Description of Registrants Securities Registered Pursuant to Section 12 of the Securities Act of 1934

Our authorized capital stock consists of 400,000,000 shares of common stock, $0.01 par value per share, and 10,000,000 shares of undesignated preferred stock, $0.01 par value per share. Our board of directors is authorized, subject to limitations prescribed by Delaware law, to issue up to 10,000,000 shares of undesignated preferred stock in one or more series, to establish from time to time the number of shares to be included in each series, and to fix the designation, powers, preferences, and rights of the shares of each series and any of its qualifications, limitations or restrictions, in each case without further vote or action by our stockholders. Our board of directors or the holders of a majority in voting power of our capital stock can also increase or decrease the number of shares of any series of preferred stock, but not below the number of shares of that series then outstanding, without any further vote or action by our stockholders.

As of January 31, 2020, there were 113,351,292 shares of our common stock issued and outstanding and no shares of our preferred stock issued and outstanding. All of the outstanding shares of our common stock are fully paid and nonassessable. Our board of directors is authorized, without stockholder approval except as required by the listing standards of the New York Stock Exchange, to issue additional shares of our capital stock.

Our common stock is listed on the New York Stock Exchange under the symbol “ZEN.”

Subject to preferences that may apply to any shares of preferred stock outstanding at the time, the holders of our common stock are entitled to receive dividends out of funds legally available for the payment of dividends if our board of directors, in its discretion, determines to issue dividends and then only at the times and in the amounts that our board of directors may determine.

Holders of our common stock are entitled to one vote for each share held of record by such holder on the applicable record date on all matters submitted to a vote of stockholders. We have not provided for cumulative voting for the election of directors in our Certificate of Incorporation. Any election of directors by stockholders in which the number of persons properly nominated to serve as directors is equal to the number of directors to be elected shall be determined by the vote of the majority of the votes cast.

If we become subject to a liquidation, dissolution, or winding-up, the assets legally available for distribution to our stockholders would be distributable ratably among the holders of our common stock and any participating preferred stock outstanding at that time, subject to prior satisfaction of all outstanding debt and liabilities and the preferential rights of and the payment of liquidation preferences, if any, on any outstanding shares of preferred stock.

Our common stock is not entitled to preemptive or exchange rights, and is not subject to conversion, redemption, or sinking fund provisions.

The transfer agent and registrar for our common stock is Computershare Trust Company, N.A.

Certain provisions of Delaware law, our Certificate of Incorporation, and our Bylaws, which are summarized below, may have the effect of delaying, deferring, or discouraging another person from acquiring control of our Company. They are also designed, in part, to encourage persons seeking to acquire control of us to negotiate first with our board of directors. We believe that the benefits of increased protection of our potential ability to negotiate with an unfriendly or unsolicited acquirer outweigh the disadvantages of discouraging a proposal to acquire us because negotiation of these proposals could result in an improvement of their terms.

We are governed by the provisions of Section 203 of the Delaware General Corporation Law. In general, Section 203 prohibits a public Delaware corporation from engaging in a “business combination” with an “interested stockholder” for a period of three years after the date of the transaction in which the person became an interested stockholder, unless the business combination is approved in a prescribed manner. A “business combination” includes mergers, asset sales, or other transactions resulting in a financial benefit to the stockholder. An “interested stockholder” is a person who, together with affiliates and associates, owns, or within three years did own, 15% or more of the corporation’s outstanding voting stock. These provisions may have the effect of delaying, deferring, or preventing a change in our control.

Our Certificate of Incorporation and our Bylaws provide for the following:

•Board of Directors Vacancies. Our Certificate of Incorporation and Bylaws authorize only our board of directors to fill vacant directorships, including newly created seats, even if less than a quorum. In addition, the number of directors constituting our board of directors is permitted to be set only by a resolution adopted by a majority vote of our entire board of directors. These provisions would prevent a stockholder from increasing the size of our board of directors and then gaining control of our board of directors by filling the resulting vacancies with its own nominees. This makes it more difficult to change the composition of our board of directors and promotes continuity of management.

•Classified Board. Our Certificate of Incorporation and Bylaws provide that our board of directors is classified into three staggered classes of directors. One class is elected each year at the annual meeting of stockholders for a term of three years. A third party may be discouraged from making a tender offer or otherwise attempting to obtain control of us as it is more difficult and time consuming for stockholders to replace a majority of the directors on a classified board of directors.

•Stockholder Action; Special Meeting of Stockholders. Our Certificate of Incorporation and Bylaws require that any action to be taken by our stockholders be effected at a duly called annual or special meeting of our stockholders and not by written consent. As a result, a holder controlling a majority of our capital stock would not be able to amend our Bylaws or remove directors without holding a meeting of our stockholders called in accordance with our Bylaws. Our Certificate of Incorporation and Bylaws further provide that special meetings of our stockholders may be called only by our board of directors, the Chair of our board of directors, or our Chief Executive Officer (pursuant to a resolution approved by the affirmative vote of a majority of the directors then in office), therefore prohibiting a stockholder from calling a special meeting. These provisions might delay the ability of our stockholders to force consideration of a proposal or for stockholders controlling a majority of our capital stock to take any action, including the removal of directors.

•Advance Notice Requirements for Stockholder Proposals and Director Nominations. Our Bylaws establish advance notice procedures for stockholders seeking to bring business before our annual meeting of stockholders or to nominate candidates for election as directors at our annual meeting of stockholders. Our Bylaws also specify certain requirements regarding the form and content of a stockholder’s notice. These provisions might preclude our stockholders from bringing matters before our annual meeting of stockholders or from making nominations for directors at our annual meeting of stockholders if the proper procedures are not followed. These provisions may also discourage or deter a potential acquirer from conducting a solicitation of proxies to elect the acquirer’s own slate of directors or otherwise attempting to obtain control of our Company.

•No Cumulative Voting. The Delaware General Corporation Law provides that stockholders are not entitled to cumulate votes in the election of directors unless a corporation’s certificate of incorporation provides otherwise. Our Certificate of Incorporation does not provide for cumulative voting.

•Directors Removed Only for Cause. Our Certificate of Incorporation provides that our directors may be removed only for cause and only by the affirmative vote of the holders of 75% or more of the outstanding shares of capital stock entitled to vote at an election of directors.

•Amendment of Charter Provisions. The amendment of our Bylaws and certain provisions of our Certificate of Incorporation requires approval of our board of directors or the holders of at least 75% of our outstanding shares of capital stock then entitled to vote.

•Issuance of Undesignated Preferred Stock. Our board of directors has the authority, without further action by the stockholders, to issue up to 10,000,000 shares of undesignated preferred stock with rights and preferences, including voting rights, designated from time to time by our board of directors that may be senior to our common stock. The existence of authorized but unissued shares of preferred stock enables our board of directors to render more difficult or to discourage an attempt to obtain control of us by means of a merger, tender offer, proxy contest, or other means.

•Exclusive Jurisdiction for Certain Actions. Our Certificate of Incorporation and Bylaws provide that unless we consent in writing to the selection of an alternative forum, the Court of Chancery of the State of Delaware shall be the sole and exclusive forum for (A) any derivative action or proceeding brought on our behalf, (B) any action asserting a claim of breach of a fiduciary duty owed by any of our directors, officers, or other employees to us or our stockholders, (C) any action asserting a claim arising pursuant to any provision of the Delaware General Corporation Law, our Certificate of Incorporation or our Bylaws, or (D) any action asserting a claim against us governed by the internal affairs doctrine. Although we believe this provision benefits us by providing increased consistency in the application of Delaware law in the types of lawsuits to which it applies, the provision may have the effect of discouraging lawsuits against our directors and officers. The enforceability of similar exclusive forum provisions in other companies’ certificates of incorporation has been challenged in legal proceedings, and it is possible that a court could rule that this provision in our Certificate of Incorporation is inapplicable or unenforceable.