Item 9A. Controls and Procedures

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.