Five9 Inc

To the Stockholders and Board of Directors

Five9, Inc.:

Opinions on the Consolidated Financial Statements and Internal Control Over Financial Reporting

We have audited the accompanying consolidated balance sheets of Five9, Inc. and subsidiaries (the Company) as of December 31, 2024 and 2023, the related consolidated statements of operations and comprehensive loss, stockholders’ equity, and cash flows for each of the years in the three-year period ended December 31, 2024, and the related notes (collectively, the consolidated financial statements). We also have audited the Company’s internal control over financial reporting as of December 31, 2024, based on criteria established in Internal Control – Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission.

In our opinion, the consolidated financial statements referred to above present fairly, in all material respects, the financial position of the Company as of December 31, 2024 and 2023, and the results of its operations and its cash flows for each of the years in the three-year period ended December 31, 2024, in conformity with U.S. generally accepted accounting principles. Also in our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, 2024 based on criteria established in Internal Control – Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission.

Basis for Opinions

The Company’s management is responsible for these consolidated financial statements, for maintaining effective internal control over financial reporting, and for its assessment of the effectiveness of internal control over financial reporting, included in the accompanying Management’s Annual Report on Internal Control Over Financial Reporting. Our responsibility is to express an opinion on the Company’s consolidated financial statements and an opinion on the Company’s internal control over financial reporting based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (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 audits to obtain reasonable assurance about whether the consolidated financial statements are free of material misstatement, whether due to error or fraud, and whether effective internal control over financial reporting was maintained in all material respects.

Our audits of the consolidated financial statements included performing procedures to assess the risks of material misstatement of the consolidated 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 consolidated financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the consolidated financial statements. Our audit of internal control over financial reporting included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, and testing and evaluating the design and operating effectiveness of internal control based on the assessed risk. Our audits also included performing such other procedures as we considered necessary in the circumstances. We believe that our audits provide a reasonable basis for our opinions.

Definition and Limitations of Internal Control Over Financial Reporting

A company’s internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. A company’s internal control over financial reporting includes those policies and procedures that (1) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company; (2) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of the company are being made only in accordance with authorizations of management and directors of the company; and (3) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company’s 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. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

Critical Audit Matters

The critical audit matter communicated below are matters arising from the current period audit of the consolidated financial statements that were communicated or required to be communicated to the audit committee and that: (1) relates to accounts or disclosures that are material to the consolidated financial statements and (2) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters does not alter in any way our opinion on the consolidated financial statements, taken as a whole, and we are not, by communicating the critical audit matters below, providing separate opinions on the critical audit matters or on the accounts or disclosures to which they relate.

Sufficiency of audit evidence over revenues from subscription services and related usage

As discussed in Note 1 to the consolidated financial statements, the Company charges customers subscription fees, usually billed on a monthly basis, for access to the Company’s Intelligent CX Platform. For the year ended December 31, 2024, the Company recorded $1,041.9 million of revenue. The subscription fees are primarily based on the number of licenses, as on a consumption or capacity basis for the Company’s Artificial Intelligence solutions. Licenses are defined as the maximum number to named agents allowed to concurrently access the Intelligent CX Platform. The majority of the Company’s customers purchase both subscriptions and related telephony usage. The related usage fees are based on the volume of minutes used for inbound and outbound customer interactions. There are high volumes of subscription and related usage transactions processed across multiple information technology (IT) systems.

We identified the evaluation of the sufficiency of audit evidence over revenue from subscription services and related usage as a critical audit matter. Revenues from subscription services and related usage involved a high volume of automated transactions dependent on the Company’s IT systems. Therefore, our audit procedures required the involvement of IT professionals and auditor judgment was required to determine the nature and extent of audit evidence obtained and evaluate the results of the procedures.

The following are the primary procedures we performed to address this critical audit matter. We involved IT professionals with specialized skills and knowledge, who assisted in evaluating the design and testing the operating effectiveness of certain internal controls related to the Company’s revenue process. This included controls related to the capture and flow of subscription and related usage transactional information through the Company’s IT systems. We placed test calls and observed that call attributes such as duration and type of service were captured in the relevant IT systems. We assessed the recorded revenue by comparing total cash received during the year, adjusted for reconciling items, to the revenue recognized. Such assessment also evaluated the relevance and reliability of reconciling items to underlying documentation, including the changes in accounts receivable and deferred revenue. We evaluated the sufficiency of audit evidence obtained by assessing the results of procedures performed, including the appropriateness of the nature and extent of such evidence.

Accounting for the repurchase of 2025 convertible senior notes

As discussed in Note 6 to the consolidated financial statements, on March 1, 2024, the Company used part of the net proceeds from the issuance of the 2029 convertible senior notes to repurchase approximately $313.1 million aggregate principal amount of the outstanding 2025 convertible senior notes (the Repurchase Transaction). The Repurchase Transaction was accounted for as a debt extinguishment. As a result, the Company recorded an extinguishment gain of approximately $6.6 million in Other income (expense), net in the Company’s consolidated statements of operations and comprehensive loss.

We identified the evaluation of the accounting for the Repurchase Transaction as a critical audit matter. A high degree of subjective auditor judgment was required to evaluate the appropriate accounting guidance for the Repurchase Transaction, specifically the technical assessment of the accounting for the debt extinguishment.

The following are the primary procedures we performed to address this critical audit matter. We evaluated the design and tested the operating effectiveness of certain internal controls related to the Company’s debt process, including a control related to the Company’s evaluation of the appropriate accounting guidance and technical accounting assessment. We evaluated the technical accounting assessment of the debt extinguishment by (1) obtaining and inspecting the underlying agreements, (2) evaluating the settlement price of the 2025 convertible senior notes on the date of the Repurchase Transaction by comparing the settlement price to the conversion price of the 2025 convertible senior notes, the conversion price to the trading price of the 2025 convertible senior notes, and the conversion price to the Company’s stock price, and (3) assessing whether there were any changes to conversion privileges.

/s/KPMG LLP

We have served as the Company’s auditor since 2012.

Santa Clara, California

February 20, 2025