Exhibit 4.3

DESCRIPTION OF SECURITIES

The following summary of the material terms of our registered securities is not intended to be a complete summary of the rights and preferences of such securities, and is qualified by reference to our Second Amended and Restated Certificate of Incorporation (the Certificate of Incorporation), the Amended and Restated Bylaws (the Bylaws) and the warrant-related documents described herein, which are incorporated by reference as exhibits to the Annual Report on Form 10-K to which this Exhibit 4.3 is filed as an exhibit, and by applicable law. We urge you to read each of the Certificate of Incorporation, the Bylaws and the warrant-related documents described herein and the applicable provisions of the Delaware General Corporation Law (the DGCL) in their entirety for a complete description of the rights and preferences of our securities.

Certificate of Incorporation

Authorized Stock

The Certificate of Incorporation authorizes two classes of stock to be designated, respectively, “Common Stock” and “Preferred Stock.” The total number of shares of capital stock that we have authority to issue is 1,252,000,000. The total number of shares of Common Stock that we are authorized to issue is 1,250,000,000, having a par value of $0.0001 per share, and the total number of shares of Preferred Stock that we are authorized to issue is 2,000,000, having a par value of $0.0001 per share.

Common Stock

The Certificate of Incorporation provides that the Common Stock has the following rights, powers, preferences and privileges.

General

The voting, dividend, liquidation and other rights and powers of the Common Stock are subject to and qualified by the rights, powers and preferences of any series of Preferred Stock as may be designated by our Board of Directors (the Board) and outstanding from time to time.

Voting Power

Except as otherwise provided herein or expressly required by law, each holder of Common Stock, as such, is entitled to vote on each matter submitted to a vote of stockholders and is entitled to one vote for each share of Common Stock held of record by such holder as of the record date for determining stockholders entitled to vote on such matter. Except as otherwise required by law, holders of Common Stock, as such, are not entitled to vote on any amendment to Certificate of Incorporation (including any Certificate of Designation (as defined below)) that relates solely to the rights, powers, preferences (or the qualifications, limitations or restrictions thereof) or other terms of one or more outstanding series of Preferred Stock if the holders of such affected series are entitled, either separately or together with the holders of one or more other such series, to vote thereon pursuant to the Certificate of Incorporation (including any Certificate of Designation) or pursuant to the DGCL.

Subject to the rights of any holders of any outstanding series of Preferred Stock, the number of authorized shares of Common Stock may be increased or decreased (but not below the number of shares thereof then outstanding) by the affirmative vote of the holders of a majority of our stock entitled to vote, irrespective of the provisions of Section 242(b)(2) of the DGCL.

Dividends

Subject to applicable law and the rights and preferences of any holders of any outstanding series of Preferred Stock, the holders of Common Stock, as such, are entitled to the payment of dividends on the Common Stock when, as and if declared by the Board in accordance with applicable law.

Liquidation

Subject to the rights and preferences of any holders of any shares of any outstanding series of Preferred Stock, in the event of any liquidation, dissolution or winding up of our company, whether voluntary or involuntary, our funds and assets that may be legally distributed to our stockholders will be distributed among the holders of the then outstanding Common Stock pro rata in accordance with the number of shares of Common Stock held by each such holder.

Transfer Rights

Subject to applicable law and the transfer restrictions set forth in Article VII of the Bylaws, shares of Common Stock and the rights and obligations associated therewith are fully transferable to any transferee.

Preferred Stock

Shares of Preferred Stock may be issued from time to time in one or more series, each of such series to have such terms as stated or expressed herein and in the resolution or resolutions providing for the creation and issuance of such series adopted by the Board as hereinafter provided.

Authority is expressly granted to the Board from time to time to issue the Preferred Stock in one or more series, and in connection with the creation of any such series, by adopting a resolution or resolutions providing for the issuance of the shares thereof and by filing a certificate of designation relating thereto in accordance with the DGCL (a Certificate of Designation), to determine and fix the number of shares of such series and such voting powers, full or limited, or no voting powers, and such designations, preferences and relative participating, optional or other special rights, and qualifications, limitations or restrictions thereof, including without limitation thereof, dividend rights, conversion rights, redemption privileges and liquidation preferences, and to increase or decrease (but not below the number of shares of such series then outstanding) the number of shares of any series as stated and expressed in such resolutions, all to the fullest extent now or hereafter permitted by the DGCL. Without limiting the generality of the foregoing, the resolution or resolutions providing for the creation and issuance of any series of Preferred Stock may provide that such series is superior or rank equally or be junior to any other series of Preferred Stock to the extent permitted by law and the Certificate of Incorporation (including any Certificate of Designation). Except as otherwise required by law, holders of any series of Preferred Stock will be entitled only to such voting rights, if any, as shall expressly be granted thereto by the Certificate of Incorporation (including any Certificate of Designation).

The number of authorized shares of Preferred Stock may be increased or decreased (but not below the number of shares thereof then outstanding) by the affirmative vote of the holders of a majority of our stock entitled to vote, irrespective of the provisions of Section 242(b)(2) of the DGCL.

No shares of Preferred Stock are outstanding as of the date of our Annual Report on Form 10-K to which this Exhibit 4.3 is filed as an exhibit.

Public Warrants

Our public warrants (the Public Warrants) are the warrants underlying the units we issued in our initial public offering.  Each whole Public Warrant now entitles the registered holder to purchase one share of our Common Stock at a price of $11.50 per whole share, subject to adjustment as discussed below, at any time. Pursuant to that certain Warrant Agreement, dated April 6, 2021, between our company and Continental Stock Transfer & Trust Company, as the warrant agent (the Warrant Agreement), a warrant holder may exercise its Public Warrants only for a whole number of shares of Common Stock. This means that only a whole Public Warrant may be exercised at any given time by a warrant holder. If, upon exercise of the Public Warrants, a holder would be entitled to receive a fractional interest in a share, we will, upon exercise, round down to the nearest whole number the number of shares of Common Stock to be issued to the warrant holder. As a result, warrant holders not purchasing Public Warrants in multiples of three will not obtain value from the fractional interest that will not be issued. Only whole Public Warrants will trade. The Public Warrants will expire December 17, 2026 (i.e., five years after the completion of the business combination), at 5:00 p.m., New York City time, or earlier upon redemption or liquidation.

We are not obligated to deliver any shares of Common Stock pursuant to the exercise of a Public Warrant and will have no obligation to settle such exercise unless a registration statement under the Securities Act

of 1933, as amended (the Securities Act) with respect to the shares of Common Stock underlying the Public Warrants is then effective and a prospectus relating thereto is current, subject to our satisfying our obligations described below with respect to registration. No Public Warrant will be exercisable for cash or on a cashless basis, and we will not be obligated to issue any shares to holders seeking to exercise their Public Warrants, unless the issuance of the shares upon such exercise is registered or qualified under the securities laws of the state of the exercising holder, or an exemption is available. In the event that the conditions in the two immediately preceding sentences are not satisfied with respect to a Public Warrant, the holder of such Public Warrant will not be entitled to exercise such Public Warrant and such Public Warrant may have no value and expire worthless.

We have registered under the Securities Act the issuance of shares of Common Stock upon exercise of the Public Warrants. We will use our best efforts to maintain the effectiveness of such registration statement, and a current prospectus relating thereto, until the expiration of the Public Warrants in accordance with the provisions of the Warrant Agreement. Notwithstanding the above, if our Common Stock is at the time of any exercise of a Public Warrant not listed on a national securities exchange such that it satisfies the definition of a “covered security” under Section 18(b)(1) of the Securities Act, we may, at our option, require holders of Public Warrants who exercise their Public Warrants to do so a “cashless basis” in accordance with Section 3(a)(9) of the Securities Act (or any successor rule) and, in the event we so elect, we will not be required to file or maintain in effect a registration statement, but will use our best efforts to register the shares under applicable blue sky laws to the extent an exemption is not available.

Redemption of Warrants When the Price per Share of Common Stock Equals or Exceeds $18.00 — We may redeem the outstanding Public Warrants:

• in whole and not in part;

• at a price of $0.01 per Public Warrant;

• upon not less than 30 days’ prior written notice of redemption to each warrant holder; and

• if, and only if, the closing price of the Common Stock equals or exceeds $18.00 per share (as adjusted) for any 20 trading days within a 30-trading day period ending three trading days before sending the notice of redemption to warrant holders.

If and when the Warrants become redeemable, we may exercise our redemption right even if we are unable to register or qualify the underlying securities for sale under all applicable state securities laws.

Redemption of Warrants When the Price per Share of Common Stock Equals or Exceeds $10.00 — Once the Warrants become exercisable, we may redeem the outstanding Warrants:

• in whole and not in part;

• at $0.10 per Warrant upon a minimum of 30 days’ prior written notice of redemption provided that holders will be able to exercise their Warrants on a cashless basis prior to redemption and receive that number of shares based on the redemption date and the fair market value of the Common Stock;

• if, and only if, the closing price of the Common Stock equals or exceeds $10.00 per share (as adjusted) for any 20 trading days within the 30-trading day period ending three trading days before we send the notice of redemption to the warrant holders; and

• if the closing price of the Common Stock for any 20 trading days within a 30-trading day period ending three trading days before we send notice of redemption to the warrant holders is less than $18.00 per share (as adjusted).

We have established the last of the redemption criterion discussed above to prevent a redemption call unless there is at the time of the call a significant premium to the warrant exercise price. If the foregoing conditions are satisfied and we issue a notice of redemption of the Public Warrants, each warrant holder will be entitled to exercise his, her or its Public Warrant prior to the scheduled redemption date. However, the price of the Common Stock may fall below the $18.00 redemption trigger price as well as the $11.50 warrant exercise price after the redemption notice is issued.

Redemption procedures and cashless exercise. If we call the Public Warrants for redemption as described above, our management will have the option to require any holder that wishes to exercise his, her or its Public Warrant to do so on a “cashless basis.” In determining whether to require all holders to exercise their

Public Warrants on a “cashless basis,” our management will consider, among other factors, our cash position, the number of Public Warrants that are outstanding and the dilutive effect on our stockholders of issuing the maximum number of shares of Common Stock issuable upon the exercise of our Public Warrants. If our management takes advantage of this option, all holders of Public Warrants would pay the exercise price by surrendering their Public Warrants for that number of shares of Common Stock equal to the quotient obtained by dividing (i) the product of the number of shares of Common Stock underlying the Public Warrants, multiplied by the difference between the exercise price of the Public Warrants and the “fair market value” (defined below) by (ii) the fair market value. The “fair market value” means the average reported last sale price of the Common Stock for the 10 trading days ending on the third trading day prior to the date on which the notice of redemption is sent to the holders of Public Warrants. If our management takes advantage of this option, the notice of redemption will contain the information necessary to calculate the number of shares of Common Stock to be received upon exercise of the Public Warrants, including the “fair market value” in such case. Requiring a cashless exercise in this manner will reduce the number of shares to be issued and thereby lessen the dilutive effect of a warrant redemption. We believe this feature is an attractive option to us if we do not need the cash from the exercise of the Public Warrants. If we call our Public Warrants for redemption and our management does not take advantage of this option, the Sponsor and its permitted transferees would still be entitled to exercise their private placement warrants for cash or on a cashless basis using the same formula described above that other warrant holders would have been required to use had all warrant holders been required to exercise their Public Warrants on a cashless basis, as described in more detail below.

A holder of a Public Warrant may notify us in writing in the event it elects to be subject to a requirement that such holder will not have the right to exercise such Public Warrant, to the extent that after giving effect to such exercise, such person (together with such person’s affiliates), to the warrant agent’s actual knowledge, would beneficially own in excess of 9.8% (or such other amount as a holder may specify) of the shares of Common Stock outstanding immediately after giving effect to such exercise.

Anti-dilution Adjustments. If the number of outstanding shares of Common Stock is increased by a stock dividend payable in shares of Common Stock, or by a split-up of shares of Common Stock or other similar event, then, on the effective date of such stock dividend, split-up or similar event, the number of shares of Common Stock issuable on exercise of each Public Warrant will be increased in proportion to such increase in the outstanding shares of Common Stock. A rights offering to holders of Common Stock entitling holders to purchase shares of Common Stock at a price less than the fair market value will be deemed a stock dividend of a number of shares of Common Stock equal to the product of (i) the number of shares of Common Stock actually sold in such rights offering (or issuable under any other equity securities sold in such rights offering that are convertible into or exercisable for Common Stock) multiplied by (ii) one minus the quotient of (a) the price per share of Common Stock paid in such rights offering divided by (b) the fair market value. For these purposes (1) if the rights offering is for securities convertible into or exercisable for Common Stock, in determining the price payable for Common Stock, there will be taken into account any consideration received for such rights, as well as any additional amount payable upon exercise or conversion and (2) fair market value means the volume weighted average price of Common Stock as reported during the 10 trading day period ending on the trading day prior to the first date on which the shares of Common Stock trade on the applicable exchange or in the applicable market, regular way, without the right to receive such rights.

In addition, if we, at any time while the Public Warrants are outstanding and unexpired, pay a dividend or make a distribution in cash, securities or other assets to the holders of Common Stock on account of such shares of Common Stock (or other shares of our capital stock into which the Public Warrants are convertible), other than (i) as described above or (ii) certain ordinary cash dividends, then the warrant exercise price will be decreased, effective immediately after the effective date of such event, by the amount of cash and/or the fair market value of any securities or other assets paid on each share of Common Stock in respect of such event.

If the number of outstanding shares of our Common Stock is decreased by a consolidation, combination, reverse stock split or reclassification of shares of Common Stock or other similar event, then, on the effective date of such consolidation, combination, reverse stock split, reclassification or similar event, the number of shares of Common Stock issuable on exercise of each Public Warrant will be decreased in proportion to such decrease in outstanding shares of Common Stock.

Whenever the number of shares of Common Stock purchasable upon the exercise of the Public Warrants is adjusted, as described above, the warrant exercise price will be adjusted by multiplying the warrant exercise price immediately prior to such adjustment by a fraction (x) the numerator of which will be the number of shares of Common Stock purchasable upon the exercise of the Public Warrants immediately prior to such adjustment, and (y) the denominator of which will be the number of shares of Common Stock so purchasable immediately thereafter.

In case of any reclassification or reorganization of the outstanding shares of Common Stock (other than those described above or that solely affects the par value of such shares of Common Stock), or in the case of any merger or consolidation of us with or into another corporation (other than a consolidation or merger in which we are the continuing corporation and that does not result in any reclassification or reorganization of our outstanding shares of Common Stock), or in the case of any sale or conveyance to another corporation or entity of the assets or other property of us as an entirety or substantially as an entirety in connection with which we are dissolved, the holders of the Public Warrants will thereafter have the right to purchase and receive, upon the basis and upon the terms and conditions specified in the Public Warrants and in lieu of the shares of our Common Stock immediately theretofore purchasable and receivable upon the exercise of the rights represented thereby, the kind and amount of shares of stock or other securities or property (including cash) receivable upon such reclassification, reorganization, merger or consolidation, or upon a dissolution following any such sale or transfer, that the holder of the Public Warrants would have received if such holder had exercised their Public Warrants immediately prior to such event. However, if such holders were entitled to exercise a right of election as to the kind or amount of securities, cash or other assets receivable upon such consolidation or merger, then the kind and amount of securities, cash or other assets for which each Public Warrant will become exercisable will be deemed to be the weighted average of the kind and amount received per share by such holders in such consolidation or merger that affirmatively make such election, and if a tender, exchange or redemption offer has been made to and accepted by such holders (other than a tender, exchange or redemption offer made by us in connection with redemption rights held by our stockholders or as a result of the repurchase of shares of Common Stock by us if a proposed initial business combination is presented to our stockholders for approval) under circumstances in which, upon completion of such tender or exchange offer, the maker thereof, together with members of any group (within the meaning of Rule 13d-5(b)(1) under the Securities Exchange Act of 1934, as amended (the Exchange Act) (or any successor rule)) of which such maker is a part, and together with any affiliate or associate of such maker (within the meaning of Rule 12b-2 under the Exchange Act (or any successor rule)) and any members of any such group of which any such affiliate or associate is a part, own beneficially (within the meaning of Rule 13d-3 under the Exchange Act (or any successor rule)) more than 50% of the outstanding shares of Common Stock, the holder of a Public Warrant will be entitled to receive the highest amount of cash, securities or other property to which such holder would actually have been entitled as a stockholder if such warrant holder had exercised the Public Warrant prior to the expiration of such tender or exchange offer, accepted such offer and all of the Common Stock held by such holder had been purchased pursuant to such tender or exchange offer, subject to adjustments (from and after the consummation of such tender or exchange offer) as nearly equivalent as possible to the adjustments provided for in the Warrant Agreement. Additionally, if less than 70% of the consideration receivable by the holders of Common Stock in such a transaction is payable in the form of Common Stock in the successor entity that is listed for trading on a national securities exchange or is quoted in an established over-the-counter market, or is to be so listed for trading or quoted immediately following such event, and if the registered holder of the Public Warrant properly exercises the Public Warrant within 30 days following public disclosure of such transaction, the warrant exercise price will be reduced as specified in the Warrant Agreement based on the per share consideration minus Black-Scholes Warrant Value (as defined in the Warrant Agreement) of the Public Warrant.

The Public Warrants have been issued in registered form under the Warrant Agreement between Continental Stock Transfer & Trust Company, as warrant agent, and us. You should review a copy of the Warrant Agreement, which is filed as an exhibit to Annual Report on Form 10-K to which this Exhibit 4.3 is filed as an exhibit, for a complete description of the terms and conditions applicable to the Public Warrants. The Warrant Agreement provides that the terms of the Public Warrants may be amended without the consent of any holder to cure any ambiguity or correct any defective provision, but requires the approval by the holders of at least 50% of the then outstanding Public Warrants to make any change that adversely affects the interests of the registered holders of Public Warrants.

The Public 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 (or on a cashless basis, if applicable), by certified or official bank check payable to us, for the number of Public Warrants being exercised. The warrant holders do not have the rights or privileges of holders of Common Stock and any voting rights until they exercise their Public Warrants and receive shares of Common Stock. After the issuance of shares of Common Stock upon exercise of the Public Warrants, each holder will be entitled to one vote for each share held of record on all matters to be voted on by stockholders.

Certain Anti-Takeover Provisions of Delaware Law, the Certificate of Incorporation and the Bylaws

Provisions of the DGCL and the Certificate of Incorporation could make it more difficult to acquire our company by means of a tender offer, a proxy contest or otherwise, or to remove incumbent officers and directors. These provisions, summarized below, are intended to discourage coercive takeover practices and inadequate takeover bids and to encourage persons seeking to acquire control of our company to first negotiate with the Board. We believe that the benefits of these provisions outweigh the disadvantages of discouraging certain takeover or acquisition proposals because, among other things, negotiation of these proposals could result in an improvement of their terms and enhance the ability of our Board to maximize stockholder value. However, these provisions may delay, deter or prevent a merger or acquisition of us that a stockholder might consider is in its best interest, including those attempts that might result in a premium over the prevailing market price of the Common Stock.

In addition, the Certificate of Incorporation provides for certain other provisions that may have an anti-takeover effect:

• There is no cumulative voting with respect to the election of directors.

• Our Board is empowered to elect a director to fill a vacancy created by the expansion of the Board or the resignation, death, or removal of a director in certain circumstances.

• Directors may only be removed from the Board for cause.

• Our Board is classified into three classes of directors. As a result, in most circumstances, a person can gain control of our Board by successfully engaging in a proxy contest at two or more annual meetings.

• A prohibition on stockholder action by written consent, which forces stockholder action to be taken at an annual or special meeting of our stockholders.

• A prohibition on stockholders calling a special meeting and the requirement that a meeting of stockholders may only be called by members of our Board, which may delay the ability of our stockholders to force consideration of a proposal or to take action, including the removal of directors.

• Our authorized but unissued Common Stock and preferred stock are available for future issuances without stockholder approval and could be utilized for a variety of corporate purposes, including future offerings to raise additional capital, acquisitions and employee benefit plans. Our Board is entitled, without further stockholder approval, to designate one or more series of preferred stock and the associated voting rights, preferences and privileges of such series of preferred stock. The existence of authorized but unissued and unreserved Common Stock and preferred stock could render more difficult or discourage an attempt to obtain control of us by means of a proxy contest, tender offer, merger or otherwise.

Forum Selection Clause

The Certificate of Incorporation includes a forum selection clause, which provides that, subject to limited exceptions, the Court of Chancery of the State of Delaware and federal court within the State of Delaware will be exclusive forums for any:

• derivative action or proceeding brought on our behalf;

• action asserting a claim of breach of a fiduciary duty owed by, or other wrongdoing by, any director, officer, stockholder, employee or agent of us to us or our stockholders;

• action asserting a claim against us or any director, officer, stockholder, employee or agent of us arising pursuant to any provision of the DGCL, our charter or Bylaws or as to which the DGCL confers jurisdiction on the Court of Chancery of the State of Delaware:

• action to interpret, apply, enforce or determine the validity of our charter or Bylaws; or

• other action asserting a claim against us or any director, officer, stockholder, employee or agent of us that is governed by the internal affairs doctrine.

This choice of forum provision does not apply to actions brought to enforce a duty or liability created by the Exchange Act or any other claim for which federal courts have exclusive jurisdiction. Furthermore, in accordance with the Bylaws, unless we consent in writing to the selection of an alternative forum, the federal district courts of the United States will be, to the fullest extent permitted by law, the exclusive forum for the resolution of any complaint asserting a cause of action arising under the Securities Act. We intend for this provision to apply to any complaints asserting a cause of action under the Securities Act despite the fact that Section 22 of the Securities Act creates concurrent jurisdiction for the federal and state courts over all actions brought to enforce any duty or liability created by the Securities Act or the rules and regulations promulgated thereunder.

Transfer Agent and Warrant Agent

The transfer agent and registrar for our common stock and warrant agent for our warrants is Continental Stock Transfer & Trust Company A. The transfer agent and registrar and warrant agent’s address is 1 State Street, 30th Floor, New York, New York 10004, and its telephone number is  (212) 509-4000.

Listing of Securities

Our Common Stock and Public Warrants are listed on Nasdaq under the symbols “EQRX” and “EQRXW,” respectively.