmarks, and analytics, and provide marketing, real estate portfolio and lease management, and administrative software solutions.

Competitive factors may vary across each of our Commercial Real Estate and Residential Real Estate segments and marketplaces; however, we believe we primarily compete on the basis of:

• Quality and depth of the underlying databases;

• Quality and quantity of leads and, for multifamily, leases delivered;

• Ease of use, flexibility, and functionality of the software;

• Intuitiveness and appeal of the user interface;

• Timeliness of the data, including listings;

• Breadth of geographic coverage and services offered;

• Completeness and accuracy of content;

• Client service and support;

• Perception that the service offered is the industry standard;

• Price;

• Effectiveness of marketing and sales efforts;

• Proprietary nature of methodologies, databases, and technical resources;

• Vendor reputation;

• Brand awareness and reputation, and satisfaction and loyalty among customers;

• Adaptive and advanced technology;

• Capital resources;

• Quality and size of real, authenticated and intent-driven unique platform visitors; and

• Use of AI both in our products and in our internal operations.

Many of our competitors, especially with respect to those that compete with our businesses in our Residential Real Estate segment, are incumbent players that may have greater name recognition, resources, and increased adoption of AI services. Generally, as markets for real estate-focused online marketplaces, information, and analytics develop, additional competitors

(including companies that could have greater access to data, financial, product development, technical, analytic, or marketing resources than we do) may enter a market, and competition may intensify.

Proprietary Rights

To protect our proprietary rights in our methodologies, database, software, trademarks, and other intellectual property, we depend upon a combination of laws related to:

• Trade secret, misappropriation, unfair competition, copyright, trademark, computer fraud, database protection, and other laws;

• Registration of copyrights and trademarks;

• Nondisclosure, and other contractual provisions with employees and consultants;

• License agreements with customers;

• Patent protection; and

• Technical measures.

We seek to protect our software’s source code, our database, and our photography as trade secrets and under copyright law. Although copyright registration is not a prerequisite for copyright protection, we have filed for copyright registration for many of our databases, photographs, software, and other materials. Under current U.S. copyright law, the arrangement and selection of data may be protected, but the actual data itself may not be. Certain U.K. database protection laws provide additional protections for our U.K. databases. We generally license our services under license agreements that grant our clients non-exclusive, non-transferable rights. These agreements restrict the disclosure and use of our information and prohibit the unauthorized reproduction or transfer of any of our proprietary information, methodologies, or analytics.

We also attempt to protect our proprietary databases, trade secrets, and proprietary information through confidentiality and agreements with our employees and consultants. Our services also include technical measures designed to detect, discourage, and prevent unauthorized access to and/or copying of our intellectual property. We have established an internal antipiracy team that uses fraud-detection technology to continually monitor use of our services to detect and prevent unauthorized access, and we actively prosecute individuals and firms that engage in this unlawful activity.

We maintain U.S. and international trademark registrations for CoStar Group’s core service names and proactively file U.S. and international trademark applications covering our new and planned service names. We own U.S. federally registered trademarks for our brands and services including Apartments.com®, CoStar®, Domain®, Homes.com®, Land.com®, LoopNet®, Matterport®, and Visual Lease®, among many others. In the U.S., trademarks are generally valid so long as they are in use and are capable of indicating CoStar Group as the source of services. We consider our trademarks in the aggregate to constitute a valuable asset.

In addition, we maintain a patent portfolio that protects certain of our systems and methodologies. We currently have over 100 issued patents, with 96 of those issued in the United States. Our patent portfolio covers, among other things, our interface features, as well as the technology at the core of Matterport. We regard the rights protected by our patents as valuable to our business, but do not believe that our business is materially dependent on any single patent or portfolio of patents as a whole.

Governmental Regulation

As a public company with global operations, we are subject to various federal, state, local, and foreign laws and regulations. These laws and regulations, which may differ among jurisdictions, include, those related to financial and other disclosures, accounting standards, privacy and data protection, intellectual property, corporate governance, taxation, government contracting, trade, antitrust, employment, immigration and travel, and anti-corruption. The costs to comply with these governmental regulations are not material to the understanding of our business. For a further discussion of the risks associated with government regulations that may materially impact us, see “Risk Factors” included in Part I, Item 1A of this report.

Human Capital Resources

Our people at CoStar Group are our greatest asset. With over 8,000 employees in 20 countries, our business is built on delivering excellence and innovation to our clients and supporting a workplace where our people can thrive.

CoStar Group’s core values define our culture and guide the behaviors that enable our teams to work collaboratively toward our shared mission of digitizing the world’s real estate. We have designed our human capital resources to strengthen our

teams’ skills, drive business growth, support community and belonging, and reward successful outcomes with best-in-class compensation and benefits programs.

In 2025, we expanded our in-person and online corporate training and development programs to the United Kingdom (and plan to expand them to colleagues in Australia). Our extensive sales training programs include in-depth new hire onboarding designed to accelerate growth, strengthen performance, and elevate the experience of every seller. We also launched several new continuous learning and coaching initiatives, including Leadership Labs, a knowledge-sharing forum for experienced leaders, Coach the Coach, which helps sales leaders refine their coaching skills and drive sustained team performance, and the Leaderboard to Leadership program, which develops high-performing individual contributors into future sales leaders.

To assess employee engagement, we partner with a third-party vendor to conduct annual employee surveys. Insights and results gathered from the survey are shared with our leadership, managers, and employees, and inform our learning and development, communication, leadership, and employee experience strategies each year.

The diversity of thought that comes from different perspectives and backgrounds enables us to design cutting-edge research, marketplace, and technology solutions that best serve our customers. Our Culture team, in collaboration with our employee resource groups, offers various culture and community engagement programs and educational opportunities to promote a sense of belonging and foster an inclusive environment for all individuals, regardless of their background.

CoStar Group’s total rewards approach provides competitive pay and benefits to attract and retain top talent. In addition to base salaries, compensation may include annual bonuses, commissions, and equity awards. Our comprehensive set of health and wellness benefits is both affordable and high quality, offering valuable support to employees and their families. While benefits and wellness offerings vary by location, they can include health care coverage, retirement benefits with company contributions, life and disability insurance, access to counseling and resources related to mental health, time away policies, tuition assistance, service awards of CoStar Group Shares, college savings benefits, company subsidized commuter benefits, legal services, employee stock purchase plan, and pet insurance.

As of January 31, 2026, we employed:

• 6,602 U.S.-based employees, representing approximately 78% of the overall employee population

• 1,155 employees in Asia and Oceania

• 608 employees in Europe

• 72 employees in Canada

• 4 employees in Latin America

No CoStar Group employees are represented by a labor union, and we have not experienced any work stoppages to date.

As is common with many German companies, employees in our German subsidiary, Thomas Daily GmbH, have elected four fellow employees to form a Works Council (Betriebsrat), which represents their interests at the location. The Works Council has certain co-determination rights and rights to receive information from us and engage us in discussions under applicable law. In France, both Business Immo Holdings and ComReal have Works Councils (known as comité social et économique, or CSE) which are employee representative bodies.

Available Information

Our investor relations internet website is http://www.costargroup.com/investors. The reports we file with or furnish to the SEC, including our annual report, quarterly reports, and current reports, as well as amendments to those reports, are available free of charge on our internet website as soon as reasonably practicable after we electronically file such material with, or furnish it to, the SEC. The SEC maintains an internet site that contains reports, proxy statements, information statements, and other information regarding issuers that file electronically with the SEC at https://www.sec.gov.

Summary of Risk Factors

Risks related to our business

*We may not be able to attract and retain new clients, which could adversely affect our revenue and financial position. Our success and revenue depend on attracting and retaining subscribers to our information, analytics, and online marketplace services, which generate the largest portio

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None.

Cybersecurity Risk Management and Strategy

We have developed and implemented a cybersecurity risk management program intended to protect the confidentiality, integrity, and availability of our critical systems and information.

Our cybersecurity risk management program is guided by the National Institute of Standards and Technology Cybersecurity Framework (NIST CSF). This does not imply that we meet any particular technical standards, specifications, or requirements at all times; rather, we use the NIST CSF as a guide to help us identify, assess, and manage cybersecurity risks

relevant to our business. Additionally, we engage a third-party vendor regularly to benchmark our information security program’s maturity against the NIST CSF.

Our cybersecurity risk management program is integrated into our overall risk management program and shares common methodologies, reporting channels, and governance processes that apply across the Company's risk management program.

Key elements of our cybersecurity risk management program include, but are not limited to the following:

a.Internal and external asset identification, assessment, monitoring, and classification procedures to evaluate cybersecurity risks and inform mitigation efforts;

b.A security team principally responsible for managing (1) our cybersecurity risk assessment processes, (2) our cyber processes, and (3) our cyber threat and incident response;

c.The use of external service providers, where appropriate, to assess defenses, analyze threat intelligence, or otherwise assist with aspects of our security controls;

d.Cybersecurity awareness training of our employees, software development teams, incident response personnel, and senior management;

e.A cybersecurity incident response plan that includes procedures for responding to cybersecurity incidents; and regular tabletop exercises to assess our response readiness;

f.A third-party risk management process for key service providers, suppliers, and vendors who access critical systems and data based on risk profile; and

g.A formal information security training program for all employees.

We have not identified material risks from known cybersecurity threats, including as a result of any prior cybersecurity incidents that have materially affected our operations, business strategy, results of operations, or financial condition. We face certain ongoing risks from cybersecurity threats that, if realized, are reasonably likely to materially affect us, including our operations, business strategy, results of operations, or financial condition. See Risk Factors – “Cyberattacks and security vulnerabilities could result in material harm to our reputation, business, and financial condition.” and “Technical problems or disruptions that affect either our customers’ ability to access our services, or the software, internal applications, database, and network systems underlying our services, could damage our reputation and lead to reduced demand for our online marketplace services, information, and analytics, lower revenue and increase costs.”

Cybersecurity Governance

Our Board of Directors considers cybersecurity risk as part of its risk oversight function and has delegated to the Audit Committee oversight of cybersecurity and generative AI risks, controls, and procedures. Our Chief Technology Officer (CTO) is responsible for oversight of our cybersecurity risk management program. Our Vice President of Cyber Security (VPCS), who reports up to the CTO, is responsible for day-to-day assessment and management of cybersecurity risk, including supervising both our internal cybersecurity personnel and our retained external cybersecurity consultants. Our CTO is also responsible for overseeing the material risks and strategic opportunities associated with AI.

Our Audit Committee receives reports from the CTO on our cybersecurity risks and our use of AI. In addition, the CTO updates the Audit Committee, as necessary, regarding any significant cybersecurity incidents. The Audit Committee reports to the full Board of Directors regarding its activities, including those related to cybersecurity and AI.

Our CTO and VPCS assist the management team in staying informed about and monitoring the prevention, detection, mitigation, and remediation of cybersecurity threats. Our CTO has over 25 years of information technology experience, including leadership experience managing global product development, information security, IT infrastructure and engineering. He holds a M.S. in information systems from George Washington University and a B.A. in computer science from State University of New York—Geneseo. The VPCS has over 20 years of information security and technology experience, including 10 years in senior leadership roles in service provider, enterprise, and military environments. He holds an MBA from Georgetown University, a M.S. in information systems from Virginia Tech University, and a B.S. in computer information technology from Purdue University. Additionally, our management team’s experience includes industry-recognized certifications, such as CISSP, CISM, and CISA, decades of experience as part of our IT team, and previous cybersecurity leadership positions at various Fortune 500 companies and U.S. Defense contractors.

The CTO and VPCS are informed about and monitor the prevention, detection, mitigation, and remediation of cybersecurity risks and incidents through various means, which may include briefings from internal security personnel; threat intelligence and other information obtained from governmental, public, or private sources, including external consultants engaged by us; and alerts and reports produced by security tools deployed in the IT environment.

On January 21, 2025, we relocated our headquarters to our owned building at 1201 Wilson Blvd., in Arlington, Virginia, occupying approximately 198,000 square feet. We exited our previous headquarters located at 1331 L Street, NW, in downtown Washington, D.C., with a lease that expired on May 31, 2025.

Our staff in Richmond, Virginia is located in an owned building at 501 S 5th Street, where we occupy approximately 310,000 square feet, an owned building located at 901 Semmes Avenue, where we occupy approximately 117,000 square feet, leased space at 951 E Byrd St., where we occupy approximately 165,000 square feet, and leased space at 901 E Byrd St., where we occupy approximately 46,000 square feet. These locations primarily house research, product development, and sales functions. All of our owned properties are held under fee simple ownership and are not materially encumbered.

Internationally, our principal facility in the U.K. is located in London, where we occupy approximately 52,000 square feet of office space. Our lease for this facility has a term ending November 10, 2034. We exited our previous London location when the lease expired on August 31, 2025. Our principal facility in Australia is located in Sydney, where we occupy approximately 95,000 square feet, with a lease term ending June 30, 2031. Additionally, we lease space for our operations in Paris, France; Madrid, Spain; Freiburg, Germany; and Manila, Philippines.

We also operate certain research, development, and sales functions out of additional leased office spaces in Irvine, California; San Diego, California; and Atlanta, Georgia. Additionally, we lease office space in a variety of other metropolitan areas. These locations include, among others, the following: Nashville, Tennessee; Norfolk, Virginia; Boston, Massachusetts; New York, New York; San Francisco, California; Los Angeles, California; and Sunnyvale, California.

We believe these facilities are suitable and appropriately support our business needs.

Currently, and from time to time, we are involved in litigation incidental to the conduct of our business, including, among others, the legal actions discussed under “Contingencies” in Note 12 “Commitments and Contingencies” of the Notes to our Consolidated Financial Statements included in Part IV of this Report. While our management presently believes that the ultimate outcome of these proceedings, individually and in the aggregate, will not materially harm our business, financial position, future results of operations, or liquidity, legal proceedings are inherently uncertain, and unfavorable rulings could, individually or in the aggregate, have a material adverse effect on our business, financial position, future results of operations, or liquidity.

Not Applicable.

PART II

Our common stock is traded on the Nasdaq Global Select Market under the symbol “CSGP.” As of January 31, 2026, there were 1,620 holders of record of our common stock.

Dividend Policy. We have never declared or paid any dividends on our common stock. We do not anticipate paying any dividends on our common stock during the foreseeable future, but intend to invest our future earnings, if any, to finance our growth and share repurchases.

Recent Issues of Unregistered Securities. We did not issue any unregistered securities during the year ended December 31, 2025.

Issuer Purchases of Equity Securities. The following table summarizes our repurchases of common stock for the quarter ended December 31, 2025 (in millions, except per share data):

ISSUER PURCHASES OF EQUITY SECURITIES

(1) The number includes CoStar Group Shares tendered by employees to the Company to satisfy the employees' minimum tax withholding obligations arising as a result of vesting of restricted stock grants under the Company’s 2025 Stock Incentive Plan, for which shares were purchased by the Company based on their fair market value on the trading day immediately preceding the vesting date.

(2) In February 2025, the Board of Directors approved the Prior Stock Repurchase Program which authorized the repurchase up to $500 million of Costar Group Shares. During the fourth quarter of 2025, the Company repurchased 5.7 million CoStar Group Shares for an aggregate cost of $385 million under the Prior Stock Repurchase Program. The repurchases under the Prior Stock Repurchase Agreement were completed in December 2025. In December 2025, the Board of Directors approved a Stock Repurchase Program which authorizes, but does not obligate, the repurchase of up to $1.5 billion of CoStar Group Shares. No shares were repurchased under the Stock Repurchase Program during the fourth quarter of 2025. See Note 14 for further discussion regarding the Prior Stock Repurchase Program, Stock Repurchase Program, and stock repurchase activity.

Stock Price Performance Graph

The stock performance graph below shows how an initial investment of $100 in our common stock would have compared to:

• an equal investment in the S&P 500 Index, and

• an equal investment in the S&P Composite 1500 Real Estate Index.

The comparison covers the period beginning December 31, 2020 and ending on December 31, 2025, and assumes the reinvestment of any dividends. Note that this performance is historical and is not necessarily indicative of future price performance.

The following Management’s Discussion and Analysis of Financial Condition and Results of Operations contains “forward-looking statements,” including statements about our beliefs and expectations. There are many risks and uncertainties that could cause actual results to differ materially from those discussed in the forward-looking statements. Potential factors that could cause actual results to differ materially from those discussed in any forward-looking statements include, but are not limited to, those stated under the heading “Cautionary Statement Concerning Forward-Looking Statements” and in Item 1A. under the heading “Risk Factors,” as well as those described from time to time in our filings with the SEC.

All forward-looking statements are based on information available to us on the date of this filing and we assume no obligation to update such statements, whether as a result of new information, future events, or otherwise, except as required by applicable law. The following discussion should be read in conjunction with our Quarterly Reports on Form 10-Q, Current Reports on Form 8-K, other filings with the SEC, and the consolidated financial statements and related notes included in Part IV of this Report.

Overview

CoStar Group is a leading provider of online real estate marketplaces, information, analytics, and 3D digital twin technology in the property markets, based on the numbers of unique visitors and site visits per month; provides more information, analytics, and marketing services than many of our competitors; offers the most comprehensive commercial real estate database available; and has the largest commercial real estate research department in the industry. We have created and compiled a standardized platform of real estate information and analytics and online marketplaces where industry professionals, consumers of commercial and residential real estate, including apartments, and the related business communities, can continuously interact and facilitate transactions by efficiently accessing and exchanging accurate and standardized real estate-related information. Our service offerings span all property types, including office, retail, industrial, multifamily, residential, land, mixed-use, and hospitality.

We operate, develop products, and deliver our services in two reportable segments, Commercial Real Estate and Residential Real Estate. Our Commercial Real Estate segment offers commercial real estate information and analytics, online marketplaces, and 3D digital twin technology and its principal brands are CoStar, including CoStar Real Estate Manager and CoStar with STR benchmarking, LoopNet, Matterport, BizBuySell, and Ten-X. Our Residential Real Estate segment hosts marketplaces which aggregate consumer demand for homes that they can rent or buy and we sell marketing and leads to the agents, owners, landlords, and property management companies that need to reach those consumers with their offerings. Our flagship brands in the U.S. are Apartments.com, Homes.com, and Land.com. Domain and OnTheMarket are our leading marketplaces in Australia and the U.K., respectively.

During the fourth quarter of 2025, we changed the composition of our segments from geography-based to product portfolio-based. This change aligns with the internal reporting used by the CODM to allocate resources and assess the performance of the business. See Notes 2, 3 and 13 of the Notes to the Consolidated Financial Statements included in Part IV of this Report for additional information on the segments change.

Our services are primarily derived from a database of building-specific information and offer customers specialized tools for accessing, analyzing, and using our information. Over time, we have enhanced and expanded, and we expect to continue to enhance and expand, our existing information, analytics, and online marketplaces. We have developed and we expect to continue to develop additional services leveraging our centralized database and 3D digital twin technology to meet the needs of our existing customers as well as potential new categories of customers.

Our services are typically distributed to our customers under subscription-based license agreements that generally renew automatically, a majority of which have a term of at least one year. Upon renewal, many of the subscription contract rates may change in accordance with contract provisions or as a result of contract renegotiations. To encourage customers to use our

services regularly, we generally charge a fixed monthly amount for our subscription-based services rather than charging fees based on actual platform usage or number of paid clicks. Depending on the type of service, contract rates are generally based on the number of sites, number of users, organization size, the customer’s business focus, the customer's geographic location, the number of properties reported on or analyzed, the number and types of services to which a customer subscribes, the number of digital twins hosted, the number of properties a customer advertises, and the prominence and placement of a customer's advertised properties in the search results. Our subscription customers generally pay contract fees on a monthly basis, but in some cases may pay us on a quarterly or annual basis. Our transaction-based services primarily consist of (i) providing premium listings for individual properties on our marketplaces, (ii) providing data capture services to create digital twins, (iii) the sale of Matterport cameras and capture equipment, and (iv) Ten-X auction fees.

Our principal services are described in the following paragraphs:

Commercial Real Estate

CoStar

CoStar is our subscription-based integrated platform for commercial real estate intelligence, which includes information about commercial real estate properties, properties for sale, comparable sales, tenants, space available for lease, industry professionals and their business relationships, industry news, and market status. CoStar also provides benchmarking for the hospitality industry under the STR brand, lease analytical capabilities, and risk management and other debt solutions for lenders. We also offer SaaS for lease management under the CoStar Real Estate Manager and Visual Lease brands.

LoopNet

Our LoopNet Network of commercial real estate websites offers online marketplace services that enable commercial property owners, landlords, and real estate agents working on their behalf to advertise properties for sale or for lease. Commercial real estate agents, buyers, and tenants use the LoopNet Network of online marketplace services to search for available property listings that meet their criteria. With the Domain Acquisition, we also offer commercial real estate listings in Australia.

Other Commercial Real Estate

Other Commercial Real Estate includes revenue from the Matterport Acquisition, BizBuySell Network, and Ten-X's online auctions for commercial real estate. Matterport primarily provides hosting services for its 3D digital twins on a subscription basis. Matterport also provides capture services of spatial data and other add-on services to existing subscription customers and sells 3D capture cameras and accessories. Our BizBuySell Network provides online marketplaces for businesses and franchises for sale.

We expect Commercial Real Estate's revenue growth rate for the year ending December 31, 2026 to moderate compared to the revenue growth rate for the year ended December 31, 2025, due to the lack of benefit from the Matterport Acquisition realized in 2025.

Residential Real Estate

Our residential marketplaces enable renters and homebuyers to find their dream homes by combining our proprietary research and neighborhood content with listing information, while enabling property owners, managers, and real estate agents to advertise their properties. Our flagship brands in the U.S. are Apartments.com, Homes.com, and Land.com. Apartments.com

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We provide information, analytics, and online marketplace services to real estate and related business communities within the regions where we operate, which primarily include North America, Asia-Pacific, Europe, and Latin America. The functional currency for a majority of our operations is the local currency, with the exception of certain international locations for which the functional currency is the British Pound or U.S. Dollar.

Fluctuations in the British Pound, Canadian Dollar, Australian Dollar, and Euro may have an impact on our business, results of operations, and financial position. For the years ended December 31, 2025 and December 31, 2024, revenue denominated in foreign currencies were approximately 9% and 5% of total revenue, respectively. For the years ended December 31, 2025 and December 31, 2024, our revenue would have decreased by approximately $29 million and $14 million, respectively, if the U.S. dollar exchange rate used strengthened by 10%. For the years ended December 31, 2025 and December 31, 2024, our revenue would have increased by approximately $29 million and $14 million, respectively, if the U.S. dollar exchange rate used weakened by 10%. In addition, we have assets and liabilities denominated in foreign currencies. As of December 31, 2025, accumulated other comprehensive loss included a gain from foreign currency translation adjustments of approximately $80 million.

We do not believe we have material exposure to market risks associated with changes in interest rates related to cash equivalent securities held as of December 31, 2025. As of December 31, 2025, we had $1.7 billion of cash, cash equivalents,

and restricted cash. If there is an increase or decrease in interest rates, there will be a corresponding increase or decrease in the amount of interest earned on our cash and cash equivalents. We currently diversify our cash and cash equivalents holdings amongst multiple financial institutions and AAA-rated Government and Treasury Money Market Funds.

We are subject to interest rate market risk in connection with our revolving credit facility. On May 20, 2024, we entered into the 2024 Credit Agreement, which provides for variable rate borrowings of up to $1.1 billion. On July 1, 2020, we issued $1.0 billion aggregate principal amount of Senior Notes. Changes in interest rates would not have a material impact to our current interest and debt financing expense, as all of our borrowings except for our credit facility are fixed rate, and no amounts were outstanding under our credit facility as of December 31, 2025. See Note 10 of the Notes to the Consolidated Financial Statements included in Part IV of this Report for additional information regarding our 2024 Credit Agreement.

We had approximately $6.7 billion of goodwill and intangible assets as of December 31, 2025. As of December 31, 2025, we believe our intangible assets will be recoverable; however, changes in the economy, the industry in which we operate, and our own relative performance could change the assumptions used to evaluate intangible asset recoverability. In the event that we determine that an asset has been impaired, we would recognize an impairment charge equal to the amount by which the carrying amount of the asset exceeds its fair value. We continue to monitor these assumptions and their effect on the estimated recoverability of our intangible assets.

Financial Statements meeting the requirements of Regulation S-X, including reports of independent registered public accounting firm Ernst & Young LLP, are set forth beginning at page F-1. Supplementary data is set forth in “Management’s Discussion and Analysis of Financial Condition and Results of Operations” under the caption “Consolidated Results of Operations.”

None.

We maintain disclosure controls and procedures designed to ensure that information required to be disclosed in our reports filed or submitted under the Exchange Act is recorded, processed, summarized, and reported, within the time periods specified in the SEC’s rules and forms. These controls also are designed to ensure that such information is accumulated and communicated to our management, including our Chief Executive Officer and Chief Financial Officer, as appropriate, to allow for timely decisions regarding required disclosure. In designing and evaluating the disclosure controls and procedures, management recognizes that any systems of controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving its objectives. Accordingly, management is required to apply judgment in evaluating the cost-benefit relationship of possible controls and procedures.

As of December 31, 2025, under the supervision and with the participation of our management, including our Chief Executive Officer and our Chief Financial Officer, we evaluated the effectiveness of our disclosure controls and procedures. Based on this evaluation, our Chief Executive Officer and Chief Financial Officer concluded that our disclosure controls and procedures were effective as of December 31, 2025, and were operating at a reasonable assurance level.

We are continuing to integrate the internal controls over financial reporting of recent acquisitions. These activities may require modifications to certain processes, systems, and other components of internal controls over financial reporting. Consistent with our process changes, we evaluate the design and effectiveness of the internal controls as part of our overall assessment of disclosure controls and procedures.

Other than the integration activities associated with recent acquisitions, there were no changes in our internal control over financial reporting during the most recent fiscal quarter that have materially affected, or are reasonably likely to materially affect our internal control over financial reporting.

Management’s Annual Report on Internal Control over Financial Reporting

Management of CoStar Group is responsible for establishing and maintaining adequate internal control over financial reporting and assessing its effectiveness. Internal control over financial reporting, as defined by the SEC, is a process designed by, or under the supervision of, the Company’s principal executive and principal financial officers to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements in accordance with GAAP.

Our internal control over financial reporting is supported by written policies and procedures, which (1) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect transactions and asset dispositions; (2) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with GAAP, and that receipts and expenditures are made only in accordance with management's and directors' authorization; and (3) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of assets that could have a material effect on the financial statements.

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate due to changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

Management assessed the effectiveness of internal control over financial reporting as of December 31, 2025, using the criteria established in Internal Control – Integrated Framework (2013 framework) issued by COSO. This assessment included evaluating the design and testing of the operational effectiveness of our internal control over financial reporting. Based on this assessment, management concluded that internal control over financial reporting was effective as of December 31, 2025.

Ernst & Young LLP, our independent registered public accounting firm, audited the financial statements included in this report and issued an attestation report on the effectiveness of internal control over financial reporting, a copy of which is included in this Report.

CoStar Group completed the Matterport Acquisition and Domain Acquisition in February 2025 and August 2025, respectively. As permitted by the SEC, we have elected to exclude the internal controls of these acquisitions, which have not been integrated into our existing processes and controls, from our assessment of the effectiveness of internal control over financial reporting as of December 31, 2025. The excluded financial position of Matterport and Domain collectively represented less than 5% of our total assets, excluding the preliminary value of goodwill and other intangible assets as of December 31, 2025, and less than 10% of our revenue for the year then ended. We will include the internal controls of Matterport and Domain in our assessment of the effectiveness of our internal control over financial reporting as of December 31, 2026.

Insider Trading Arrangements Intended to Satisfy the Affirmative Defense of Rule 10b5-1(c)

During the three months ended December 31, 2025, two officers of the Company entered into trading plans intended to satisfy the affirmative defense of Rule 10b5-1(c) of the Exchange Act (each such trading plan, a "Plan"), as discussed below.

On November 14, 2025, Cynthia Cann, Chief Accounting Officer, entered into a Plan that provides for the sale of up to 3,986 CoStar Group Shares. Ms. Cann’s plan terminates on July 31, 2026, for a duration of 259 days.

On December 4, 2025, Michael Desmarais, Chief Human Resources Officer, entered into a Plan that provides for the sale of up to 5,000 CoStar Group Shares. Mr. Desmarais's Plan terminates on July 31, 2026, for a duration of 239 days.

During the three months ended December 31, 2025, no other directors or officers, as defined in Rule 16a-1(f), adopted or terminated a “Rule 10b5-1 trading arrangement” or a “non-Rule 10b5-1 trading arrangement,” each as defined in Item 408 of Regulation S-K.

Not applicable.

PART III

CoStar Group has adopted a Code of Business Conduct and Ethics for its directors, officers, contractors, and employees, including its principal executive, financial and accounting officers, or persons performing similar functions. Copies of the Code may be found in the “Investors” section of the Company’s website at https://investors.costargroup.com/corporate-governance/governance-documents. We intend to disclose future amendments to certain provisions of our Codes, or waivers of such provisions granted to executive officers and directors, as required by the SEC rules on the Company's website within four business days following the date of such amendment or waiver.

We have adopted an Insider Trading Compliance Policy that governs the purchase, sale, and/or other dispositions of our securities by directors, officers, and employees that is reasonably designed to promote compliance with insider trading laws, rules, regulations, and NYSE listing standards. A copy of our Insider Trading Compliance Policy is included as Exhibit 19.1 to this Report.

The remaining information required by this Item is incorporated by reference to our Proxy Statement for our 2026 annual meeting of stockholders under the captions “Director Nominees,” “Executive Officers,” Corporate Governance Highlights,” “Board Committees,” “Insider trading arrangements and policies,” and, if applicable, “Delinquent Section 16(a) Reports.”

The information required by this Item is incorporated by reference to our Proxy Statement for our 2026 annual meeting of stockholders under the captions “Compensation Discussion and Analysis,” “Director Compensation,” “Compensation Committee Interlocks and Insider Participation,” and “Compensation Committee Report.”

The information required by this Item is incorporated by reference to our Proxy Statement for our 2026 annual meeting of stockholders under the captions “Equity Compensation Plan Information” and “Stock Ownership Information.”

The information required by this Item is incorporated by reference to our Proxy Statement for our 2026 annual meeting of stockholders under the captions “Certain Relationships and Related Transactions” and “Corporate Governance Matters.”

The information required by this Item is incorporated by reference to our Proxy Statement for our 2026 annual meeting of stockholders under the caption “Ratification of the Appointment of Independent Registered Public Accounting Firm.”

PART IV

(a)(1) The following financial statements are filed as a part of this Report: CoStar Group, Inc. Consolidated Financial Statements.

(a)(2) Financial statement schedules: Additional financial statement schedules are omitted because they are not applicable or not required or because the required information is incorporated herein by reference or included in the financial statements or related notes included elsewhere in this report.

(a)(3) The documents required to be filed as exhibits to this Report under Item 601 of Regulation S-K are listed as follows:

Exhibits

• Management Contract or Compensatory Plan or Arrangement.

Schedules and exhibits (or similar attachments) have been omitted from this exhibit pursuant to Item 601(a)(5) of Regulation S-K. The Company will furnish copies of the such schedules (or similar attachments) to the SEC upon request.

None.

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

KNOW ALL PERSONS BY THESE PRESENTS, that each individual whose signature appears below constitutes and appoints Andrew C. Florance and Christian M. Lown, and each of them individually, as their true and lawful attorneys-in-fact and agents, with full power of substitution, for him and in his name, place and stead, in any and all capacities, to sign any and all amendments to this report, and to file the same, with all exhibits thereto and to all documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents, and each of them, full power and authority to do and perform each and every act and thing requisite and necessary to be done in connection therewith, as fully to all intents and purposes as he might or could do in person, herein by ratifying and confirming all that said attorneys-in-fact and agents or any of them, or his or their substitute or substitutes, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1934, as amended, this report has been signed by the following persons on behalf of the registrant and in the capacities and on the dates indicated.

COSTAR GROUP, INC.

INDEX TO CONSOLIDATED FINANCIAL STATEMENTS

F-1

Report of Independent Registered Public Accounting Firm

To the Stockholders and the Board of Directors of CoStar Group, Inc.

Opinion on the Financial Statements

We have audited the accompanying consolidated balance sheets of CoStar Group, Inc. (the Company) as of December 31, 2025 and 2024, the related consolidated statements of operations, comprehensive income, changes in stockholders’ equity and cash flows for each of the three years in the period ended December 31, 2025, and the related notes (collectively referred to as the “consolidated financial statements”). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company at December 31, 2025 and 2024, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2025, in conformity with U.S. generally accepted accounting principles.

We also have audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the Company's internal control over financial reporting as of December 31, 2025, based on criteria established in Internal Control-Integrated Framework issued by the Committee of Sponsoring Organizations of the Treadway Commission (2013 framework), and our report dated February 25, 2026 expressed an unqualified opinion thereon.

Basis for Opinion

These financial statements are the responsibility of the Company's management. Our responsibility is to express an opinion on the Company’s financial statements based on our audits. We are a public accounting firm registered with the PCAOB and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statemen

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