Description of Securities

Exhibit 4.3

DESCRIPTION OF THE REGISTRANT’S SECURITIES REGISTERED PURSUANT TO SECTION 12
OF THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED

The following summary sets forth certain material terms and provisions of our securities that are registered under Section 12 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”). This description also summarizes relevant provisions of the General Corporation Law of Delaware (the “DGCL”). The following description is a summary and does not purport to be a complete description of the rights and preferences of our securities. It is subject to, and qualified in its entirety by reference to, the applicable provisions of the DGCL and our Second Amended and Restated Certificate of Incorporation (the “Amended and Restated Charter”), and our Amended and Restated Bylaws (the “Amended and Restated Bylaws”), each of which is incorporated by reference as an exhibit to the Annual Report on Form 10-K of which this Exhibit 4.3 is a part. We encourage you to read our Amended and Restated Certificate of Incorporation, our Bylaws, and the applicable provisions of the DGCL for additional information. Capitalized terms but not defined herein shall have the meanings ascribed to such terms as set forth in the Annual Report on Form 10-K of which this Exhibit 4.3 is a part.

General

Our authorized capital stock consists of 60 million shares of common stock, par value $0.0001 per share, and 10 million shares of preferred stock, par value $0.0001 per share. As of December 31, 2023, we had 23,124,888 shares of Common Stock outstanding and no shares of preferred stock were outstanding.

Common Stock

Dividend Rights

Subject to applicable law and the rights, if any, of the holders of any outstanding series of preferred stock, the holders of outstanding shares of Common Stock will be entitled to receive dividends and other distributions out of assets legally available at the times and in the amounts as our board of directors may determine from time to time.

Voting Rights

Each outstanding share of Common Stock is entitled to one vote on all matters submitted to a vote of stockholders. Holders of shares of Common Stock shall have no cumulative voting rights.

Preemptive Rights

Our Common Stock is not entitled to preemptive or other similar subscription rights to purchase any of our securities.

Conversion or Redemption Rights

Our Common Stock is neither convertible nor redeemable.

Liquidation Rights

Subject to applicable law and the rights, if any, of the holders of any outstanding series of preferred stock, in the event of any voluntary or involuntary liquidation, dissolution or winding up of Peak Bio, the holders of our Common Stock will be entitled to receive all the remaining assets of Peak Bio available for distribution to stockholders, after payment or provision for payment of the debts and other liabilities of Peak Bio.

Preferred Stock

Our board of directors is expressly authorized to provide, out of the unissued shares of preferred stock for one or more series of preferred stock, and to establish from time to time the number of shares to be included in each such series and to fix the voting rights, if any, designations, powers, preferences and relative, participating, optional, special and other rights, if any, of each such series and any qualifications, limitations and restrictions thereof, as shall be stated in the resolution or resolutions adopted by the board of directors providing for the issuance of such series and included in a certificate of designation filed pursuant to the DGCL, and the board of directors is expressly vested with the authority to the full extent provided by law, to adopt any such resolution or resolutions.

Warrants

Each whole warrant (the “Warrant”) will automatically entitle the registered holder to purchase one whole share of our Common Stock at a price of $11.50 per share for the Public Warrants and private placement warrants initially issued to the Sponsor (the “Private Placement Warrants”) and $0.01 per share for the PIPE Warrants, subject to adjustment as discussed below, at any time commencing on the date that is 30 days after the closing of the Business Combination. Pursuant to the warrant agreement, a warrantholder may exercise its warrants only for a whole number of shares of our Common Stock. This means that only a whole Warrant may be exercised at any given time by a warrantholder. The Public Warrants and Private Placement Warrants will expire five years after the completion of the Business Combination and the PIPE Warrants will expire one year after the completion of the Business Combination, at 5:00 p.m., New York City Time, respectively, or earlier upon redemption or liquidation.

We will not be obligated to deliver any shares of our Common Stock pursuant to the exercise for cash of a Warrant and will have no obligation to settle such warrant exercise unless a registration statement under the Securities Act with respect to the shares of our Common Stock underlying the warrants is then effective and a prospectus relating thereto is current, subject to our satisfying our obligations described below with respect to registration. No Warrant will be exercisable and we will not be obligated to issue shares of our Common Stock upon exercise of a Warrant unless our Common Stock issuable upon such warrant exercise has been registered, qualified or deemed to be exempt from the registration or qualifications requirements of the securities laws of the state of residence of the registered holder of the Warrants.

Notwithstanding the foregoing, if a registration statement covering the shares of common stock issuable upon exercise of the Public Warrants is not effective within a specified period following the consummation of the Business Combination, warrant holders may, until such time as there is an effective registration statement and during any period when we shall have failed to maintain an effective registration statement, exercise warrants on a cashless basis pursuant to the exemption provided by Section 3(a)(9) of the Securities Act, provided that such exemption is available. If that exemption, or another exemption, is not available, holders will not be able to exercise their warrants on a cashless basis. In the event of such cashless exercise, each holder would pay the exercise price by surrendering the warrants for that number of shares of common stock equal to the quotient obtained by dividing (x) the product of the number of shares of common stock underlying the warrants, multiplied by the difference between the exercise price of the warrants and the “fair market value” (defined below) by (y) the fair market value. The “fair market value” for this purpose will mean the average reported last sale price of the shares of common stock for the 5 trading days ending on the trading day prior to the date of exercise.

The Private Warrants are identical to the Public Warrants except that such warrants will be exercisable for cash or on a cashless basis, at the holder’s option, and will not be redeemable by us, in each case so long as they are still held by the Sponsor or its permitted transferees.

We may call the warrants for redemption (excluding the Private Warrants), in whole and not in part, at a price of $0.01 per warrant,

The right to exercise will be forfeited unless the warrants are exercised prior to the date specified in the notice of redemption. On and after the redemption date, a record holder of a warrant will have no further rights except to receive the redemption price for such holder’s warrant upon surrender of such warrant.

The redemption criteria for our Warrants have been established at a price which is intended to provide warrant holders a reasonable premium to the initial exercise price and provide a sufficient differential between the then-prevailing share price and the warrant exercise price so that if the share price declines as a result of our redemption call, the redemption will not cause the share price to drop below the exercise price of the Warrants.

If we call the Warrants for redemption as described above, our management will have the option to require all holders that wish to exercise warrants to do so on a “cashless basis.” In such event, each holder would pay the exercise price by surrendering the Warrants for that number of shares of Common Stock equal to the quotient obtained by dividing (x) the product of the number of shares of Common Stock underlying the Warrants, multiplied by the difference between the exercise price of the Warrants and the “fair market value” (defined below) by (y) the fair market value. The “fair market value” for this purpose shall mean the average reported last sale price of the shares of common stock for the 5 trading days ending on the third trading day prior to the date on which the notice of redemption is sent to the holders of Warrants.

The Warrants have been issued in registered form under a warrant agreement between Continental Stock Transfer & Trust Company, as warrant agent, and us. The warrant agreement provides that the terms of the warrants may be amended without the consent of any holder to cure any ambiguity or correct any defective provision, but requires the approval, by written consent or vote, of the holders of at least a majority of the then outstanding public warrants in order to make any change that adversely affects the interests of the registered holders. The exercise price and number of shares of common stock issuable on exercise of the Warrants may be adjusted in certain circumstances including in the event of a stock dividend, extraordinary dividend or our recapitalization, reorganization, merger or consolidation. However, except as described below, the warrants will not be adjusted for issuances of shares of Common Stock at a price below their respective exercise prices.

In addition, if (x) we issued additional shares of Common Stock or equity-linked securities for capital raising purposes in connection with the closing of the Business Combination at an issue price or effective issue price of less than $9.20 per share of common stock (with such issue price or effective issue price to be determined in good faith by our board of directors, and in the case of any such issuance to our sponsor, initial stockholders or their affiliates, without taking into account any founders’ shares held by them prior to such issuance), (y) the aggregate gross proceeds from such issuances represent more than 60% of the total equity proceeds, and interest thereon, available for the funding of the Business Combination on the date of the consummation of the Business Combination (net of redemptions), and (z) the Market Value (as defined in the warrant agreement) is below $9.20 per share, the exercise price of the Warrants will be adjusted (to the nearest cent) to be equal to 115% of the greater of (i) the Market Value or (ii) the price at which we issue the additional shares of Common Stock or equity-linked securities.

The Warrants may be exercised upon surrender of the warrant certificate on or prior to the expiration date at the offices of the warrant agent, with the exercise form on the reverse side of the warrant certificate completed and executed as indicated, accompanied by full payment of the exercise price, by certified or official bank check payable to us, for the number of Warrants being exercised. The warrant holders do not have the rights or privileges of holders of shares of Common Stock and any voting rights until they exercise their warrants and receive shares of Common Stock. After the issuance of shares of Common Stock upon exercise of the Warrants, each holder will be entitled to one vote for each share held of record on all matters to be voted on by stockholders.

Warrant holders may elect to be subject to a restriction on the exercise of their warrants such that an electing warrant holder would not be able to exercise their warrants to the extent that, after giving effect to such exercise, such holder would beneficially own in excess of 9.8% of the shares of common stock outstanding.

No fractional shares will be issued upon exercise of the warrants. If, upon exercise of the Warrants, a holder would be entitled to receive a fractional interest in a share, we will, upon exercise, round up to the nearest whole number the number of shares of Common Stock to be issued to the warrant holder.

Anti-Takeover Effects of Our Certificate of Incorporation and Bylaws

Our Amended and Restated Charter, Amended and Restated Bylaws and the DGCL contain provisions, which are summarized in the following paragraphs, that are intended to enhance the likelihood of continuity and stability in the composition of our board of directors. These provisions are intended to avoid costly takeover battles, reduce our vulnerability to a hostile change of control and enhance the ability of our board of directors to maximize stockholder value in connection with any unsolicited offer to acquire us. However, these provisions may have an anti-takeover effect and may delay, deter or prevent a merger or acquisition of Peak Bio by means of a tender offer, a proxy contest or other takeover attempt that a stockholder might consider in its best interest, including those attempts that might result in a premium over the prevailing market price for the Common Stock held by stockholders.

Classified Board

Our Amended and Restated Charter will be divided into three classes of directors, divided further into classes of two, two and three directors, and with the directors serving three-year terms. As a result, approximately one-third of our board of directors will be elected each year. The classification of directors will have the effect of making it more difficult for stockholders to change the composition of our board of directors. Our Amended and Restated Charter also provides that, subject to any rights of holders of preferred stock to elect additional directors under specified circumstances, the number of directors will be fixed exclusively pursuant to a resolution adopted by our board of directors.

Stockholder Action by Written Consent

Our Amended and Restated Charter provide that except as otherwise expressly provided for pursuant to any Certificate of Designation permitting the holders of one or more series of preferred stock to act by written consent, any action required or permitted to be taken by our stockholders must be effected by a duly called annual or special meeting of such stockholders and may not be effected by written consent.

Special Meetings of Stockholders

Our Amended and Restated Charter provides that, subject to the rights, if any, of the holders of any outstanding series of preferred stock, and to the requirements of applicable law, special meetings of stockholders may be called only by the Chairman of the Board, the Chief Executive Officer of Peak Bio or the board of directors pursuant to a resolution adopted by a majority of the board of directors. Our Amended and Restated Bylaws prohibit the conduct of any business at a special meeting other than as specified in the notice for such meeting. These provisions may have the effect of deferring, delaying or discouraging hostile takeovers, or changes in control or management of Peak Bio.

Advance Notice Procedures

Our Amended and Restated Bylaws establish an advance notice procedure for stockholder proposals to be brought before an annual meeting of our stockholders, including proposed nominations of persons for election to our board of directors. Stockholders at an annual meeting will only be able to consider proposals or nominations specified in the notice of meeting or brought before the meeting by or at the direction of our board of directors or by a stockholder who was a stockholder of record on the record date for the meeting, who is entitled to vote at the meeting and who has given our Secretary timely written notice, in proper form, of the stockholder’s intention to bring that business before the meeting. Although our Amended and Restated Bylaws does not give our board of

directors the power to approve or disapprove stockholder nominations of candidates or proposals regarding other business to be conducted at a special or annual meeting, the bylaws may have the effect of precluding the conduct of certain business at a meeting if the proper procedures are not followed or may discourage or deter a potential

acquirer from conducting a solicitation of proxies to elect its own slate of directors or otherwise attempting to obtain control of Peak Bio.

Removal of Directors; Vacancies

Our Amended and Restated Charter provides that directors may be removed only with cause upon the affirmative vote of holders of a majority of the voting power of all then outstanding shares of stock entitled to vote generally in the election of directors, voting together as a single class. In addition, our Amended and Restated Charter provides that, subject to the rights granted to one or more series of preferred stock then outstanding, any newly created directorship on our board of directors that results from an increase in the number of directors and any vacancies on our board of directors will be filled only by the affirmative vote of a majority of the remaining directors, even if less than a quorum, or by a sole remaining director.

Amendments to Bylaws and Certificate of Incorporation

Our Amended and Restated Charter and Amended and Restated Bylaws provides that our board of directors is expressly authorized to adopt, amend, alter or repeal our Amended and Restated Bylaws without a stockholder vote. Any adoption, amendment, alteration or repeal of our Amended and Restated Bylaws by our stockholders will require the affirmative vote of holders of at least a majority of the voting power of all then outstanding shares of our capital stock entitled to vote generally in the election of directors, voting together as a single class.

The DGCL provides generally that the affirmative vote of a majority of the outstanding shares entitled to vote thereon, voting together as a single class, is required to amend a corporation’s certificate of incorporation, unless the certificate of incorporation requires a greater percentage.

The combination of the classification of our board of directors and the lack of cumulative voting 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.

Authorized but Unissued Shares

Our authorized but unissued shares of common stock and preferred stock will be available for future issuance without stockholder approval, subject to stock exchange rules. These additional shares may be utilized for a variety of corporate purposes, including future public offerings to raise additional capital, corporate acquisitions and employee benefit plans. One of the effects of the existence of authorized but unissued common stock or preferred stock may be to enable our board of directors to issue shares to persons friendly to current management, which issuance could render more difficult or discourage an attempt to obtain control of Peak Bio by means of a merger, tender offer, proxy contest or otherwise, and thereby protect the continuity of our management and possibly deprive our stockholders of opportunities to sell their shares of common stock at prices higher than prevailing market prices.

Business Combinations

Upon completion of the Business Combination, we are now subject to the provisions of Section 203 of the DGCL. In general, Section 203 prohibits a publicly held Delaware corporation from engaging in a “business combination” with an “interested stockholder” for a three-year period following the time that the person 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 unless it satisfies one of the following conditions: (1) 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; (2) 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 (3) at or after the time the stockholder became an interested stockholder, the business combination was approved by the board of directors and authorized at an annual or special meeting of the stockholders by the affirmative vote of at least two-thirds (2/3) of the outstanding voting stock which is not owned by the interested stockholder.

A Delaware corporation may “opt out” of these provisions with an express provision in its original certificate of incorporation or an express provision in its certificate of incorporation or bylaws resulting from a stockholders’ amendment approved by at least a majority of the outstanding voting shares.

We have not opted out of Section 203.

Under certain circumstances, this provision will make it more difficult for a person who would be an “interested stockholder” to effect various business combinations with us for a three-year period. This provision may encourage companies interested in acquiring us to negotiate in advance with our board of directors because the stockholder approval requirement would be avoided if our board of directors approves either the business combination or the transaction which results in the stockholder becoming an interested stockholder. These provisions also may have the effect of preventing changes in our board of directors and may make it more difficult to accomplish transactions which stockholders may otherwise deem to be in their best interests.

Dissenters’ Rights of Appraisal and Payment

Under the DGCL, with certain exceptions, our stockholders will have appraisal rights in connection with a merger or consolidation of us. Pursuant to the DGCL, stockholders who properly request and perfect appraisal rights in connection with such merger or consolidation will have the right to receive payment of the fair value of their shares as determined by the Delaware Court of Chancery.

Stockholders’ Derivative Actions

Under the DGCL, any of our stockholders may bring an action in our name to procure a judgment in our favor, also known as a derivative action, provided that the stockholder bringing the action is a holder of our shares at the time of the transaction to which the action relates or such stockholder’s stock thereafter devolved by operation of law.

Exclusive Forum

Our Amended and Restated Charter provides that, unless we consent in writing to the selection of an alternative forum, the Court of Chancery of the State of Delaware (or, if the Court of Chancery does not have subject matter jurisdiction, any state court located in Delaware, or if all such state courts lack subject matter jurisdiction, the United States District Court for the District of Delaware) will be the sole and exclusive forum for (1) any derivative action or proceeding brought on our behalf, (2) 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, (3) any action

asserting a claim against us or any director, officer or other employee arising pursuant to any provision of the DGCL, our Amended and Restated Charter or our Amended and Restated Bylaws, (4) any action asserting a claim against us or any director, officer or employee that is governed by the internal affairs doctrine or (5) any action asserting an “internal corporate claim” as such term is defined in Section 115 of the DGCL; provided that for the avoidance of doubt, the forum selection provision that identifies the Court of Chancery of the State of Delaware as the exclusive forum for certain litigation, including any “derivative action”, will not apply to suits to enforce a duty or liability created by the Securities Act, the Exchange Act or any other claim for which the federal courts have exclusive jurisdiction. Section 22 of the Securities Act creates concurrent jurisdiction for state and federal courts over all suits brought to enforce any duty or liability created by the Securities Act or the rules and regulations

thereunder. Section 27 of the Exchange Act creates exclusive federal jurisdiction over all suits brought to enforce any duty or liability created by the Exchange Act or the rules and regulations thereunder. Any person or entity purchasing or otherwise acquiring any interest in shares of our capital stock will be deemed to have notice of and to have consented to the provisions of our Amended and Restated Charter described above. Although we believe these provisions benefit us by providing increased consistency in the application of Delaware 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.

Conflicts of Interest

Delaware law permits corporations to adopt provisions renouncing any interest or expectancy in certain opportunities that are presented to the corporation or its officers, directors or stockholders. Our Amended and Restated Charter, to the extent permitted by Delaware law, renounces any interest or expectancy that we have in, or right to be offered an opportunity to participate in, specified business opportunities that are from time to time presented to certain of our officers, directors or stockholders. Our Amended and Restated Charter does not renounce our interest in any business opportunity that is expressly offered to a director or officer solely in his or her capacity as a director or officer of Peak Bio. To the fullest extent permitted by law, no business opportunity will be deemed to be a potential corporate opportunity for us unless we would be permitted to undertake the opportunity under our Amended and Restated Charter, and the opportunity would be in line with our business.

Limitations on Liability and Indemnification of Officers and Directors

The DGCL authorizes corporations to limit or eliminate the personal liability of directors to corporations and their stockholders for monetary damages for breaches of directors’ fiduciary duties, subject to certain exceptions. Our Amended and Restated Charter includes a provision that eliminates the personal liability of directors for monetary damages for any breach of fiduciary duty as a director, except to the extent such exemption from liability or limitation thereof is not permitted under the DGCL. The effect of these provisions will be to eliminate the rights of us and our stockholders, through stockholders’ derivative suits on our behalf, to recover monetary damages from a director for breach of fiduciary duty as a director. However, exculpation will not apply to any director if the director has acted in bad faith, knowingly or intentionally violated the law, authorized unlawful payments of dividends, stock purchases or redemptions, or derived an improper personal benefit from his or her actions as a director.

Our Amended and Restated Bylaws provide that we must indemnify and advance expenses to our directors and officers to the fullest extent authorized by the DGCL. We are also expressly authorized to carry directors’ and officers’ liability insurance providing indemnification for our directors, officers and certain employees for some liabilities. We believe that these indemnification and advancement provisions and insurance will be useful to attract and retain qualified directors and officers.

The limitation of liability, indemnification and advancement provisions that are included in Our Amended and Restated Charter and Amended and Restated Bylaws may discourage stockholders from bringing a lawsuit against directors for breaches of their fiduciary duty. These provisions also may have the effect of reducing the likelihood of derivative litigation against directors and officers, even though such an action, if successful, might otherwise benefit us and our stockholders. In addition, your investment may be adversely affected to the extent we pay the costs of settlement and damage awards against directors and officers pursuant to these indemnification provisions.

Transfer Agent and Registrar

The transfer agent and registrar for our shares of Common Stock and Warrants is Continental Stock Transfer & Trust Company. The transfer agent’s address is 1 State Street, 30th Floor, New York, NY 10004.