Commitments and Contingencies	9 Months Ended
Sep. 30, 2026
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Commitments The Company’s principal commitments consist of future payment obligations under its convertible senior notes, finance leases to finance data centers and other computer and networking equipment, operating leases for office facilities, cloud services and software and maintenance agreements, and agreements with third parties to provide co-location hosting and telecommunication services. These commitments as of December 31, 2025 are disclosed in the Company’s Annual Report on Form 10-K for the year ended December 31, 2025, and material updates to these commitments during the nine months ended September 30, 2026 are disclosed herein, including in this Note 10 and in Note 12. As of September 30, 2026, the Company’s commitments under various co-location hosting and telecommunication usage service agreements totaled $15.2 million for terms ranging up to approximately five years. These agreements require the Company to make payments over the service term in exchange for certain network services. As of September 30, 2026, the Company had outstanding cloud services and software and maintenance agreement commitments totaling $105.8 million, of which $47.4 million is expected to be purchased in 2027, and the remaining $58.4 million is expected to be purchased in 2028. During the first nine months of 2026, the Company executed a reseller agreement with a total commitment of $9.0 million, a term from March 31, 2026 to March 31, 2027, with a total remaining commitment of $0.5 million as of September 30, 2026. During the first nine months of 2026, the Company entered into a $53.9 million five-year agreement for data center support and maintenance services, which was financed through a non-interest bearing financing arrangement. In accordance with ASC 835-30, the financing arrangement was recorded as a liability at its present value of $48.3 million using an imputed interest rate. The Company is obligated to make five installment payments of $10.8 million annually, with the first payment made upon execution of the agreement in March 2026, and the remaining four annual payments due from March 2027 through March 2030. The current and long-term portions of this obligation were $10.8 million and $28.0 million, respectively, as of September 30, 2026. As of September 30, 2026, $747.5 million of aggregate principal of the 2029 convertible senior notes was outstanding, with a maturity date of March 15, 2029. See Note 6 for more information concerning the convertible senior notes. Legal Matters The Company is involved in various legal and regulatory matters arising in the normal course of business. In management’s opinion, resolution of these matters is not expected to have a material impact on the Company’s consolidated results of operations, cash flows, or its financial position. However, due to the uncertain nature of legal matters, an unfavorable resolution of a matter could materially affect the Company’s future consolidated results of operations, cash flows or financial position in a particular period. The Company expenses legal fees as incurred. The Company is currently party to the following actions: On December 4, 2024, a purported holder of the Company’s securities filed a putative class action complaint against the Company, its then-current Chief Executive Officer, and its then-current Chief Financial Officer in the United States District Court for the Northern District of California alleging violations of Section 10(b) and 20(a) of the Securities Exchange Act of 1934 and Rule 10b-5, promulgated thereunder, based on alleged false and/or misleading statements or omissions regarding the Company and its business and seeking unspecified damages on behalf of all persons and entities (subject to specified exceptions) that purchased or otherwise acquired the Company’s securities, including call options, from June 4, 2024, through the close of trading on August 8, 2024 (the "Securities Action"). On February 3, 2025, Lucid Alternative Fund, LP moved to be appointed lead plaintiff of this action pursuant to the Private Securities Litigation Reform Act of 1995. On March 18, 2025, the court appointed Lucid Alternative Fund, LP as lead plaintiff and approved lead plaintiff’s selection of lead counsel. Per the court’s subsequent order on March 27, 2025, Lucid Alternative Fund, LP filed an amended complaint on May 30, 2025. The Company moved to dismiss the amended complaint on July 29, 2025, and the court took the motion under submission after oral argument on December 18, 2025. On February 23, 2026, the court granted in part and denied in part Defendants’ motion to dismiss. On October 29, 2026, the parties signed a binding term sheet to settle the Securities Action (the "Securities Action Term Sheet") following negotiations facilitated by a mediator. The Securities Action Term Sheet calls for the parties to prepare and execute a definitive stipulation of settlement (the "Securities Action Stipulation of Settlement") that will provide for the complete resolution, compromise, and settlement of the Securities Action in exchange for a payment of $11.6 million by the Company’s insurers. The settlement of the Securities Action is conditioned on, among other things, the finalization of the Securities Action Stipulation of Settlement; timely funding of the Securities Action settlement amount; preliminary approval of the Securities Action Stipulation of Settlement; and entry of a judgment approving the Securities Action Stipulation of Settlement. In connection with the settlement of the Securities Action, there will be no admission of liability by the Company or any defendants and the Company, the defendants, and related persons will receive a customary full release of all claims that were or could have been asserted. Three shareholder derivative actions related to the securities class action described above are pending in three jurisdictions. On March 18, 2025, a related shareholder derivative action was filed in the United States District Court for the Northern District of California on behalf of nominal defendant Five9, Inc. and against its directors and certain of its officers seeking to assert claims for breach of fiduciary duty, unjust enrichment, abuse of control, gross mismanagement, and waste of corporate assets, and for contribution under Sections 10(b) and 21D of the Securities Exchange Act of 1934. On February 27, 2026, a separate and related shareholder derivative action was filed again in the United States District Court for the Northern District of California on behalf of nominal defendant Five9, Inc. and against its directors and certain of its officers seeking to assert claims for breach of fiduciary duty, unjust enrichment, abuse of control, gross mismanagement, and waste of corporate assets, and for contribution under Sections 10(b) and 21D of the Securities Exchange Act of 1934. On March 9, 2026, all parties filed a stipulation with the court to consolidate the two derivative actions, which the court so ordered on March 17, 2026. On May 20, 2026, the court entered an order on the parties’ stipulation staying the derivative action. On March 24, 2026, a related shareholder derivative action was filed in the United States District Court for the District of Delaware on behalf of nominal defendant Five9, Inc. and against its directors and certain of its officers seeking to assert claims for breaches of fiduciary duties, gross mismanagement, waste of corporate assets, unjust enrichment, and violation of Section 14(a) of the Securities Exchange Act of 1934. On April 15, 2026, the court entered an order on the parties' stipulation staying the derivative action. On October 1, 2026, a related shareholder derivative action was filed in the Delaware Court of Chancery on behalf of nominal defendant Five9, Inc. and against its directors and certain of its officers seeking to assert claims for breach of fiduciary duty, unjust enrichment, and waste of corporate assets. On October 19, 2026, the court entered an order on the parties’ stipulation staying the derivative action. Indemnification Agreements In the ordinary course of business, the Company enters into agreements of varying scope and terms pursuant to which it agrees to indemnify customers, vendors, lessors, business partners and other parties with respect to certain matters, including losses arising out of breach of such agreements, including breach of security, services to be provided by the Company or from intellectual property infringement claims made by third parties. The Company has received indemnification demands, and will likely continue to receive demands, from customers regarding its intellectual property indemnification obligations under these contracts. In addition, the Company has entered into indemnification agreements with its directors, officers and certain employees that requires it, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors, officers or employees. There are no claims that the Company is aware of that could have a material effect on the consolidated balance sheets, consolidated statements of operations and comprehensive income (loss), or consolidated statements of cash flows.

Commitments and Contingencies

9 Months Ended

Sep. 30, 2026

Commitments and Contingencies Disclosure [Abstract]

Commitments

The Company’s principal commitments consist of future payment obligations under its convertible senior notes, finance leases to finance data centers and other computer and networking equipment, operating leases for office facilities, cloud services and software and maintenance agreements, and agreements with third parties to

provide co-location hosting and telecommunication services. These commitments as of December 31, 2025 are disclosed in the Company’s Annual Report on Form 10-K for the year ended December 31, 2025, and material updates to these commitments during the nine months ended September 30, 2026 are disclosed herein, including in this Note 10 and in Note 12.

As of September 30, 2026, the Company’s commitments under various co-location hosting and telecommunication usage service agreements totaled $15.2 million for terms ranging up to approximately five years. These agreements require the Company to make payments over the service term in exchange for certain network services.

As of September 30, 2026, the Company had outstanding cloud services and software and maintenance agreement commitments totaling $105.8 million, of which $47.4 million is expected to be purchased in 2027, and the remaining $58.4 million is expected to be purchased in 2028.

During the first nine months of 2026, the Company executed a reseller agreement with a total commitment of $9.0 million, a term from March 31, 2026 to March 31, 2027, with a total remaining commitment of $0.5 million as of September 30, 2026.

During the first nine months of 2026, the Company entered into a $53.9 million five-year agreement for data center support and maintenance services, which was financed through a non-interest bearing financing arrangement. In accordance with ASC 835-30, the financing arrangement was recorded as a liability at its present value of $48.3 million using an imputed interest rate. The Company is obligated to make five installment payments of $10.8 million annually, with the first payment made upon execution of the agreement in March 2026, and the remaining four annual payments due from March 2027 through March 2030. The current and long-term portions of this obligation were $10.8 million and $28.0 million, respectively, as of September 30, 2026.

As of September 30, 2026, $747.5 million of aggregate principal of the 2029 convertible senior notes was outstanding, with a maturity date of March 15, 2029. See Note 6 for more information concerning the convertible senior notes.

Legal Matters

The Company is involved in various legal and regulatory matters arising in the normal course of business. In management’s opinion, resolution of these matters is not expected to have a material impact on the Company’s consolidated results of operations, cash flows, or its financial position. However, due to the uncertain nature of legal matters, an unfavorable resolution of a matter could materially affect the Company’s future consolidated results of operations, cash flows or financial position in a particular period. The Company expenses legal fees as incurred. The Company is currently party to the following actions:

On December 4, 2024, a purported holder of the Company’s securities filed a putative class action complaint against the Company, its then-current Chief Executive Officer, and its then-current Chief Financial Officer in the United States District Court for the Northern District of California alleging violations of Section 10(b) and 20(a) of the Securities Exchange Act of 1934 and Rule 10b-5, promulgated thereunder, based on alleged false and/or misleading statements or omissions regarding the Company and its business and seeking unspecified damages on behalf of all persons and entities (subject to specified exceptions) that purchased or otherwise acquired the Company’s securities, including call options, from June 4, 2024, through the close of trading on August 8, 2024 (the "Securities Action"). On February 3, 2025, Lucid Alternative Fund, LP moved to be appointed lead plaintiff of this action pursuant to the Private Securities Litigation Reform Act of 1995. On March 18, 2025, the court appointed Lucid Alternative Fund, LP as lead plaintiff and approved lead plaintiff’s selection of lead counsel. Per the court’s subsequent order on March 27, 2025, Lucid Alternative Fund, LP filed an amended complaint on May 30, 2025. The Company moved to dismiss the amended complaint on July 29, 2025, and the court took the motion under submission after oral argument on December 18, 2025. On February 23, 2026, the court granted in part and denied in part Defendants’ motion to dismiss. On October 29, 2026, the parties signed a binding term sheet to settle the Securities Action (the "Securities Action Term Sheet") following negotiations facilitated by a mediator. The Securities Action Term Sheet calls for the parties to prepare and execute a definitive stipulation of settlement (the "Securities Action Stipulation of Settlement") that will provide for the complete resolution, compromise, and settlement of the Securities Action in exchange for a payment of $11.6 million by the Company’s insurers. The settlement of the Securities Action is conditioned on, among other things, the finalization of the Securities Action Stipulation of Settlement; timely funding of the Securities Action settlement amount; preliminary approval of the Securities Action Stipulation of Settlement; and entry of a judgment approving the Securities Action Stipulation of

Settlement. In connection with the settlement of the Securities Action, there will be no admission of liability by the Company or any defendants and the Company, the defendants, and related persons will receive a customary full release of all claims that were or could have been asserted.

Three shareholder derivative actions related to the securities class action described above are pending in three jurisdictions. On March 18, 2025, a related shareholder derivative action was filed in the United States District Court for the Northern District of California on behalf of nominal defendant Five9, Inc. and against its directors and certain of its officers seeking to assert claims for breach of fiduciary duty, unjust enrichment, abuse of control, gross mismanagement, and waste of corporate assets, and for contribution under Sections 10(b) and 21D of the Securities Exchange Act of 1934. On February 27, 2026, a separate and related shareholder derivative action was filed again in the United States District Court for the Northern District of California on behalf of nominal defendant Five9, Inc. and against its directors and certain of its officers seeking to assert claims for breach of fiduciary duty, unjust enrichment, abuse of control, gross mismanagement, and waste of corporate assets, and for contribution under Sections 10(b) and 21D of the Securities Exchange Act of 1934. On March 9, 2026, all parties filed a stipulation with the court to consolidate the two derivative actions, which the court so ordered on March 17, 2026. On May 20, 2026, the court entered an order on the parties’ stipulation staying the derivative action.

On March 24, 2026, a related shareholder derivative action was filed in the United States District Court for the District of Delaware on behalf of nominal defendant Five9, Inc. and against its directors and certain of its officers seeking to assert claims for breaches of fiduciary duties, gross mismanagement, waste of corporate assets, unjust enrichment, and violation of Section 14(a) of the Securities Exchange Act of 1934. On April 15, 2026, the court entered an order on the parties' stipulation staying the derivative action.

On October 1, 2026, a related shareholder derivative action was filed in the Delaware Court of Chancery on behalf of nominal defendant Five9, Inc. and against its directors and certain of its officers seeking to assert claims for breach of fiduciary duty, unjust enrichment, and waste of corporate assets. On October 19, 2026, the court entered an order on the parties’ stipulation staying the derivative action.

Indemnification Agreements

In the ordinary course of business, the Company enters into agreements of varying scope and terms pursuant to which it agrees to indemnify customers, vendors, lessors, business partners and other parties with respect to certain matters, including losses arising out of breach of such agreements, including breach of security, services to be provided by the Company or from intellectual property infringement claims made by third parties. The Company has received indemnification demands, and will likely continue to receive demands, from customers regarding its intellectual property indemnification obligations under these contracts. In addition, the Company has entered into indemnification agreements with its directors, officers and certain employees that requires it, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors, officers or employees. There are no claims that the Company is aware of that could have a material effect on the consolidated balance sheets, consolidated statements of operations and comprehensive income (loss), or consolidated statements of cash flows.