Exhibit 4.05

    

    

    

    
      Description of ACM Research, Inc. Securities

       

      
        The following information constitutes the “Description of Securities” required by Item 202(a) of Regulation S-K. As of March 1, 2021, ACM Research, Inc.
          has one class of securities registered under Section 12 of the Securities Exchange Act of 1934, as amended, which is its Class A common stock, $0.0001 par value per share.

      

       

      References herein to “we,” “our,” “us,” or “our company” refer to ACM Research, Inc., a Delaware corporation. The following information summarizes the
        material terms of our common and preferred stock and warrants, as well as relevant provisions of our charter, which includes certificates of designations relating to each series of our preferred stock, and bylaws, the Delaware General Corporation
        Law and the Warrant (as defined below). For a complete description of the terms of our common stock and other securities, please refer to our charter and bylaws and the Warrant.

       

      Authorized Capital Stock

       

      Our authorized capital stock consists of 50,000,000 shares of Class A common stock, $0.0001 par value per share, 2,409,738 shares of Class B common
        stock, $0.0001 par value per share, and 10,000,000 shares of preferred stock, $0.0001 par value per share. Class A common stock and Class B common stock are referred to collectively as common stock. Authorized but unissued shares of Class B Common
        Stock are not available for reissuance.

       

      Common Stock

       

      Voting Rights

       

      Except as otherwise required by Delaware law, at every annual or special meeting of stockholders, holders of Class B common stock are entitled to
        twenty votes per share and holders of Class A common stock are entitled to one vote per share. The holders of Class A common stock and Class B common stock vote together as a single class, unless otherwise required by law.

       

      Dividends

       

      Subject to preferences that may be applicable to any then outstanding preferred stock, the holders of our outstanding shares of common stock are
        entitled to receive dividends, if any, as may be declared from time to time by the board of directors out of legally available funds. The holders of Class A common stock and Class B common stock are entitled to share equally, identically and
        ratably, on a per share basis, with respect to any dividend or distribution unless different treatment of the shares of each such class is approved by the affirmative vote of the holders of a majority of the outstanding shares of Class A common
        stock and Class B common stock, each voting separately as a class. At present, we have no plans to issue dividends.

       

      Liquidation

       

      In the event of our liquidation, dissolution or winding up, holders of 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.

       

      Conversion

       

      Each outstanding share of Class B common stock is convertible into one share of Class A common stock (a) at any time, at the option of the holder, or
        (b) upon any transfer of such share of Class B common stock, whether or not for value, except for certain transfers described in our charter, including transfers to family members, trusts solely for the benefit of the stockholder or their family
        members, and partnerships, corporations, and other entities exclusively owned by the stockholder or their family members. Once converted or transferred and converted into Class A common stock, shares of Class B common stock will not be reissued.

       

      
        
          


      

      Other Rights and Preferences

       

      Other than as described above, holders of common stock have no preemptive, conversion or subscription rights, and there are no redemption or sinking
        fund provisions applicable to common stock. The rights, preferences and privileges of the holders of common stock are subject to, and may be adversely affected by, the rights of the holders of shares of any series of preferred stock that we may
        designate and issue in the future.

       

      Preferred Stock

       

      Under the terms of our charter, the board of directors is authorized to issue up to 10,000,000 shares of preferred stock in one or more series, to
        establish the number of shares to be included in each such series, and to fix the designation, powers, preferences and rights of such shares and any qualifications, limitations or restrictions thereof. These rights, preferences and privileges could
        include dividend rights, conversion rights, voting rights, terms of redemption, liquidation preferences, sinking fund terms and other provisions, any or all of which may be greater than the rights of common stock. The issuance of preferred stock
        with voting and conversion rights may adversely affect the voting power of the holders of common stock, including the loss of voting control to others, and the likelihood that such holders will receive dividend payments and payments upon our
        liquidation. In addition, the issuance of preferred stock could have the effect of delaying, deferring or preventing a change in control of our company or other corporate action.

       

      Anti-Takeover Provisions

       

      So long as the outstanding shares of Class B common stock represent a majority of the combined voting power of common stock, the holders of Class B
        common stock will effectively control all matters submitted to our stockholders for a vote, as well as the overall management and direction of our company, which will have the effect of delaying, deferring or discouraging another person from
        acquiring control of our company.

       

      After such time as the shares of Class B common stock no longer represent a majority of the combined voting power of common stock, the provisions of
        Delaware law, and our charter and our bylaws may have the effect of delaying, deferring or discouraging another person from acquiring control of our company.

       

      Delaware Law

       

      Section 203 of the Delaware General Corporation Law prevents some Delaware corporations from engaging, under some circumstances, in a business
        combination, which includes a merger or sale of at least 10% of the corporation’s assets with any interested stockholder, meaning a stockholder who, together with affiliates and associates, owns or, within three years prior to the determination of
        interested stockholder status, did own 15% or more of the corporation’s outstanding voting stock, unless:

       

      	

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              the transaction is approved by the board of directors prior to the time that the interested stockholder became an interested stockholder;

            


       

      	

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              upon consummation of the transaction, which resulted in the stockholder’s becoming an interested stockholder, the interested stockholder owned at least 85% of the voting stock
                of the corporation outstanding at the time the transaction commenced, excluding stock owned by directors who are also officers of the corporation; or

            


       

      	

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              subsequent to such time that the stockholder became an interested stockholder the business combination is approved by the board and authorized at an annual or special meeting
                of stockholders by at least two-thirds of the outstanding voting stock that is not owned by the interested stockholder.

            


       

      A Delaware corporation may “opt out” of these provisions with an express provision in its original charter or an express provision in its charter or
        bylaws resulting from a stockholders’ amendment approved by at least a majority of the outstanding voting shares. We have not opted out of these provisions. As a result, mergers or other takeover or
        change in control attempts of us may be discouraged or prevented.

       

      
        
          


      

      Warrants

       

      On July 29, 2020 we issued a warrant to purchase 242,681 shares of our Class A common stock at a purchase price of $7.50 per share for an aggregate
        exercise price of $1,820,107.50, which we refer to as the Warrant.  The Warrant may be exercised during the period beginning immediately after the receipt by the warrant holder, as confirmed by us, of
          all approvals required of the governmental department and other regulatory bodies of the People’s Republic of China and ending at 5 p.m., Eastern standard time, on December 31, 2023.

       

      The exercise price and the number of warrant shares are subject to appropriate adjustment from time to time in order to prevent dilution of the
        purchase rights granted under the Warrant. Such adjustment will occur in the event that we:

       

      	

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              pay a dividend or makes any other distribution upon any capital stock payable either in Class A common stock or in securities that are convertible into Class A common stock
                without payment of any consideration; or

            


      	

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              subdivide (by any stock split, recapitalization or otherwise) outstanding Class A common stock into a greater number of shares.

            


       

      Such adjustment will also occur in the event of any of any of the following actions, in each case that entitles the holders of Class A common stock to
        receive (either directly or upon subsequent liquidation) stock, securities or assets with respect to or in exchange for Class A common stock:

       

      	

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              a reorganization of our company;

            


      	

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              reclassification of our stock (other than a change in par value or from par value to no par value or from no par value to par value or as a result of a stock dividend or
                subdivision, split-up or combination of shares);

            


      	

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              our consolidation or merger;

            


      	

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              a sale of all or substantially all of our assets; or

            


      	

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              other similar transaction.

            


       

      Charter and Bylaw Provisions

       

      Our charter and bylaws include a number of provisions that may have the effect of deterring hostile takeovers or delaying or preventing changes in
        control of our company, even after such time as the shares of Class B common stock no longer represent a majority of the combined voting power of common stock, including the following:

       

      •          Separate Class B Vote for Certain Transactions. Until the first date on which the outstanding shares of Class B common stock represent less than 35% of the combined voting
            power of common stock, any transaction that would result in a change in control of our company will require the approval of a majority of our outstanding Class B common stock voting as a separate class. This provision could delay or prevent the
            approval of a change in control that might otherwise be approved by a majority of outstanding shares of Class A and Class B common stock, voting together on a combined basis.

       

      •           Dual Class Stock. As described above in “—Common Stock—Voting Rights” above, our charter provides for a dual class common stock structure, which provides certain members of
            our senior management with the ability to control the outcome of matters requiring stockholder approval, even if they collectively own significantly less than a majority of the shares of our outstanding Class A and Class B common stock,
            including the election of directors and significant corporate transactions, such as a merger or other sale of our company or its assets.

       

      •           Supermajority Approvals. Our charter and bylaws provide that when the outstanding shares of Class B common stock represent less than a majority of the combined voting power of
            common stock, certain amendments to our charter or bylaws will require the approval of two-thirds of the combined vote of our then-outstanding shares of Class A and Class B common stock. This will have the effect of making it more difficult to
            amend our charter or bylaws to remove or modify certain provisions.

       

      •         Board of Directors Vacancies. Our charter and bylaws provide that stockholders may fill vacant directorships. When the outstanding shares of Class B common stock represent
            less than a majority of the combined voting power of common stock, our charter and bylaws authorize only the board of directors to fill vacant directorships. In addition, the number of directors constituting the board is set only by resolution
            adopted by a majority vote of our entire board. These provisions restricting the filling of vacancies will prevent a stockholder from increasing the size of the board and gaining control of the board by filling the resulting vacancies with its
            own nominees. Our charter provides that directors may be removed with or without cause only by the affirmative vote of the holders of at least two-thirds of the votes that all of the stockholders would be entitled to cast in any annual election
            of directors.

       

      
        
          


      

      •          Classified Board. The board of directors is not currently classified. Our charter and bylaws provide that when outstanding shares of Class B common stock represent less than a
            majority of the combined voting power of common stock, the board will be classified into three classes of directors, each of which will hold office for a three-year term. In addition, thereafter, directors may be removed from the board with or
            without cause only by the affirmative vote of the holders of at least two-thirds of the voting power of the then-outstanding shares of Class A and Class B common stock. The existence of a classified board could delay a successful tender offeror
            from obtaining majority control of the board, and the prospect of that delay might deter a potential offeror.

       

      •           Stockholder Action; Special Meeting of Stockholders. Our charter provides that stockholders will be able to take action by written consent. When the outstanding shares of
            Class B common stock represent less than a majority of the combined voting power of common stock, our stockholders will no longer be able to take action by written consent, and will only be able to take action at annual or special meetings of
            our stockholders. Stockholders will not be permitted to cumulate their votes for the election of directors. The absence of cumulative voting may make it more difficult for stockholders who own less than a majority in voting power to elect any
            directors to the board of directors. Our bylaws further provide that special meetings of our stockholders may be called only by the board, the chair of the board or our chief executive officer. A stockholder may not call a special meeting,
            which may delay the ability of our stockholders to force consideration of a proposal or for holders controlling a majority in voting power of our capital stock to take any action, including the removal of director.

       

      •         Advance Notice Requirements for Stockholder Proposals and Director Nominations. Our bylaws provide advance notice procedures for stockholders seeking to bring business before
            our annual meeting of stockholders, or to nominate candidates for election as directors at any meeting of stockholders. Our bylaws also specify certain requirements regarding the form and content of a stockholder’s notice. These provisions may
            preclude our stockholders from bringing matters before our annual meeting of stockholders or from making nominations for directors at our meetings of stockholders.

       

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

       

      Choice of Forum

       

      Our charter provides that the Court of Chancery of the State of Delaware will be the
          exclusive forum for: any derivative action or proceeding brought on our behalf; any action asserting a breach of fiduciary duty; any action asserting a claim against us arising pursuant to the Delaware General Corporation Law, or our charter or
          bylaws; any action to interpret, apply, enforce, or determine the validity of our charter or bylaws; or any action asserting a claim against us that is governed by the internal affairs doctrine. The enforceability of similar choice of forum
          provisions in other companies’ certificates of incorporation has been challenged in legal proceedings, and it is possible that a court could find these types of provisions to be inapplicable or unenforceable.
          The choice of forum provision summarized above is not intended to, and would not, apply to suits brought to enforce any liability or duty created by (i) the Securities Act of
            1933 or the rules and regulations thereunder, jurisdiction over which is vested in concurrently vested in federal and state courts, or (ii) the Securities Exchange Act of 1934 or the rules and regulations thereunder, jurisdiction over which is
            exclusively vested by statute in the U.S. federal courts.

       

      Transfer Agent and Registrar

       

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

       

      Nasdaq Global Market

       

      The Class A common stock is listed on the Nasdaq Global Market under the symbol “ACMR.”