Exhibit 10.10

FIVE9, INC.

2014 EMPLOYEE STOCK PURCHASE PLAN

ADOPTED BY THE BOARD OF DIRECTORS: MARCH 6, 2014

APPROVED BY THE STOCKHOLDERS: MARCH 16, 2014

1. GENERAL; PURPOSE.

(a) The Plan provides a means by which Eligible Employees of the Company and certain Designated Companies may be given an opportunity to purchase shares of Common Stock. The Plan permits the Company to grant a series of Purchase Rights to Eligible Employees.

(b) The Company, by means of the Plan, seeks to retain the services of such Employees, to secure and retain the services of new Employees and to provide incentives for such persons to exert maximum efforts for the success of the Company and its Related Corporations.

(c) This Plan includes two components: a 423 Component and a Non-423 Component. It is the intention of the Company to have the 423 Component qualify as an Employee Stock Purchase Plan. The provisions of the 423 Component, accordingly, will be construed in a manner that is consistent with the requirements of Section 423. In addition, this Plan authorizes the grant of Purchase Rights under the Non-423 Component that does not meet the requirements of an Employee Stock Purchase Plan because of deviations necessary or advisable to permit or facilitate participation in the Plan by Employees who are foreign nationals or employed or located outside of the United States while complying with applicable foreign laws; such Purchase Rights will be granted pursuant to rules, procedures or sub-plans adopted by the Board designed to achieve these objectives for Eligible Employees and the Company and its Related Corporations. Except as otherwise provided herein or determined by the Board, the Non-423 Component will operate and be administered in the same manner as the 423 Component. In addition, under the 423 Component, the Company may make separate Offerings which vary in terms (although not inconsistent with the provisions of the Plan and not inconsistent with the requirements of an Employee Stock Purchase Plan), and the Company will designate which Designated Company is participating in each separate Offering.

(d) If a Participant transfers employment from the Company or any Designated 423 Corporation participating in the 423 Component to a Designated Non-423 Corporation participating in the Non-423 Component, he or she will immediately cease to participate in the 423 Component; however, any Contributions made for the Purchase Period in which such transfer occurs will be transferred to the Non-423 Component, and such Participant will immediately join the then-current Offering under the Non-423 Component on the same terms and conditions in effect for his or her participation in the Plan, except for such modifications as may be required by or appropriate under applicable law. If a Participant transfers employment from a Designated Non-423 Corporation participating in the Non-423 Component to the Company or any Designated 423 Corporation participating in the 423 Component, he or she will remain a Participant in the Non-423 Component until the earlier of (i) the end of the current Offering under the Non-423 Component, or (ii) the Offering Date of the

first Offering in which he or she participates following such transfer. If a Participant transfers employment to either a Related Corporation or an Affiliate that is not a Designated Company, he or she will immediately cease to participate in the ongoing Offering, and his or her accumulated, unused Contributions will be returned as soon as possible.

2. ADMINISTRATION.

(a) The Board will administer the Plan unless and until the Board delegates administration of the Plan to a Committee or Committees, as provided in Section 2(c).

(b) The Board will have the power, subject to, and within the limitations of, the express provisions of the Plan:

i. To determine how and when Purchase Rights will be granted and the provisions of each Offering (which need not be identical), including which Designated 423 Corporations and Designated Non-423 Corporations will participate in the 423 Component or the Non-423 Component.

ii. To designate from time to time which Related Corporations of the Company will be eligible to participate in the Plan as Designated 423 Corporations and Designated Non-423 Corporations and which Affiliates will be eligible to participate in the Plan as Designated Non-423 Corporations and also to designate which Designated Companies will participate in each separate Offering (to the extent the Company makes separate Offerings).

iii. To construe and interpret the Plan and Purchase Rights and to establish, amend and revoke rules and regulations for the Plan’s administration. The Board, in the exercise of this power, may correct any defect, omission or inconsistency in the Plan, in a manner and to the extent it deems necessary or expedient to make the Plan fully effective.

iv. To settle all controversies regarding the Plan and Purchase Rights granted under the Plan.

v. To suspend or terminate the Plan at any time as provided in Section 12.

vi. To amend the Plan at any time as provided in Section 12.

vii. Generally, to exercise such powers and to perform such acts as it deems necessary or expedient to promote the best interests of the Company and its Related Corporations and to carry out the intent that the 423 Component be treated as an Employee Stock Purchase Plan.

viii. To adopt such procedures and sub-plans as are necessary or appropriate to permit or facilitate participation in the Plan by Employees who are foreign nationals or employed or located outside the United States. Without limiting the generality of, but consistent with, the foregoing, the Board specifically is authorized to adopt rules, procedures and sub-plans, which, for purposes of the Non-423 Component, may be outside the scope of Section 423 regarding, without limitation, eligibility to participate in the Plan, handling and

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making of Contributions, establishment of bank or trust accounts to hold Contributions, payment of interest, conversion of local currency, obligations to pay payroll tax, determination of beneficiary designation requirements, withholding procedures and handling of share issuances, which may vary according to local requirements or practices.

(c) The Board may delegate some or all of the administration of the Plan to a Committee or Committees. If administration is delegated to a Committee, the Committee will have, in connection with the administration of the Plan, the powers theretofore possessed by the Board that have been delegated to the Committee, including the power to delegate to a subcommittee any of the administrative powers the Committee is authorized to exercise (and references in this Plan to the Board will thereafter be to the Committee or subcommittee), subject, however, to such resolutions, not inconsistent with the provisions of the Plan, as may be adopted from time to time by the Board. The Board may retain the authority to concurrently administer the Plan with the Committee and may, at any time, revest in the Board some or all of the powers previously delegated. The Board will have the final power to determine all questions of policy and expediency that may arise in the administration of the Plan.

(d) All determinations, interpretations and constructions made by the Board in good faith will not be subject to review by any person and will be final, binding and conclusive on all persons.

3. SHARES OF COMMON STOCK SUBJECT TO THE PLAN.

(a) Subject to the provisions of Section 11(a) relating to Capitalization Adjustments, the maximum number of shares of Common Stock that may be issued under the Plan will not exceed 3,520,000 shares of Common Stock1, plus the number of shares that are automatically added on January 1 of each year for a period of up to ten (10) years, commencing on the first January 1 following the IPO Date and ending on January 1, 2024, in an amount equal to the lesser of (i) 1% of the total number of shares of Common Stock outstanding on December 31 of the preceding calendar year, or (ii) 4,000,000 shares of Common Stock2. Notwithstanding the foregoing, the Board may act prior to the first day of any calendar year to provide that there will be no January 1 increase in the share reserve for such calendar year or that the increase in the share reserve for such calendar year will be a lesser number of shares of Common Stock than would otherwise occur pursuant to the preceding sentence.

(b) If any Purchase Right granted under the Plan terminates without having been exercised in full, the shares of Common Stock not purchased under such Purchase Right will again become available for issuance under the Plan.

(c) The stock purchasable under the Plan will be shares of authorized but unissued or reacquired Common Stock, including shares repurchased by the Company on the open market.

1 | Subject to any stock split that occurs in connection with the IPO.

2 | Subject to any stock split that occurs in connection with the IPO.

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4. GRANT OF PURCHASE RIGHTS; OFFERING.

(a) The Board may from time to time grant or provide for the grant of Purchase Rights to Eligible Employees under an Offering on Offering Dates selected by the Board. Each Offering will be in such form and will contain such terms and conditions as the Board will deem appropriate and with respect to the 423 Component, will comply with the requirement of Section 423(b)(5) of the Code that all Employees granted Purchase Rights will have the same rights and privileges. The provisions of separate Offerings need not be identical, but each Offering will include (through incorporation of the provisions of this Plan, by reference in the applicable Offering Document or otherwise) the period during which the Offering will be effective, which period will not exceed twenty-seven (27) months beginning with the Offering Date, and the substance of the provisions contained in Sections 5 through 8, inclusive.

(b) If a Participant has more than one Purchase Right outstanding under the Plan, unless he or she otherwise indicates in forms delivered to the Company: (i) each form will apply to all of his or her Purchase Rights under the Plan, and (ii) a Purchase Right with a lower exercise price (or an earlier-granted Purchase Right, if different Purchase Rights have identical exercise prices) will be exercised to the fullest possible extent before a Purchase Right with a higher exercise price (or a later-granted Purchase Right if different Purchase Rights have identical exercise prices) will be exercised.

(c) The Board will have the discretion to structure an Offering so that if the Fair Market Value of the shares of Common Stock on the first Trading Day of a new Purchase Period within that Offering is less than or equal to the Fair Market Value of the shares of Common Stock on the Offering Date, then (i) that Offering will terminate immediately as of that first Trading Day, and (ii) the Participants in such terminated Offering will be automatically enrolled in a new Offering beginning on the first Trading Day of such new Purchase Period.

5. ELIGIBILITY.

(a) Purchase Rights may be granted only to Employees of the Company or, as the Board may designate in accordance with Section 2(b), to Employees of a Related Corporation or an Affiliate. Except as provided in Section 5(b), an Employee will not be eligible to be granted Purchase Rights unless, on the Offering Date, the Employee has been in the employ of the Company, a Related Corporation or an Affiliate, as the case may be, for such continuous period preceding such Offering Date as the Board may require, but in no event will the required period of continuous employment be equal to or greater than two (2) years. In addition, the Board may (unless prohibited by law) provide that no Employee will be eligible to be granted Purchase Rights under the Plan unless, on the Offering Date, such Employee’s customary employment with the Company, a Related Corporation or an Affiliate is more than twenty (20) hours per week and more than five (5) months per calendar year or such other criteria as the Board may determine consistent with Section 423.

(b) The Board may provide that each person who, during the course of an Offering, first becomes an Eligible Employee will, on or after the day on which such person becomes an Eligible Employee, receive a Purchase Right under that Offering, which Purchase Right will thereafter be deemed to be a part of that Offering. Such Purchase Right will have the same characteristics as any Purchase Rights originally granted under that Offering, as described herein, except that:

i. the date on which such Purchase Right is granted will be the “Offering Date” of such Purchase Right for all purposes, including determination of the exercise price of such Purchase Right;

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ii. the period of the Offering with respect to such Purchase Right will begin on its Offering Date and end coincident with the end of the original Offering; and

iii. the Board may provide that if such person first becomes an Eligible Employee within a specified period of time before the end of the Offering, he or she will not receive any Purchase Right under that Offering.

(c) No Employee will be eligible for the grant of any Purchase Rights if, immediately after any such Purchase Rights are granted, such Employee owns stock possessing five percent (5%) or more of the total combined voting power or value of all classes of stock of the Company or of any Related Corporation (unless otherwise required by law). For purposes of this Section 5(c), the rules of Section 424(d) of the Code will apply in determining the stock ownership of any Employee, and stock which such Employee may purchase under all outstanding Purchase Rights and options will be treated as stock owned by such Employee.

(d) As specified by Section 423(b)(8) of the Code, an Eligible Employee may be granted Purchase Rights only if such Purchase Rights, together with any other rights granted under all Employee Stock Purchase Plans of the Company and any Related Corporations, do not permit such Eligible Employee’s rights to purchase stock of the Company or any Related Corporation to accrue at a rate which exceeds twenty-five thousand dollars ($25,000) of Fair Market Value of such stock (determined at the time such rights are granted and which, with respect to the Plan, will be determined as of their respective Offering Dates) for each calendar year in which such rights are outstanding at any time.

(e) Officers of the Company and any Designated Company, if they are otherwise Eligible Employees, will be eligible to participate in Offerings under the Plan. Notwithstanding the foregoing, the Board may (unless prohibited by law) provide in an Offering that Employees who are highly compensated Employees within the meaning of Section 423(b)(4)(D) of the Code will not be eligible to participate.

6. PURCHASE RIGHTS; PURCHASE PRICE.

(a) On each Offering Date, each Eligible Employee will be granted a Purchase Right under the applicable Offering to purchase up to that number of shares of Common Stock purchasable either with a percentage or with a maximum dollar amount, as designated by the Board, but in either case not exceeding fifteen percent (15%) of such Employee’s eligible earnings (as defined by the Board in each Offering) during the period that begins on the Offering Date (or such other date as the Board determines for a particular Offering) and ends on the date stated in the Offering, which date will be no later than the end of the Offering.

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(b) The Board will establish one or more Purchase Dates during an Offering on which Purchase Rights granted for that Offering will be exercised and shares of Common Stock will be purchased in accordance with such Offering.

(c) In connection with each Offering made under the Plan, the Board may specify (i) a maximum number of shares of Common Stock that may be purchased by any Participant on any Purchase Date during such Offering, (ii) a maximum aggregate number of shares of Common Stock that may be purchased by all Participants pursuant to such Offering, and/or (iii) a maximum aggregate number of shares of Common Stock that may be purchased by all Participants on any Purchase Date under the Offering. If the aggregate purchase of shares of Common Stock issuable on exercise of Purchase Rights granted under the Offering would exceed any such maximum aggregate number, then, in the absence of any Board action otherwise, a pro rata (based on each Participant’s accumulated Contributions) allocation of the shares of Common Stock available will be made in as nearly a uniform manner as will be practicable and equitable.

(d) The purchase price of shares of Common Stock acquired pursuant to Purchase Rights will be not less than the lesser of:

i. an amount equal to eighty-five (85%) of the Fair Market Value of the shares of Common Stock on the Offering Date; or

ii. an amount equal to eighty-five (85%) of the Fair Market Value of the shares of Common Stock on the applicable Purchase Date.

7. PARTICIPATION; WITHDRAWAL; TERMINATION.

(a) An Eligible Employee may elect to authorize payroll deductions as the means of making Contributions by completing and delivering to the Company, within the time specified in the Offering, an enrollment form provided by the Company. The enrollment form will specify the amount of Contributions (not to exceed the maximum amount specified by the Board). Each Participant’s Contributions will be credited to a bookkeeping account for such Participant under the Plan and will be deposited with the general funds of the Company except where applicable law requires that Contributions be deposited with a third party or otherwise segregated. If permitted in the Offering, a Participant may begin such Contributions with the first payroll occurring on or after the Offering Date (or, in the case of a payroll date that occurs after the end of the prior Offering but before the Offering Date of the next new Offering, Contributions from such payroll will be included in the new Offering). If permitted in the Offering, a Participant may thereafter reduce (including to zero) or increase his or her Contributions. If required under applicable law or if specifically provided in the Offering, in addition to or instead of making Contributions by payroll deductions, a Participant may make Contributions through the payment by cash, check or wire transfer prior to a Purchase Date, in the manner directed by the Company.

(b) During an Offering, a Participant may cease making Contributions and withdraw from the Offering by delivering to the Company a withdrawal form provided by the Company. The Company may impose a deadline before a Purchase Date for withdrawing. On

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such withdrawal, such Participant’s Purchase Right in that Offering will immediately terminate, and the Company will distribute to such Participant all of his or her accumulated but unused Contributions. A Participant’s withdrawal from that Offering will have no effect on his or her eligibility to participate in any other Offerings under the Plan, but the Participant will be required to deliver a new enrollment form to participate in future Offerings.

(c) Unless otherwise required by applicable law, Purchase Rights granted pursuant to any Offering under the Plan will terminate immediately if the Participant is either (i) no longer an Employee of a Designated Company for any reason or for no reason, or (ii) otherwise no longer eligible to participate. The Company will distribute to such individual all of his or her accumulated but unused Contributions.

(d) During a Participant’s lifetime, Purchase Rights will be exercisable only by such Participant. Purchase Rights are not transferable by a Participant, except by will, by the laws of descent and distribution or, if permitted by the Company, by a beneficiary designation as described in Section 10.

(e) The Company has no obligation to pay interest on Contributions, unless otherwise required by applicable law.

8. EXERCISE OF PURCHASE RIGHTS.

(a) On each Purchase Date, each Participant’s accumulated Contributions will be applied to the purchase of shares of Common Stock, up to the maximum number of shares of Common Stock permitted by the Plan and the applicable Offering, at the purchase price specified in the Offering. No fractional shares will be issued unless specifically provided for in the Offering.

(b) If any amount of accumulated Contributions remains in a Participant’s account after the purchase of shares of Common Stock on the final Purchase Date of an Offering and such remaining amount is less than the amount required to purchase one share of Common Stock, then such remaining amount will be held in such Participant’s account for the purchase of shares of Common Stock under the next Offering under the Plan, unless such Participant withdraws from or is not eligible to participate in such Offering, in which case such amount will be distributed to such Participant after the final Purchase Date, without interest (unless otherwise required by applicable law). If the amount of Contributions remaining in a Participant’s account after the purchase of shares of Common Stock on the final Purchase Date of an Offering is at least equal to the amount required to purchase one whole share of Common Stock, then such remaining amount will not roll over to the next Offering and will instead be distributed in full to such Participant after the final Purchase Date, without interest (unless otherwise required by applicable law).

(c) No Purchase Rights may be exercised to any extent unless the shares of Common Stock to be issued on such exercise under the Plan are covered by an effective registration statement pursuant to the U.S. Securities Act of 1933, as amended, and the Plan is in material compliance with all applicable laws. If on a Purchase Date the shares of Common Stock are not so registered or the Plan is not in such compliance, no Purchase Rights will be

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exercised on such Purchase Date, and the Purchase Date will be delayed until the shares of Common Stock are subject to such an effective registration statement and the Plan is in material compliance, except that the Purchase Date will in no event be more than twenty-seven (27) months from the Offering Date. If, on the Purchase Date, as delayed to the maximum extent permissible, the shares of Common Stock are not registered and the Plan is not in material compliance with all applicable laws, no Purchase Rights will be exercised and all accumulated but unused Contributions will be distributed to the Participants without interest (unless otherwise required under applicable law).

9. COVENANTS OF THE COMPANY.

To the extent practicable, the Company will seek to obtain from each federal, state, foreign or other regulatory commission or agency having jurisdiction over the Plan such authority as may be required to grant Purchase Rights and to issue and sell shares of Common Stock thereunder unless doing so would be an unreasonable cost to the Company compared to the potential benefit to Eligible Employees, which the Company will determine at its discretion. If, after commercially reasonable efforts, the Company is unable to obtain the authority that counsel for the Company deems necessary for the grant of Purchase Rights or the lawful issuance and sale of shares of Common Stock under the Plan (and at a commercially reasonable cost), the Company will be relieved from any liability for failure to grant Purchase Rights and/or to issue and sell shares of Common Stock on exercise of such Purchase Rights.

10. DESIGNATION OF BENEFICIARY.

(a) The Company may, but is not obligated to, permit a Participant to submit a form designating a beneficiary who will receive any shares of Common Stock and/or Contributions from the Participant’s account under the Plan if the Participant dies before such shares and/or Contributions are delivered to the Participant. The Company may, but is not obligated to, permit the Participant to change such designation of beneficiary. Any such designation and/or change must be on a form approved by the Company.

(b) If a Participant dies, and in the absence of a valid beneficiary designation, the Company will deliver any shares of Common Stock and/or Contributions to the executor or administrator of the estate of the Participant. If no executor or administrator has been appointed (to the knowledge of the Company), the Company, in its sole discretion, may deliver such shares of Common Stock and/or Contributions to the Participant’s spouse, dependents or relatives, or if no spouse, dependent or relative is known to the Company, then to such other person as the Company may designate.

11. ADJUSTMENTS ON CHANGES IN SHARES OF COMMON STOCK; CORPORATE TRANSACTIONS.

(a) On a Capitalization Adjustment, the Board will appropriately and proportionately adjust: (i) the class(es) and maximum number of securities subject to the Plan pursuant to Section 3(a), (ii) the class(es) and maximum number of securities by which the share reserve is to increase automatically each year pursuant to Section 3(a), (iii) the class(es) and number of securities subject to, and the purchase price applicable to, outstanding Offerings and

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Purchase Rights, and (iv) the class(es) and number of securities that are the subject of the purchase limits under each ongoing Offering. The Board will make these adjustments, and its determination will be final, binding and conclusive.

(b) On a Corporate Transaction, then: (i) any surviving corporation or acquiring corporation (or the surviving or acquiring corporation’s parent company) may assume or continue outstanding Purchase Rights or may substitute similar rights (including a right to acquire the same consideration paid to the stockholders in the Corporate Transaction) for outstanding Purchase Rights, or (ii) if any surviving or acquiring corporation (or its parent company) does not assume or continue such Purchase Rights or does not substitute similar rights for such Purchase Rights, then the Participants’ accumulated Contributions will be used to purchase shares of Common Stock within ten (10) business days prior to the Corporate Transaction under the outstanding Purchase Rights, and the Purchase Rights will terminate immediately after such purchase.

12. AMENDMENT, TERMINATION OR SUSPENSION OF THE PLAN.

(a) The Board may amend the Plan at any time and in any respect that the Board deems necessary or advisable. However, except as provided in Section 11(a) relating to Capitalization Adjustments, stockholder approval will be required for any amendment of the Plan for which stockholder approval is required by applicable law or listing requirements, including any amendment that (i) materially increases the number of shares of Common Stock available for issuance under the Plan, (ii) materially expands the class of individuals eligible to become Participants and receive Purchase Rights, (iii) materially increases the benefits accruing to Participants under the Plan or materially reduces the price at which shares of Common Stock may be purchased under the Plan, (iv) materially extends the term of the Plan, or (v) expands the types of awards available for issuance under the Plan, but in each of (i) through (v) above, only to the extent stockholder approval is required by applicable law or listing requirements.

(b) The Board may suspend or terminate the Plan at any time. No Purchase Rights may be granted under the Plan while the Plan is suspended or after it is terminated.

(c) Any benefits, privileges, entitlements and obligations under any outstanding Purchase Rights granted before an amendment, suspension or termination of the Plan will not be materially impaired by any such amendment, suspension or termination except (i) with the consent of the person to whom such Purchase Rights were granted, (ii) as necessary to comply with any laws, listing requirements or governmental regulations (including, without limitation, the provisions of Section 423 and the regulations and other interpretive guidance issued thereunder relating to Employee Stock Purchase Plans), including, without limitation, any such regulations or other guidance that may be issued or amended after the effective date of the Plan, as described in Section 14, or (iii) as necessary to obtain or maintain favorable tax, listing or regulatory treatment. To be clear, the Board may amend outstanding Purchase Rights without a Participant’s consent if such amendment is necessary to ensure that the Purchase Right and/or the Plan complies with the requirements of Section 423.

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13. SECTION 409A; TAX QUALIFICATION.

(a) Purchase Rights granted under the 423 Component are intended to be exempt from the application of Section 409A under Treasury Regulation Section 1.409A-1(b)(5)(ii). Purchase Rights granted under the Non-423 Component to U.S. taxpayers are intended to be exempt from the application of Section 409A under the short-term deferral exception, and any ambiguities will be construed and interpreted in accordance with such intent. Subject to Section 13(b), Purchase Rights granted to U.S. taxpayers under the Non-423 Component will be subject to such terms and conditions that will permit such Purchase Rights to satisfy the requirements of the short-term deferral exception available under Section 409A, including the requirement that the shares subject to a Purchase Right be delivered within the short-term deferral period. Subject to Section 13(b), in the case of a Participant who would otherwise be subject to Section 409A, to the extent the Board determines that a Purchase Right or the exercise, payment, settlement or deferral thereof is subject to Section 409A, the Purchase Right will be granted, exercised, paid, settled or deferred in a manner that will comply with Section 409A, including U.S. Department of Treasury regulations and other interpretive guidance issued thereunder, including, without limitation, any such regulations or other guidance that may be issued after the adoption of the Plan. Notwithstanding the foregoing, the Company will have no liability to a Participant or any other party if the Purchase Right that is intended to be exempt from or compliant with Section 409A is not so exempt or compliant or for any action taken by the Board with respect thereto.

(b) Although the Company may endeavor to (i) qualify a Purchase Right for favorable tax treatment under the laws of the United States or jurisdictions outside of the United States, or (ii) avoid adverse tax treatment (e.g., under Section 409A), the Company makes no representation to that effect and expressly disavows any covenant to maintain favorable or avoid unfavorable tax treatment, notwithstanding anything to the contrary in this Plan, including Section 13(a). The Company will be unconstrained in its corporate activities without regard to the potential negative tax impact on Participants under the Plan.

14. EFFECTIVE DATE OF PLAN.

The Plan will become effective on the IPO Date. No Purchase Rights will be exercised unless and until the Plan has been approved by the stockholders of the Company, which approval must be within twelve (12) months before or after the date the Plan is adopted (or if required under Section 12(a) above, materially amended) by the Board.

15. MISCELLANEOUS PROVISIONS.

(a) Proceeds from the sale of shares of Common Stock pursuant to Purchase Rights will constitute general funds of the Company.

(b) A Participant will not be deemed to be the holder of, or to have any of the rights of a holder with respect to, shares of Common Stock subject to Purchase Rights unless and until the Participant’s shares of Common Stock acquired on exercise of Purchase Rights are recorded in the books of the Company (or its transfer agent).

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(c) The Plan and Offering do not constitute an employment contract. Nothing in the Plan or in the Offering will in any way alter the at-will nature of a Participant’s employment, if applicable, or be deemed to create in any way whatsoever any obligation on the part of any Participant to continue in the employ of the Company, a Related Corporation or an Affiliate, or on the part of the Company, a Related Corporation or an Affiliate to continue the employment of a Participant.

(d) The provisions of the Plan will be governed by the laws of the State of California without resort to that state’s conflicts of laws rules.

(e) If any particular provision of the Plan is found to be invalid or otherwise unenforceable, such provision will not affect the other provisions of the Plan, but the Plan will be construed in all respects as if such invalid provision were omitted.

16. DEFINITIONS.

As used in the Plan, the following definitions will apply to the capitalized terms indicated below:

(a) “423 Component” means the part of the Plan, which excludes the Non-423 Component, pursuant to which Purchase Rights that satisfy the requirements for Employee Stock Purchase Plans may be granted to Eligible Employees.

(b) “Affiliate” means any branch or representative office of a Related Corporation, as determined by the Board, whether now or hereafter existing.

(c) “Board” means the Board of Directors of the Company.

(d) “Capitalization Adjustment” means any change that is made in, or other events that occur with respect to, the shares of Common Stock subject to the Plan or subject to any Purchase Right after the date on which the Plan becomes effective pursuant to Section 14 without the receipt of consideration by the Company through merger, consolidation, reorganization, recapitalization, reincorporation, stock dividend, dividend in property other than cash, large nonrecurring cash dividend, stock split, liquidating dividend, combination of shares, exchange of shares, change in corporate structure or other similar equity restructuring transaction, as that term is used in Financial Accounting Standards Board Accounting Standards Codification Topic 718 (or any successor thereto). Notwithstanding the foregoing, the conversion of any convertible securities of the Company will not be treated as a Capitalization Adjustment.

(e) “Code” means the U.S. Internal Revenue Code of 1986, as amended.

(f) “Committee” means a committee of one or more members of the Board to whom authority has been delegated by the Board.

(g) “Common Stock” means, as of the IPO Date, the common stock of the Company, having one vote per share.

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(h) “Company” means Five9, Inc., a Delaware corporation.

(i) “Contributions” means the payroll deductions and other additional payments specifically provided for in the Offering that a Participant contributes to fund the exercise of a Purchase Right. A Participant may make additional payments into his or her account if specifically provided for in the Offering and then only if the Participant has not already had the maximum permitted amount withheld during the Offering through payroll deductions.

(j) “Corporate Transaction” means the occurrence, in a single transaction or in a series of related transactions, of any one or more of the following events:

i. the consummation of a sale or other disposition of all or substantially all, as determined by the Board in its sole discretion, of the consolidated assets of the Company and its subsidiaries;

ii. the consummation of a sale or other disposition of more than fifty percent (50%) of the outstanding securities of the Company;

iii. the consummation of a merger, consolidation or similar transaction following which the Company is not the surviving corporation; or

iv. the consummation of a merger, consolidation or similar transaction following which the Company is the surviving corporation but the shares of Common Stock outstanding immediately preceding the merger, consolidation or similar transaction are converted or exchanged by virtue of the merger, consolidation or similar transaction into other property, whether in the form of securities, cash or otherwise.

To the extent required for compliance with Section 409A, in no event will an event be deemed a Corporate Transaction if such transaction is not also a “change in the ownership or effective control of” the Company or “a change in the ownership of a substantial portion of the assets of” the Company, as determined under Treasury Regulation Section 1.409A-3(i)(5) (without regard to any alternative definition thereunder).

(k) “Designated 423 Corporation” means any Related Corporation selected by the Board as eligible to participate in the 423 Component.

(l) “Designated Company” means a Designated Non-423 Corporation or Designated 423 Corporation.

(m) “Designated Non-423 Corporation” means any Related Corporation or Affiliate selected by the Board as eligible to participate in the Non-423 Component.

(n) “Director” means a member of the Board.

(o) “Eligible Employee” means an Employee who meets the requirements set forth in the applicable Offering Document for eligibility to participate in the Offering, provided that such Employee also meets the requirements for eligibility to participate set forth in the Plan.

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(p) “Employee” means any person, including an Officer or Director, who is treated as an employee in the records of the Company or a Related Corporation (including an Affiliate). However, service solely as a Director, or payment of a fee for such services, will not cause a Director to be considered an “Employee” for purposes of the Plan.

(q) “Employee Stock Purchase Plan” means a plan that grants Purchase Rights intended to be options issued under an “employee stock purchase plan,” as that term is defined in Section 423(b) of the Code.

(r) “Fair Market Value” means, as of any date, the value of a share of Common Stock determined as follows:

i. If the shares of Common Stock are listed on any established stock exchange or traded on any established market, the Fair Market Value of a share of Common Stock will be the closing sales price for such stock as quoted on such exchange or market (or the exchange or market with the greatest volume of trading in the shares of Common Stock) on the date of determination, as reported in such source as the Board deems reliable. Unless otherwise provided by the Board, if there is no closing sales price for a share of Common Stock on the date of determination, then the Fair Market Value will be the closing sales price on the last preceding date for which such quotation exists.

ii. In the absence of such markets for the shares of Common Stock, the Fair Market Value will be determined by the Board in good faith in compliance with applicable laws.

iii. Notwithstanding the foregoing, for any Offering that begins on the IPO Date, the Fair Market Value of the shares of Common Stock on the Offering Date will be the price per share at which shares are first sold to the public in the Company’s initial public offering, as specified in the final prospectus for that initial public offering.

(s) “IPO Date” means the date of the underwriting agreement between the Company and the underwriter(s) managing the initial public offering of the shares of Common Stock, pursuant to which the shares of Common Stock are priced for the initial public offering.

(t) “Non-423 Component” means the part of the Plan, which excludes the 423 Component, pursuant to which Purchase Rights that are not intended to satisfy the requirements for Employee Stock Purchase Plans may be granted to Eligible Employees.

(u) “Offering” means the grant to Eligible Employees of Purchase Rights, with the exercise of those Purchase Rights automatically occurring at the end of one or more Purchase Periods. The terms and conditions of an Offering will generally be set forth in the “Offering Document” approved by the Board for that Offering.

(v) “Offering Date” means a date selected by the Board for an Offering to begin.

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(w) “Officer” means a person who is an officer of the Company or a Related Corporation within the meaning of Section 16 of the U.S. Securities Exchange Act of 1934, as amended, and the rules and regulations promulgated thereunder.

(x) “Participant” means an Eligible Employee who holds an outstanding Purchase Right.

(y) “Plan” means this Five9, Inc. 2014 Employee Stock Purchase Plan, including both the 423 Component and Non-423 Component, as amended from time to time.

(z) “Purchase Date” means one or more dates during an Offering selected by the Board on which Purchase Rights will be exercised and on which purchases of shares of Common Stock will be carried out in accordance with such Offering.

(aa) “Purchase Period” means a period of time specified within an Offering, generally beginning on the Offering Date or on the first Trading Day following a Purchase Date and ending on a Purchase Date. An Offering may consist of one or more Purchase Periods.

(bb) “Purchase Right” means an option to purchase shares of Common Stock granted pursuant to the Plan.

(cc) “Related Corporation” means any “parent corporation” or “subsidiary corporation” of the Company, whether now or subsequently established, as those terms are defined in Sections 424(e) and (f), respectively, of the Code.

(dd) “Section 409A” means Section 409A of the Code.

(ee) “Section 423” means Section 423 of the Code.

(ff) “Trading Day” means any day on which the exchange(s) or market(s) on which shares of Common Stock are listed, including, but not limited to, the NYSE, Nasdaq Global Select Market, the Nasdaq Global Market, the Nasdaq Capital Market or any successors thereto, is open for trading.

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