EX-4.6





 Exhibit 4.6 

DESCRIPTION OF COMMON STOCK 
 The
following summary description of the common stock of Silverback Therapeutics, Inc. (we, our or us) is based on the provisions of our amended and restated certificate of incorporation, as well as our amended and restated bylaws, and the applicable
provisions of the Delaware General Corporation Law. This information is qualified entirely by reference to the applicable provisions of our amended and restated certificate of incorporation, amended and restated bylaws, and the Delaware General
Corporation Law. Our amended and restated certificate of incorporation and amended and restated bylaws have previously been filed as exhibits with the Securities and Exchange Commission. 

Common Stock 
 Voting Rights 

Each holder of common stock is entitled to one vote for each share on all matters submitted to a vote of the stockholders. The affirmative vote of holders of
at least 66 2/3% of the voting power of all of the then-outstanding shares of capital stock, voting as a single class, will be required to amend certain provisions of our amended and restated certificate of incorporation, including provisions
relating to amending our amended and restated bylaws, the classified structure of our board of directors, the size of our board of directors, removal of directors, director liability, vacancies on our board of directors, special meetings,
stockholder notices, actions by written consent and exclusive jurisdiction. 
 Dividends 

Subject to preferences that may apply to any outstanding preferred stock, holders of our common stock are entitled to receive ratably any dividends that our
board of directors may declare out of funds legally available for that purpose on a non-cumulative basis. 

Liquidation 
 In the event of our liquidation,
dissolution or winding up, holders of our common stock will be entitled to share ratably in the net assets legally available for distribution to stockholders after the payment of all of our debts and other liabilities, subject to the satisfaction of
any liquidation preference granted to the holders of any outstanding shares of preferred stock. 
 Rights and Preferences 

Holders of our common stock have no preemptive, conversion or subscription rights, and there are no redemption or sinking fund provisions applicable to our
common stock. The rights, preferences and privileges of the holders of our common stock are subject to, and may be adversely affected by, the rights of the holders of shares of any series of our preferred stock that we may designate and issue in the
future. 
 Anti-Takeover Provisions of Delaware Law and Our Amended and Restated Certificate of Incorporation and Amended and Restated Bylaws 

Section 203 of the Delaware General Corporation Law 

We are subject to Section 203 of the Delaware General Corporation Law, which prohibits a Delaware corporation from engaging in any business combination
with any interested stockholder for a period of three years after the date that such stockholder became an interested stockholder, with the following exceptions: 
  

	 	•	 	 before such date, the board of directors of the corporation approved either the business combination or the
transaction that resulted in the stockholder becoming an interested stockholder; 















	 	•	 	 upon completion of the transaction that resulted in the stockholder becoming an interested stockholder, the
interested stockholder owned at least 85% of the voting stock of the corporation outstanding at the time the transaction began, excluding for purposes of determining the voting stock outstanding (but not the outstanding voting stock owned by the
interested stockholder) those shares owned (i) by persons who are directors and also officers and (ii) employee stock plans in which employee participants do not have the right to determine confidentially whether shares held subject to the
plan will be tendered in a tender or exchange offer; or 


  

	 	•	 	 on or after such date, the business combination is approved by the board of directors and authorized at an annual
or special meeting of the stockholders, and not by written consent, by the affirmative vote of at least 66 2/3% of the outstanding voting stock that is not owned by the interested stockholder. 



Section 203 defines a “business combination” to include the following: 

 

	 	•	 	 any merger or consolidation involving the corporation and the interested stockholder; 



 

	 	•	 	 any sale, transfer, pledge or other disposition of 10% or more of the assets of the corporation involving the
interested stockholder; 


  

	 	•	 	 subject to certain exceptions, any transaction that results in the issuance or transfer by the corporation of any
stock of the corporation to the interested stockholder; 


  

	 	•	 	 any transaction involving the corporation that has the effect of increasing the proportionate share of the stock
or any class or series of the corporation beneficially owned by the interested stockholder; and 


  

	 	•	 	 the receipt by the interested stockholder of the benefit of any loans, advances, guarantees, pledges or other
financial benefits by or through the corporation. 


 In general, Section 203 defines an “interested stockholder” as an
entity or person who, together with the person’s affiliates and associates, beneficially owns, or within three years prior to the time of determination of interested stockholder status did own, 15% or more of the outstanding voting stock of the
corporation. 
 The statute could prohibit or delay mergers or other takeover or change in control attempts and, accordingly, may discourage attempts to
acquire us even though such a transaction may offer our stockholders the opportunity to sell their stock at a price above the prevailing market price. 

Amended and Restated Certificate of Incorporation and Amended and Restated Bylaws 

Among other things, our amended and restated certificate of incorporation and amended and restated bylaws: 

 

	 	•	 	 permit our board of directors to issue up to 10,000,000 shares of preferred stock, with any rights, preferences
and privileges as they may designate, including the right to approve an acquisition or other change in control; 


  

	 	•	 	 provide that the authorized number of directors may be changed only by resolution of our board of directors;



  

	 	•	 	 provide that our board of directors will be classified into three classes of directors; 



 

	 	•	 	 provide that, subject to the rights of any series of preferred stock to elect directors, directors may only be
removed for cause, which removal may be effected, subject to any limitation imposed by law, by the holders of at least 66 2/3% of the voting power of all of our then-outstanding shares of the capital stock entitled to vote generally at an election
of directors; 















	 	•	 	 provide that all vacancies, including newly created directorships, may, except as otherwise required by law, be
filled by the affirmative vote of a majority of directors then in office, even if less than a quorum; 


  

	 	•	 	 require that any action to be taken by our stockholders must be effected at a duly called annual or special
meeting of stockholders and not be taken by written consent or electronic transmission; 


  

	 	•	 	 provide that stockholders seeking to present proposals before a meeting of stockholders or to nominate candidates
for election as directors at a meeting of stockholders must provide advance notice in writing, and also specify requirements as to the form and content of a stockholder’s notice; 



 

	 	•	 	 provide that special meetings of our stockholders may be called only by the chairman of our board of directors,
our chief executive officer or president or by our board of directors pursuant to a resolution adopted by a majority of the total number of authorized directors, and not by our stockholders; and 



 

	 	•	 	 not provide for cumulative voting rights, therefore allowing the holders of a majority of the shares of common
stock entitled to vote in any election of directors to elect all of the directors standing for election, if they should so choose. 


 The
amendment of any of these provisions would require approval by the holders of at least 662/3% of the voting power of all of our then-outstanding common stock entitled to vote generally in the election of directors, voting together as a single class.

 The combination of these provisions will make it more difficult for our existing stockholders to replace our board of directors as well as for another
party to obtain control of us by replacing our board of directors. Because our board of directors has the power to retain and discharge our officers, these provisions could also make it more difficult for existing stockholders or another party to
effect a change in management. In addition, the authorization of undesignated preferred stock makes it possible for our board of directors to issue preferred stock with voting or other rights or preferences that could impede the success of any
attempt to change our control. 
 These provisions are intended to enhance the likelihood of continued stability in the composition of our board of
directors and its policies and to discourage coercive takeover practices and inadequate takeover bids. These provisions are also designed to reduce our vulnerability to hostile takeovers and to discourage certain tactics that may be used in proxy
fights. However, such provisions could have the effect of discouraging others from making tender offers for our shares and may have the effect of delaying changes in our control or management. As a consequence, these provisions may also inhibit
fluctuations in the market price of our stock that could result from actual or rumored takeover attempts. We believe that the benefits of these provisions, including increased protection of our potential ability to negotiate with the proponent of an
unfriendly or unsolicited proposal to acquire or restructure our company, outweigh the disadvantages of discouraging takeover proposals, because negotiation of takeover proposals could result in an improvement of their terms. 

Choice of Forum 
 Our amended and restated
certificate of incorporation provides that the Court of Chancery of the State of Delaware (or, if and only if the Court of Chancery of the State of Delaware lacks subject matter jurisdiction, any state court located within the State of Delaware or,
if and only if all such state courts lack subject matter jurisdiction, the federal district court for the District of Delaware) and any appellate court therefrom will be the sole and exclusive forum for the following types of actions or proceedings
under Delaware statutory or common law: (i) any derivative action or proceeding brought on our behalf; (ii) any action or proceeding asserting a claim of breach of a fiduciary duty owed by any of our current or former directors, officers
or other employees to us or our stockholders; (iii) any action or proceeding asserting a claim against us or any of our current or former directors, officers or other employees, arising out of or pursuant to any provision of the Delaware
General Corporation Law, our certificate of incorporation or our bylaws; (iv) any action or proceeding to interpret, apply, enforce or determine the validity of our certificate 












 
of incorporation or our bylaws; (v) any action or proceeding as to which the Delaware General Corporation Law confers jurisdiction to the Court of Chancery of the State of Delaware; and
(vi) any action asserting a claim against us or any of our directors, officers or other employees governed by the internal affairs doctrine. This provision will not apply to suits brought to enforce a duty or liability created by the Securities
Act of 1933, as amended, the Securities Exchange Act of 1934, as amended, or any other claim for which the U.S. federal courts have exclusive jurisdiction. 

In addition, our amended and restated certificate of incorporation provides that, unless we consent in writing to the selection of an alternative forum, to
the fullest extent permitted by law, the federal district courts of the United States of America shall be the exclusive forum for the resolution of any complaint asserting a cause of action arising under the Securities Act of 1933, as amended. 

While the Delaware courts have determined that such choice of forum provisions are facially valid, a stockholder may nevertheless seek to bring a claim in a
venue other than those designated in the exclusive forum provisions, and there can be no assurance that such provisions will be enforced by a court in those other jurisdictions. We note that investors cannot waive compliance with the federal
securities laws and the rules and regulations thereunder. Any person or entity purchasing or otherwise acquiring any interest in our securities shall be deemed to have notice of and consented to these provisions. Although we believe these provisions
benefit us by providing increased consistency in the application of law for the specified types of actions and proceedings, the provisions may have the effect of discouraging lawsuits against us or our directors and officers. 

Listing 
 Our common stock is listed on the Nasdaq Global
Market under the trading symbol “SBTX.” 
 Transfer Agent and Registrar 

The transfer agent and registrar for our common stock is American Stock Transfer & Trust Company, LLC. The transfer agent’s address is 6201 15th
Avenue, Brooklyn, New York 11219, and its telephone number is (800) 937-5449.