Exhibit 4.1

DESCRIPTION OF SECURITIES REGISTERED
PURSUANT TO SECTION 12 OF THE SECURITIES EXCHANGE ACT OF 1934

The summary of the general terms and provisions of the common stock, par value $0.001 per share (“Common Stock”), of Sun BioPharma, Inc., a Delaware corporation (the “Corporation”), set forth below does not purport to be complete and is subject to and qualified by reference to the Corporation’s Certificate of Incorporation, as amended (the “Certificate”), and Bylaws of the Corporation, as amended (the “Bylaws”). For additional information, please read the Certificate, Bylaws and the applicable provisions of the General Corporation Law of Delaware (the “DGCL”).

Authorized Shares

The Corporation is authorized to issue up to 110,000,000 shares of capital stock, of which 100,000,000 constitute shares of Common Stock and 10,000,000 constitute shares of preferred stock, par value $0.001 per share (“Preferred Stock”).

Common Stock

No outstanding shares of common stock is entitled to preference over any other share, and each share is equal to any other share in all respects. Holders of shares of common stock are entitled to one vote for each share held of record at each meeting of shareholders. Holders of shares of common stock are not entitled to any preemptive, subscription, conversion, redemption or sinking fund rights. The absence of preemptive rights could result in a dilution of the interest of shareholders should additional common shares be issued.

Subject to any prior rights of any Preferred Stock then outstanding, holders of common stock are entitled to receive dividends in the form of cash, property or shares of capital stock of the Corporation, when and as declared by the board of directors, provided there are sufficient net profits or surplus legally available for that purpose. In any distribution of capital assets, such as liquidation, whether voluntary or involuntary, holders of shares of common stock are entitled to receive pro rata the assets remaining after creditors have been paid in full. All of the issued and outstanding shares of common stock are non-assessable.

Anti-Takeover Provisions

The Charter Documents and the DGCL contain certain provisions that may discourage an unsolicited takeover of the Company or make an unsolicited takeover of the Company more difficult. The following are some of the more significant anti-takeover provisions that are applicable to the Company:

Delaware Anti-Takeover Law

In general, Section 203 of the DGCL prohibits a Delaware corporation with a class of voting stock listed on a national securities exchange or held of record by 2,000 or more stockholders from engaging in a Business Combination (as defined below) with an Interested Stockholder (as defined below) for a three-year period following the time that this stockholder becomes an interested stockholder, unless the Business Combination is approved in a prescribed manner. A “Business Combination” includes, among other things, a merger, asset or stock sale or other transaction resulting in a financial benefit to the Interested Stockholder. An “Interested Stockholder” is a person who, together with affiliates and associates, owns, or did own within three years prior to the determination of Interested Stockholder status, 15% or more of the corporation’s voting stock. Under Section 203, a Business Combination between a corporation and an Interested Stockholder is prohibited for three years unless it satisfies one of the following conditions:

• Before the stockholder became an Interested Stockholder, the board of directors approved either the Business Combination or the transaction which resulted in the stockholder becoming an Interested Stockholder;

• Upon consummation of the transaction which 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 commenced, excluding for purposes of determining the voting stock outstanding, shares owned by persons who are directors and also officers, and employee stock plans, in some instances; or

• At or after the time the stockholder became an Interested Stockholder, the Business Combination was approved by the board of directors of the corporation and authorized at an annual or special meeting of the stockholders by the affirmative vote of at least two-thirds of the outstanding voting stock which is not owned by the Interested Stockholder.

The DGCL permits a corporation to opt out of, or choose not to be governed by, its anti-takeover statute by expressly stating so in its original certificate of incorporation (or subsequent amendment to its certificate of incorporation or bylaws approved by its stockholders). The Certificate does not contain a provision expressly opting out of the application of Section 203 of the DGCL; therefore, the Company is subject to the anti-takeover statute.

Requirements for Advance Notification of Stockholder Nominations and Proposals

The Bylaws establish advance-notice procedures with respect to stockholder proposals to be brought before a stockholder meeting and the nomination of candidates for election as directors, other than nominations made by or at the direction of the board of directors.

Special Meetings of Stockholders

The Certificate and Bylaws provide that a special meeting of stockholders may be called only by the board of directors, the Chairman of the Board or the Chief Executive Officer of the Corporation.

Classified Board of Directors

The Certificate provides that directors are divided into three classes and elected for staggered terms. At each annual meeting, approximately one third of the directors will be elected to serve a three-year term. Directors serving staggered terms can be removed from office only for cause and only by the affirmative vote of the holders of 75% or more of the outstanding shares of stock then entitled to vote at an election of directors.

Authority of the Board of Directors 

The board of directors has the power to issue any or all of the shares of the Corporation’s capital stock, including the authority to establish one or more series of Preferred Stock and to fix the powers, preferences, rights and limitations of such class or series, without seeking stockholder approval. The board of directors has the authority to adopt and change Bylaws, subject to the right of holders of at least 66.67% of the voting power of all then-outstanding shares entitled to vote generally in the election of directors to adopt, amend or repeal Bylaws.

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