Description of Business and Summary of Significant Accounting Policies	6 Months Ended
Jun. 30, 2026
Accounting Policies [Abstract]
Description of Business and Summary of Significant Accounting Policies	Description of Business and Summary of Significant Accounting Policies Five9, Inc. and its wholly-owned subsidiaries (the “Company”) is a provider of cloud software for contact centers. The Company was incorporated in Delaware in 2001 and is headquartered in San Ramon, California. In addition to the United States, the Company has offices in Europe, Asia and Australia, which primarily provide research, development, sales, marketing, and customer support services. Basis of Presentation The accompanying condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. Therefore, these condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2025. In the opinion of management, the condensed consolidated financial statements reflect all adjustments, which are normal and recurring in nature, necessary for fair financial statement presentation. All intercompany transactions and balances have been eliminated in consolidation. Use of Estimates The preparation of condensed consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements, including accompanying notes, and the reported amounts of revenue and expenses during the reporting period. The significant estimates made by management affect revenue and related reserves, as well as the fair value of assets acquired and liabilities assumed through business combinations and the fair value of the performance-based restricted stock units ("PRSUs"). Management periodically evaluates such estimates and they are adjusted prospectively based upon such periodic evaluation. Actual results could differ from those estimates. Significant Accounting Policies There have been no material changes from the significant accounting policies previously disclosed in Part II, Item 8, of the Company's Annual Report on Form 10-K for the fiscal year ended December 31, 2025 as filed with the SEC on February 20, 2026. Recently Adopted Accounting Pronouncements In July 2025, the FASB issued ASU 2025-05, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses for Accounts Receivable and Contract Assets. The ASU provides a practical expedient to assume that conditions as of the balance sheet date remain unchanged over the life of the asset when estimating expected credit losses for current accounts receivable and current contract assets arising from transactions accounted for under Topic 606. This guidance is effective for reporting periods beginning after December 15, 2025, with early adoption permitted. The Company's adoption of ASU 2025-05 electing the practical expedient method did not have a material impact on its financial position and results of operations. In November 2024, the FASB issued ASU 2024-04, Debt with Conversion and Other Options (Subtopic 470-20), which clarifies the requirements for determining whether certain settlements of convertible debt instruments should be accounted for as an induced conversion. The ASU is effective for annual and interim reporting periods beginning after December 15, 2025. Early adoption is permitted for entities that have implemented ASU 2020-06, with the option to apply the guidance prospectively or retrospectively. The Company's adoption of ASU 2024-04 on a prospective basis did not have an impact on its financial position and results of operations. Recent Accounting Pronouncements Not Yet Effective In November 2024, the FASB issued ASU 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40), and in January 2025, the FASB issued ASU 2025-01, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Clarifying the Effective Date, which clarified the effective date of ASU 2024-03. This ASU is intended to improve the decision-usefulness of expense information on public companies’ income statements through disaggregation of relevant expense captions in the notes to the financial statements. The guidance, as clarified by ASU 2025-01, is effective for annual reporting periods beginning after December 15, 2026, and interim periods within annual reporting periods beginning after December 15, 2027, with early adoption permitted. The Company is currently assessing the impact of this ASU on its consolidated financial statements and related disclosures. In September 2025, the FASB issued ASU 2025-06, Intangibles - Goodwill and Other-Internal-Use Software (Subtopic 350-40): Targeted Improvements to the Accounting for Internal-Use Software. The amendments are intended to modernize the recognition and capitalization framework to reflect current software development practices, including iterative and agile methodologies, by removing references to development project stages. It requires that an entity capitalize software costs when both of the following occur: (1) management has authorized and committed to funding the software project and (2) it is probable that the project will be completed and the software will be used to perform the function intended. The amendments in ASU 2025-06 are effective for annual reporting periods beginning after December 15, 2027, and interim reporting periods within those annual reporting periods. Early adoption is permitted as of the beginning of an annual reporting period. The Company is currently assessing the impact of this ASU on its consolidated financial statements and related disclosures. In December 2025, the FASB issued ASU 2025-11, Interim Reporting (Topic 270) Narrow Scope Improvements, which is intended to clarify the guidance in ASC 270. Under the amendments, an entity is subject to ASC 270 if it provides interim financial statements and notes in accordance with GAAP. ASU 2025-11 also addresses the form and content of such financial statements, adds lists to ASC 270 of the interim disclosures required by all other codification topics, and establishes a principle under which an entity must disclose events since the end of the last annual reporting period that have a material impact on the entity. ASU 2025-11 is effective for interim reporting periods within annual reporting periods beginning after December 15, 2027. Early adoption is permitted. The Company is currently assessing the impact of this ASU on its consolidated financial statements and related disclosures. In May 2026, the FASB issued ASU 2026-02, Environmental Credits and Environmental Credit Obligations (Topic 818). This ASU provides recognition, measurement, presentation and disclosure requirements for environmental credits and related environmental credit obligations. This guidance is effective for reporting periods beginning after December 15, 2027, with early adoption permitted. The Company is currently assessing the impact of this ASU on its consolidated financial statements and related disclosures.

Five9, Inc. and its wholly-owned subsidiaries (the “Company”) is a provider of cloud software for contact centers. The Company was incorporated in Delaware in 2001 and is headquartered in San Ramon, California. In addition to the United States, the Company has offices in Europe, Asia and Australia, which primarily provide research, development, sales, marketing, and customer support services.

The accompanying condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. Therefore, these condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2025. In the opinion of management, the condensed consolidated financial statements reflect all adjustments, which are normal and recurring in nature, necessary for fair financial statement presentation. All intercompany transactions and balances have been eliminated in consolidation.

The preparation of condensed consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements, including accompanying notes, and the reported amounts of revenue and expenses during the reporting period. The significant estimates made by management affect revenue and related reserves, as well as the fair value of assets acquired and liabilities assumed through business combinations and the fair value of the performance-based restricted stock units ("PRSUs"). Management periodically evaluates such estimates and they are adjusted prospectively based upon such periodic evaluation. Actual results could differ from those estimates.

There have been no material changes from the significant accounting policies previously disclosed in Part II, Item 8, of the Company's Annual Report on Form 10-K for the fiscal year ended December 31, 2025 as filed with the SEC on February 20, 2026.

In July 2025, the FASB issued ASU 2025-05, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses for Accounts Receivable and Contract Assets. The ASU provides a practical expedient to assume that conditions as of the balance sheet date remain unchanged over the life of the asset when estimating expected credit losses for current accounts receivable and current contract assets arising from transactions accounted for under Topic 606. This guidance is effective for reporting periods beginning after December 15, 2025, with early adoption permitted. The Company's adoption of ASU 2025-05 electing the practical expedient method did not have a material impact on its financial position and results of operations.

In November 2024, the FASB issued ASU 2024-04, Debt with Conversion and Other Options (Subtopic 470-20), which clarifies the requirements for determining whether certain settlements of convertible debt instruments should be accounted for as an induced conversion. The ASU is effective for annual and interim reporting periods beginning after December 15, 2025. Early adoption is permitted for entities that have implemented ASU 2020-06, with the option to apply the guidance prospectively or retrospectively. The Company's adoption of ASU 2024-04 on a prospective basis did not have an impact on its financial position and results of operations.

In November 2024, the FASB issued ASU 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40), and in January 2025, the FASB issued ASU 2025-01, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Clarifying the Effective Date, which clarified the effective date of ASU 2024-03. This ASU is intended to improve

the decision-usefulness of expense information on public companies’ income statements through disaggregation of relevant expense captions in the notes to the financial statements. The guidance, as clarified by ASU 2025-01, is effective for annual reporting periods beginning after December 15, 2026, and interim periods within annual reporting periods beginning after December 15, 2027, with early adoption permitted. The Company is currently assessing the impact of this ASU on its consolidated financial statements and related disclosures.

In September 2025, the FASB issued ASU 2025-06, Intangibles - Goodwill and Other-Internal-Use Software (Subtopic 350-40): Targeted Improvements to the Accounting for Internal-Use Software. The amendments are intended to modernize the recognition and capitalization framework to reflect current software development practices, including iterative and agile methodologies, by removing references to development project stages. It requires that an entity capitalize software costs when both of the following occur: (1) management has authorized and committed to funding the software project and (2) it is probable that the project will be completed and the software will be used to perform the function intended. The amendments in ASU 2025-06 are effective for annual reporting periods beginning after December 15, 2027, and interim reporting periods within those annual reporting periods. Early adoption is permitted as of the beginning of an annual reporting period. The Company is currently assessing the impact of this ASU on its consolidated financial statements and related disclosures.

In December 2025, the FASB issued ASU 2025-11, Interim Reporting (Topic 270) Narrow Scope Improvements, which is intended to clarify the guidance in ASC 270. Under the amendments, an entity is subject to ASC 270 if it provides interim financial statements and notes in accordance with GAAP. ASU 2025-11 also addresses the form and content of such financial statements, adds lists to ASC 270 of the interim disclosures required by all other codification topics, and establishes a principle under which an entity must disclose events since the end of the last annual reporting period that have a material impact on the entity. ASU 2025-11 is effective for interim reporting periods within annual reporting periods beginning after December 15, 2027. Early adoption is permitted. The Company is currently assessing the impact of this ASU on its consolidated financial statements and related disclosures.

In May 2026, the FASB issued ASU 2026-02, Environmental Credits and Environmental Credit Obligations (Topic 818). This ASU provides recognition, measurement, presentation and disclosure requirements for environmental credits and related environmental credit obligations. This guidance is effective for reporting periods beginning after December 15, 2027, with early adoption permitted. The Company is currently assessing the impact of this ASU on its consolidated financial statements and related disclosures.