Exhibit 4.1

Description of Equity Residential Common Shares Registered Under Section 12 of the Securities Exchange Act of 1934

Please note that in this exhibit, references to “the Company,” “we,” “our” and “us” refer to Equity Residential, as the issuer of the Common Shares, unless the context requires otherwise.

The description of the Common Shares of Beneficial Interest, $0.01 par value (the “Common Shares”), of the Company set forth below does not purport to be complete and is subject to and qualified in its entirety by reference to the Articles of Restatement of Declaration of Trust of the Company dated December 9, 2004 (“Declaration of Trust”), as amended and/or restated from time to time, and the Eighth Amended and Restated Bylaws of the Company, as adopted on October 1, 2015 (“Bylaws”), as amended, supplemented and/or restated from time to time, each of which is incorporated by reference as an exhibit to the Annual Report on Form 10-K of which this Exhibit 4.1 is a part. We encourage you to read our Declaration of Trust, our Bylaws, and the applicable provisions of the Maryland REIT Law (as defined below) for additional information.

Our Declaration of Trust provides that we may issue up to 1,000,000,000 Common Shares.

Both Title 8 of the Corporations and Associations Article of the Annotated Code of Maryland (the “Maryland REIT Law”) and our Declaration of Trust provide that no shareholder of the Company will be liable for any debt or obligation of the Company solely as a result of his or her status as a shareholder of the Company. Our Declaration of Trust further provides that the Company has the power to indemnify each shareholder against any claim or liability to which the shareholder may become subject by reason of his or her being or having been a shareholder and to reimburse each shareholder for all reasonable expenses incurred by him or her in connection with any such claim or liability.

The Common Shares are traded on The New York Stock Exchange under the trading symbol of “EQR.”

Distributions

Subject to the preferential rights of any other class of shares of beneficial interest (none of which are currently outstanding other than Series K Cumulative Redeemable Preferred Shares) and to the provisions of our Declaration of Trust regarding excess shares (as defined herein), holders of Common Shares are entitled to receive distributions if, as and when authorized and declared by the Board of Trustees of the Company (the “Board of Trustees”) out of assets legally available therefor and to share ratably in the assets of the Company legally available for distribution to its shareholders in the event of its liquidation, dissolution or winding-up after payment of, or adequate provision for, all known debts and liabilities of the Company. Holders of Common Shares have no right to any dividend or distribution unless and until authorized and declared by the Board of Trustees.

Voting Rights

Subject to the provisions of our Declaration of Trust regarding excess shares, each outstanding Common Share entitles the holder to one vote on the following matters: (a) the election or removal of Trustees; (b) the amendment of our Declaration of Trust; (c) the voluntary dissolution or termination of Equity Residential; (d) the merger of Equity Residential, provided, however, that the shareholders shall not be entitled to vote on a merger of Equity Residential which may be approved pursuant to the provisions of the Maryland REIT Law by a majority of the entire Board of Trustees without a vote of the shareholders and, further provided, that if a shareholder vote is required pursuant to the provisions of the Maryland REIT Law, such merger shall be approved by the affirmative vote of the holders of not less than a majority of all of the shares then outstanding and entitled to vote thereon; (e) the sale or other disposition of all or substantially all of Equity Residential’s assets, provided, however, that the sale or other disposition of all or substantially all of Equity Residential’s assets shall be approved by the affirmative vote of the holders of not less than a majority of all the shares then outstanding and entitled to vote thereon; and (f) such other matters with respect to which the Board of Trustees has adopted a resolution declaring advisable or recommending a proposal and directing that the matter be submitted to the shareholders for consideration. Except as otherwise required by law or except as provided with respect to any other class or series of shares of beneficial interest, the holders of the Common Shares

will possess the exclusive voting power. There is no cumulative voting in the election of Trustees, which means that the holders of a majority of the outstanding Common Shares can elect all of the Trustees then standing for election and the holders of the remaining shares of beneficial interest, if any, will not be able to elect any Trustees.

Under the Maryland REIT Law, a declaration of trust may permit the trustees by a two-thirds vote to amend the declaration of trust from time to time to enable it to qualify as a real estate investment trust (“REIT”) under the Internal Revenue Code of 1986, as amended (the “Internal Revenue Code”), or the Maryland REIT Law without the affirmative vote or written consent of the shareholders. Our Declaration of Trust permits such action by the Board of Trustees.

Conversion, Redemption, Liquidation Rights

Holders of Common Shares have no conversion, sinking fund, redemption or preemptive rights to subscribe for any securities of the Company. Subject to the provisions of our Declaration of Trust regarding excess shares, Common Shares have equal distribution, liquidation and other rights, and have no preference, exchange or, except as expressly required by the Maryland REIT Law, appraisal rights.

Restriction on Ownership and Transfer

For the Company to qualify as a REIT under the Internal Revenue Code, no more than 50% in value of its outstanding shares of beneficial interest may be owned, actually or constructively, by five or fewer individuals (as defined in the Internal Revenue Code to include certain entities) during the last half of a taxable year (other than the first year for which an election to be treated as a REIT has been made) or during a proportionate part of a shorter taxable year. A REIT’s shares also must be beneficially owned by 100 or more persons during at least 335 days of a taxable year of twelve months or during a proportionate part of a shorter taxable year (other than the first year for which an election to be treated as a REIT has been made). To facilitate maintenance of its qualification as a REIT for federal income tax purposes, we generally will prohibit ownership, directly or by virtue of the attribution provisions of the Internal Revenue Code, by any single shareholder of more than 5% (in value or number of shares, whichever is more restrictive) of the issued and outstanding Common Shares (the “Ownership Limit”).

Because the Board of Trustees believes it is desirable for the Company to qualify as a REIT, the Declaration of Trust, subject to certain exceptions, provides that no holder may own, or be deemed to own by virtue of the attribution provisions of the Internal Revenue Code, more than the Ownership Limit. The ownership attribution rules under the Internal Revenue Code are complex and may cause Common Shares owned actually or constructively by a group of related individuals and/or entities to be owned constructively by one individual or entity. As a result, the acquisition of less than 5% of the Common Shares (or the acquisition of an interest in an entity that owns, actually or constructively, Common Shares) by an individual or entity could nevertheless cause that individual or entity, or another individual or entity, to own constructively in excess of 5% of the outstanding Common Shares and thus subject such Common Shares to the Ownership Limit. To reduce the ability of the Board of Trustees to use the Ownership Limit as an anti-takeover device, the Declaration of Trust requires, rather than permits, the Board of Trustees to grant a waiver of the Ownership Limit if the shareholder seeking a waiver demonstrates that such ownership would not jeopardize the Company’s status as a REIT. We have issued several of these waivers in the past. As a condition of such a waiver, the Board of Trustees may require undertakings or representations from the shareholder seeking a waiver with respect to preserving the REIT status of the Company.

The Board of Trustees will have the authority to increase the Ownership Limit from time to time, but will not have the authority to do so to the extent that after giving effect to such increase, five persons who would be treated as “individuals” for purposes of the Internal Revenue Code could beneficially own in the aggregate more than 49.5% of the outstanding Common Shares.

The Declaration of Trust further prohibits (a) any person from actually or constructively owning shares of beneficial interest of the Company that would result in the Company being “closely held” under Section 856(h) of the Internal Revenue Code or otherwise cause the Company to fail to qualify as a REIT and (b) any person from transferring shares of beneficial interest of the Company if such transfer would result in shares of beneficial interest of the Company being owned by fewer than 100 persons.

Any person who acquires or attempts or intends to acquire actual or constructive ownership of shares of beneficial interest of the Company that will or may violate any of the foregoing restrictions on transferability and ownership is required to give at least 15 days’ prior written notice to the Company and provide the Company with such other information as the Company may request in order to determine the effect of such transfer on the Company’s status as a REIT.

If any purported transfer of shares of beneficial interest of the Company or any other event would otherwise result in any person violating the Ownership Limit or the other restrictions in the Declaration of Trust, then any such purported transfer will be void and of no force or effect with respect to the purported transferee (the “Prohibited Transferee”) as to that number of shares that exceeds the Ownership Limit (referred to as “excess shares”) and the Prohibited Transferee shall acquire no right or interest (or, in the case of any event other than a purported transfer, the person or entity holding record title to any such shares in excess of the Ownership Limit (the “Prohibited Owner”) shall cease to own any right or interest) in such excess shares. Any such excess shares described above will be transferred automatically, by operation of law, to a trust, the beneficiary of which will be a qualified charitable organization selected by the Company (the “Beneficiary”). Such automatic transfer shall be deemed to be effective as of the close of business on the Business Day (as defined in the Declaration of Trust) prior to the date of such violating transfer. Within 20 days of receiving notice from the Company of the transfer of shares to the trust, the trustee of the trust (who shall be designated by the Company and be unaffiliated with the Company and any Prohibited Transferee or Prohibited Owner) will be required to sell such excess shares to a person or entity who could own such shares without violating the Ownership Limit, and distribute to the Prohibited Transferee an amount equal to the lesser of the price paid by the Prohibited Transferee for such excess shares or the sales proceeds received by the trust for such excess shares. In the case of any excess shares resulting from any event other than a transfer, or from a transfer for no consideration (such as a gift), the trustee will be required to sell such excess shares to a qualified person or entity and distribute to the Prohibited Owner an amount equal to the lesser of the fair market value of such excess shares as of the date of such event or the sales proceeds received by the trust for such excess shares. In either case, any proceeds in excess of the amount distributable to the Prohibited Transferee or Prohibited Owner, as applicable, will be distributed to the Beneficiary. Prior to a sale of any such excess shares by the trust, the trustee will be entitled to receive, in trust for the Beneficiary, all dividends and other distributions paid by the Company with respect to such excess shares, and also will be entitled to exercise all voting rights with respect to such excess shares. Subject to Maryland law, effective as of the date that such shares have been transferred to the trust, the trustee shall have the authority (at the trustee’s sole discretion and subject to applicable law) (i) to rescind as void any vote cast by a Prohibited Transferee prior to the discovery by the Company that such shares have been transferred to the trust and (ii) to recast such vote in accordance with the desires of the trustee acting for the benefit of the Beneficiary. However, if the Company has already taken irreversible corporate action, then the trustee shall not have the authority to rescind and recast such vote. Any dividend or other distribution paid to the Prohibited Transferee or Prohibited Owner (prior to the discovery by the Company that such shares had been automatically transferred to a trust as described above) will be required to be repaid to the trustee upon demand for distribution to the Beneficiary. If the transfer to the trust as described above is not automatically effective (for any reason) to prevent violation of the Ownership Limit, then the Declaration of Trust provides that the transfer of the excess shares will be void.

In addition, shares of beneficial interest of the Company held in the trust shall be deemed to have been offered for sale to the Company, or its designee, at a price per share equal to the lesser of (i) the price per share in the transaction that resulted in such transfer to the trust (or, in the case of a devise or gift, the market value at the time of such devise or gift) and (ii) the market value of such shares on the date the Company, or its designee, accepts such offer. The Company shall have the right to accept such offer until the trustee has sold the shares of beneficial interest held in the trust. Upon such a sale to the Company, the interest of the Beneficiary in the shares sold shall terminate and the trustee shall distribute the net proceeds of the sale to the Prohibited Owner.

The foregoing restrictions on transferability and ownership will not apply if the Board of Trustees determines that it is no longer in the best interests of the Company to attempt to qualify, or to continue to qualify, as a REIT.

All persons who own, directly or by virtue of the attribution provisions of the Internal Revenue Code, more than 5% (or such lower percentage as provided in the rules and regulations promulgated under the Internal Revenue Code) of the outstanding shares of beneficial interest of the Company must give a written notice to the Company within 30 days after the end of each taxable year stating such person’s name and address, the number of shares owned by such person and a description of the manner in which such shares are held. Any record holder who holds shares as nominee for

another person who is required to include in gross income the distributions received on such shares must give notice stating the name and address of such other person and the number of shares of such other person with respect to which such record holder is nominee. In addition, each shareholder will, upon demand, be required to disclose to the Company in writing such information with respect to the direct, indirect and constructive ownership of shares of beneficial interest as the Board of Trustees deems reasonably necessary to comply with the provisions of the Internal Revenue Code applicable to a REIT or to ensure compliance with the ownership limitations described above.

These ownership limitations could have the effect of delaying, deferring or preventing a takeover or other transaction in which holders of some, or a majority, of Common Shares might receive a premium for their Common Shares over the then prevailing market price or which such holders might believe to be otherwise in their best interest.

Registrar and Transfer Agent

The registrar and transfer agent for the Common Shares is Computershare Trust Company, N.A.

Possible Anti-Takeover Effects of Maryland Law and our Declaration of Trust and Bylaws

The business combination provisions of Maryland law (with the exception that such provisions do not apply to transactions involving certain of Samuel Zell’s (our former Chairman of the Board of Trustees) affiliates and persons acting in concert with them), the control share acquisition provisions of Maryland law (if the applicable provision in our Bylaws is rescinded), the exclusive power of the Trustees to fill vacancies on the Board of Trustees and the provision that any Trustee so appointed will serve for the remaining term of that trusteeship, the limitations on removal of Trustees, the power of the Board of Trustees to issue Preferred Shares (and the power to classify any unissued Preferred Shares and reclassify any previously classified but unissued Preferred Shares), the shareholders’ limited ability to call a special meeting, the advance notice provisions of our Bylaws (to the extent not mitigated by the proxy access provision) and the restrictions on the acquisition of our shares could have the effect of delaying, deterring or preventing a transaction or a change in control of our Company that might involve a premium price for holders of Common Shares or that shareholders otherwise believe may be in their best interest. The “unsolicited takeovers” provisions of Maryland law permit the Board of Trustees, without shareholder approval and regardless of what is provided in our Declaration of Trust or Bylaws, to implement takeover defenses that we may not yet have.