Exhibit 4.3

DESCRIPTION OF COMMON STOCK

General

The following description summarizes the most important terms of our common stock. Because it is only a summary, it does not contain all the information that may be important to you. For a complete description of the matters set forth in this “Description of Common Stock,” you should refer to our amended and restated certificate of incorporation, as amended (the “Restated Certificate”), and amended and restated bylaws (the “Restated Bylaws”), which are included as exhibits to our Annual Report on Form 10-K, and to the applicable provisions of Delaware law. Our authorized capital stock consists of 225,000,000 shares of common stock, $0.0001 par value per share, and 5,000,000 shares of undesignated preferred stock, $0.0001 par value per share. Our board of directors is authorized, without stockholder approval except as required by the listing standards of The Nasdaq Stock Market LLC, to issue additional shares of our capital stock.  In addition, our board of directors may, without further action by our stockholders, designate the rights, preferences, privileges, and restrictions of our preferred stock in one or more series.

Voting Rights

Each holder of our common stock is entitled to one vote for each share of common stock held on all matters submitted to a vote of stockholders, except as otherwise expressly provided in our Restated Certificate or required by applicable law. Our Restated Certificate does not provide for cumulative voting for the election of directors.

Dividends and Distributions 

Subject to the prior rights of holders of all classes and series of stock at the time outstanding having prior rights as to dividends, the holders of common stock are entitled to receive, when, as and if declared by the board of directors, out of any assets legally available therefor, such dividends as may be declared from time to time by the board of directors.

Other 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.

Transfer Agent and Registrar

Computershare Trust Company, N.A. serves as the registrar and transfer agent for our common stock.

Stock Exchange Listing

Our common stock is listed on The Nasdaq Global Select Market under the trading symbol “ACAD”.

Anti-Takeover Provisions

Delaware 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:

In general, Section 203 defines business combination to include the following:

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 Provisions

Because our stockholders do not have cumulative voting rights, our stockholders holding a majority of the voting power of our shares of common stock outstanding are able to elect all of our directors. Our Restated Certificate and Restated Bylaws provide that all stockholder actions must be effected at a duly called meeting of stockholders and not by written consent or electronic transmission. A special meeting of stockholders may be called by the majority of our whole board of directors, the Chairman of the board of directors, or our chief executive officer.

In accordance with our Restated Certificate, our board of directors is divided into three classes with staggered three-year terms.

In addition, our Restated Certificate and Restated Bylaws provide that the number of directors constituting our board of directors may be set only by a resolution adopted by our entire board of directors, and that (i) subject to the rights of any series of preferred stock to elect directors, neither our board of directors nor any individual director may be removed without cause, and (ii) subject to any limitation imposed by law, any individual director or directors may be removed with cause by the affirmative vote of the holders of a majority of the voting power of all then-outstanding shares of the capital stock entitled to vote generally at an election of directors. Our Restated Certificate and Restated Bylaws also provide that vacancies occurring on our board of directors and newly created directorships resulting from an increase in the authorized number of directors may be filled only by vote of a majority of the remaining members of our board of directors, even though less than a quorum. Our Restated Certificate and Restated Bylaws provide that our board of directors is expressly authorized to adopt, amend, or repeal our bylaws, and require the affirmative vote of the holders of at least 66 2/3% of the voting power of all of the then-outstanding shares of the capital stock entitled to vote generally in the election of directors, voting together as a single class, to amend our Restated Bylaws and certain provisions of our Restated Certificate.

Our Restated 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 our annual meeting of stockholders. Our Restated Bylaws also specify certain requirements regarding the form and content of a stockholder’s notice. These provisions might preclude our stockholders from bringing matters before our annual meeting of stockholders or from making nominations for directors at our annual meeting of stockholders if the proper procedures are not followed. We expect that these provisions may also discourage or deter a potential acquirer from conducting a solicitation of proxies to elect the acquirer’s own slate of directors or otherwise attempting to obtain control of our company.

The foregoing provisions may 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. Since 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 certain types of transactions that may involve an actual or threatened acquisition of us. These provisions are also designed to reduce our vulnerability to an unsolicited acquisition proposal 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 deterring hostile takeovers or delaying changes in our control or management. As a consequence, these provisions also may inhibit fluctuations in the market price of our stock that could result from actual or rumored takeover attempts.

Choice of Forum

Our Restated Bylaws provide that, unless we consent in writing to the selection of an alternative forum, the Court of Chancery of the State of Delaware shall be the sole and exclusive forum for (i) any derivative action or proceeding brought on our behalf; (ii) any action asserting a claim of breach of fiduciary duty owed by any director, officer or other employee of the corporation to the corporation or the corporation’s stockholders; (iii) any action asserting a claim against us arising pursuant to the Delaware General Corporation Law; or (iv) 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. This choice of forum provision does not apply to suits brought to enforce a duty or liability created by the Securities Act of 1933, as amended, or the Securities Exchange Act of 1934, as amended, or any other claim for which the federal courts have exclusive jurisdiction.