ERP OPERATING LTD PARTNERSHIP

Item 1.01 Entry into a Material Definitive Agreement. On May 20, 2026, Equity Residential, a Maryland real estate investment trust (“Equity Residential”), and ERP Operating Limited Partnership, an Illinois limited partnership (the “ERP Operating Partnership”), entered into an Agreement and Plan of Merger (the “Merger Agreement”), by and among AvalonBay Communities, Inc., a Maryland corporation (“AvalonBay”), Equity Residential, the ERP Operating Partnership and Canopy Merger Sub LLC, a Maryland limited liability company and a direct wholly owned subsidiary of Equity Residential (“Merger Sub”). Capitalized terms used but not defined herein have the meanings ascribed to them in the Merger Agreement. The Merger Agreement provides for the combination of Equity Residential and AvalonBay in an all-stock merger-of-equals transaction upon the terms and subject to the conditions set forth in the Merger Agreement. The combined company will operate under a new name to be announced prior to the closing of the Transactions (as defined below) (the “closing”). The Board of Trustees of Equity Residential (the “Equity Residential Board”) and the Board of Directors of AvalonBay (the “AvalonBay Board”) have each unanimously approved the Merger Agreement and the Transactions. Upon the terms and subject to the conditions of the Merger Agreement, (i) on the closing date but prior to the Effective Time (as defined below), AvalonBay will contribute certain assets set forth in an exhibit to the Merger Agreement (the “Asset Contribution”) in exchange for units of partnership interest in the ERP Operating Partnership (“OP Units”) that have, in the aggregate, a value equal to the fair market value of such contributed assets and (ii) following the Asset Contribution and at the Effective Time, AvalonBay will merge with and into Merger Sub, with Merger Sub being the surviving entity (the “Merger” and, together with the Asset Contribution and the other transactions contemplated by the Merger Agreement, the “Transactions”). The Equity Residential Board, for itself and in its capacity as the sole general partner of the ERP Operating Partnership, has unanimously (a) determined and declared the Merger Agreement, the Transactions and the issuance of common shares of beneficial interest, $0.01 par value per share, of Equity Residential (the “Equity Residential Common Shares”) in connection with the Merger fair to, advisable and in the best interests of Equity Residential and its shareholders, (b) approved and deemed advisable the execution and delivery of the Merger Agreement, the performance by Equity Residential of its covenants and agreements contained therein and the consummation of the Transactions, (c) directed that the issuance of Equity Residential Common Shares in connection with the Merger be submitted for consideration at a meeting of Equity Residential’s shareholders and (d) resolved to recommend that Equity Residential’s shareholders vote in favor of the approval of (A) the issuance of Equity Residential Common Shares in connection with the Merger and (B) the approval of an amendment to Equity Residential’s Declaration of Trust to increase the number of authorized Equity Residential Common Shares, and to include such recommendation in the Joint Proxy Statement/Prospectus contemplated by the Merger Agreement. Merger Consideration Pursuant to the terms and subject to the conditions in the Merger Agreement, at the effective time of the Merger (the “Effective Time”), by virtue of the Merger, each outstanding share of common stock of AvalonBay, par value $0.01 per share (“AvalonBay Common Stock”), issued and outstanding immediately prior to the Effective Time will automatically be cancelled, retired and will cease to exist, and will be converted into the right to receive 2.793 (the “Exchange Ratio”) Equity Residential Common Shares, plus the right, if any, to receive cash in lieu of fractional Equity Residential Common Shares, if any, into which such AvalonBay Common Stock would have been converted. Post-Closing Governance Equity Residential and AvalonBay have also agreed to certain governance-related matters. At the Effective Time, the Board of Trustees of the combined company will have fourteen members, consisting of (a) seven members of the Equity Residential Board as of immediately prior to the Effective Time, including David J. Neithercut and Stephen E. Sterrett, and (b) seven members of the AvalonBay Board as of immediately prior to the Effective Time, including Timothy J. Naughton and Benjamin W. Schall. In addition, effective as of the Effective Time, Stephen E. Sterrett will be appointed to serve as Chairman of the Board of Trustees of the combined company, and Benjamin W. Schall will be appointed to serve as Chief Executive Officer of the combined company. Treatment of AvalonBay Equity Awards Pursuant to the terms and conditions of the Merger Agreement, as of the Effective Time, each award of restricted shares of AvalonBay Common Stock that vest on the basis of time (each, an “AvalonBay Restricted Share Award”) granted under an AvalonBay equity plan outstanding immediately prior to the Effective Time (subject to certain exceptions), by virtue of the Merger, will be converted into an award of restricted Equity Residential Common Shares that is subject solely to time-based vesting conditions (each, an “Equity Residential Time-Vesting Restricted Share Award”) with respect to a number of Equity Residential Common Shares, rounded to the nearest whole number of shares, equal to the product of (i) the number of shares of AvalonBay Common Stock subject to such AvalonBay Restricted Share Award immediately prior to the Effective Time and (ii) the Exchange Ratio, subject to and in accordance with the terms of the applicable AvalonBay equity plan and AvalonBay Restricted Share Award agreement in effect immediately prior to the Effective Time (including vesting schedule, retirement provisions, double-trigger vesting acceleration entitlements and payment of dividend entitlements). -2- Each award with respect to shares of AvalonBay Common Stock that vest on the basis of the achievement of applicable performance goals (each, an “AvalonBay Performance Award”) granted under an AvalonBay equity plan outstanding immediately prior to the Effective Time, by virtue of the Merger, will be converted into an Equity Residential Time-Vesting Restricted Share Award or an award of OP Units in the ERP Operating Partnership designated as a “Restricted Unit” in the ERP Operating Partnership’s partnership agreement (each, an “Equity Residential Time Vesting Restricted Unit Award”) with respect to a number of Equity Residential Common Shares, rounded to the nearest whole number of shares, equal to the product of (i) the number of shares of AvalonBay Common Stock subject to such AvalonBay Performance Award immediately prior to the Effective Time, determined by deeming any performance-based vesting criteria applicable to such AvalonBay Performance Award to be achieved based on the greater of target performance and the actual level of performance (as calculated as of the latest practicable date prior to the Effective Time and certified by the Compensation Committee of the AvalonBay Board prior to the Effective Time) and (ii) the Exchange Ratio, subject to and in accordance with the terms of the applicable AvalonBay equity plan and form of AvalonBay Restricted Share Award agreement in effect immediately prior to the Effective Time, including the time-based vesting schedule that was associated with that AvalonBay Performance Award but with such other terms as are associated with the form of AvalonBay Restricted Share Award, including retirement provisions and double-trigger vesting acceleration entitlements. Each holder of an AvalonBay Performance Award will also receive a payment in cash equal to cumulative dividends paid by AvalonBay with respect to the shares of AvalonBay Common Stock deemed earned from the date of grant of the AvalonBay Performance Award through the Effective Time. Each award with respect to shares of AvalonBay Common Stock deferred pursuant to the AvalonBay Directors’ Deferred Compensation Plan (each, an “AvalonBay Deferred Unit Award”) outstanding immediately prior to the Effective Time, by virtue of the Merger, will be converted into a number of Equity Residential Common Shares, rounded to the nearest whole number of shares, equal to the product of (i) the number of shares of AvalonBay Common Stock subject to such AvalonBay Deferred Unit Award immediately prior to the Effective Time (inclusive of any dividends paid on shares of AvalonBay Common Stock that have been reinvested and credited in the form of additional AvalonBay Deferred Unit Awards) and (ii) the Exchange Ratio, subject to and in accordance with the terms of the AvalonBay Directors’ Deferred Compensation Plan, in a manner that complies with the requirements of Section 409A (“Section 409A”) of the Internal Revenue Code (the “Code”). Each option to purchase a number of shares of AvalonBay Common Stock at a specific price per share (each, an “AvalonBay Option”) outstanding immediately prior to the Effective Time, by virtue of the Merger, will be converted into an option to purchase a number of Equity Residential Common Shares at a specific price per share (each an “Equity Residential Option”) with respect to a number of Equity Residential Common Shares equal to the product, rounded down to the nearest whole number of shares, of (i) the number of shares of AvalonBay Common Stock subject to such AvalonBay Option immediately prior to the Effective Time and (ii) the Exchange Ratio, and with an exercise price per share, rounded up to the nearest whole cent, equal to (A) the exercise price per share of AvalonBay Common Stock of such AvalonBay Option immediately prior to the Effective Time divided by (B) the Exchange Ratio (each, an “Adjusted Equity Residential Option”). Each Adjusted Equity Residential Option will continue to be subject to the terms of the applicable AvalonBay equity plan and AvalonBay Option award agreement in effect immediately prior to the Effective Time, including the applicable vesting schedule, retirement provisions and double-trigger vesting acceleration entitlements. The exercise price and the number of Equity Residential Common Shares subject to such Adjusted Equity Residential Options will be determined in a manner consistent with the requirements of Section 409A. Treatment of Equity Residential Equity Awards Each Equity Residential Time-Vesting Restricted Share Award, Equity Residential Time-Vesting Restricted Unit Award and Equity Residential Option granted under an Equity Residential equity plan outstanding immediately prior to the Effective Time (subject to certain exceptions) will remain outstanding and continue to be subject to the terms and conditions of the applicable Equity Residential equity plan and individual award agreement in effect immediately prior to the Effective Time, including the applicable vesting schedule, retirement provisions and double-trigger vesting acceleration entitlements. Each award of restricted Equity Residential Common Shares that is subject to both time-based and performance-based vesting conditions (each, an “Equity Residential LTI Restricted Share Award”) and each award of OP Units in the ERP Operating Partnership designated as a “Restricted Unit” in the ERP Operating Partnership’s partnership agreement that is subject to both time-based and performance-based vesting conditions (each, an “Equity Residential LTI Restricted Unit Award”) granted under an Equity Residential equity plan outstanding immediately prior to the Effective Time will be deemed earned, with the applicable performance-based vesting conditions deemed to be achieved based on the greater of target performance and the actual level of performance (as calculated as of the latest practicable date prior to the Effective Time and certified by the Compensation Committee of the Equity Residential Board prior to the Effective Time) and any such earned Equity Residential LTI Restricted Share Award and each Equity Residential LTI Restricted Unit Award will remain outstanding and continue to be subject to the terms and conditions of the applicable Equity Residential equity plan and individual award agreement in effect immediately prior to the Effective Time, including the applicable time-based vesting schedule, retirement provisions and double-trigger vesting acceleration entitlements. All dividend equivalents owed with respect to such earned Equity Residential LTI Restricted Share Awards and earned Equity Residential LTI Restricted Unit Awards will be paid promptly in accordance with applicable award terms. -3- Representations, Warranties and Covenants The Merger Agreement contains representations and warranties from each of Equity Residential and AvalonBay. Additionally, the Merger Agreement provides for pre-closing covenants of each of Equity Residential and AvalonBay, including (i) to use commercially reasonable efforts to carry on their respective businesses in all material respects in the ordinary course, consistent with past practice (subject to certain exceptions); (ii) to hold a meeting of Equity Residential’s shareholders and AvalonBay’s stockholders to obtain the requisite approvals contemplated by the Merger Agreement, as applicable; (iii) not to solicit proposals relating to alternative business combination transactions; and (iv) subject to certain exceptions, not to enter into any discussion concerning, or provide confidential information in connection with, alternative business combination transactions. Closing Conditions The consummation of the Transactions is subject to certain customary closing conditions, including, among others: (i) approval by AvalonBay’s stockholders of the Merger and approval by Equity Residential’s shareholders of the issuance of Equity Residential Common Shares in the Merger; (ii) the absence of a law or order restraining, enjoining, rendering illegal or otherwise prohibiting the consummation of the Merger; (iii) the effectiveness of a registration statement on Form S-4 that will be filed by Equity Residential for the issuance of Equity Residential Common Shares in the Merger; (iv) the authorization of the listing of the Equity Residential Common Shares on the New York Stock Exchange to be issued in the Merger, subject only to official notice of issuance; (v) the accuracy of the representations and warranties of Equity Residential and AvalonBay as of the signing date and as of the closing date (subject to certain qualifications); (vi) material compliance with each party’s covenants; (vii) the receipt by each of Equity Residential and AvalonBay of tax opinions that the Merger will qualify as a “reorganization” within the meaning of Section 368(a) of the Code, (viii) the receipt by Equity Residential of an opinion relating to the status of AvalonBay as a real estate investment trust (“REIT”) under the Code and receipt by AvalonBay of an opinion relating to the status of Equity Residential as a REIT under the Code and (ix) other customary conditions as specified in the Merger Agreement. Termination The Merger Agreement contains provisions granting each of Equity Residential and AvalonBay the right to terminate the Merger Agreement under specified circumstances, including: (i) if the Merger is not completed by May 20, 2027; (ii) if either Equity Residential’s shareholders fail to approve of the share issuance in connection with the Merger or AvalonBay’s stockholders fail to approve the Merger; (iii) if a governmental entity of competent jurisdiction has issued a final, non-appealable order, decree or ruling in each case permanently restraining, enjoining or otherwise prohibiting or making illegal the consummation of the Merger; (iv) if the other party has breached its representations, warranties or covenants in the Merger Agreement, subject to certain conditions; or (v) if the other party’s board has changed its recommendation in connection with the Merger. Upon a termination of the Merger Agreement, under certain circumstances, Equity Residential will be required to pay a termination fee to AvalonBay of the lesser of approximately $1.005 billion or the maximum amount that could be paid to AvalonBay without causing it to fail to meet the REIT requirements for such year. Upon a termination of the Merger Agreement, under certain circumstances, AvalonBay will be required to pay a termination fee to Equity Residential of the lesser of approximately $1.070 billion or the maximum amount that could be paid to Equity Residential without causing it to fail to meet the REIT requirements for such year. Dividends During the term of the Merger Agreement, Equity Residential and AvalonBay may not pay dividends or distributions without the prior written consent of the other party, other than in enumerated instances, including the payment of (i) regular quarterly dividends (x) in respect of AvalonBay Common Stock at a rate not in excess of $1.78 per share, per quarter, and (y) as required to be made in respect of limited partner interests of AvalonBay’s subsidiary partnership structured as a DownREIT, (ii) regular quarterly dividends (x) in respect of Equity Residential Common Shares at a rate not in excess of $0.7025 per share, per quarter, (y) pursuant to the terms of the Equity Residential Series K Preferred Shares and (z) as required to be made in respect of OP Units, and (iii) distributions required for each of Equity Residential and AvalonBay to maintain their respective status as a REIT under the Code or to avoid the incurrence of any entity-level income or excise tax. Equity Residential and AvalonBay also agreed to take such actions as are necessary to ensure that the holders of Equity Residential Common Shares and AvalonBay Common Stock each receive dividends covering the same periods prior to the closing date and to cooperate such that, beginning with the quarterly dividend for the third quarter of 2026, their respective quarterly dividends will have the same record date and payment date. -4- The foregoing description of the Merger Agreement and the Transactions does not purport to be complete and is subject to and qualified in its entirety by reference to the Merger Agreement, a copy of which is attached hereto as Exhibit 2.1 and which is incorporated by reference herein. The Merger Agreement has been included to provide security holders and investors with information regarding its terms. It is not intended to provide any other factual information about Equity Residential, AvalonBay or any other person. The representations, warranties and covenants contained in the Merger Agreement were made solely for purposes of the Merger Agreement and as of specific dates, were solely for the benefit of the parties to the Merger Agreement, may be subject to limitations agreed upon by the contracting parties, including being qualified by confidential disclosures made for the purposes of allocating contractual risk between the parties to the Merger Agreement instead of establishing these matters as facts, and may be subject to standards of materiality applicable to the contracting parties that differ from those applicable to security holders. Security holders and investors are not third-party beneficiaries under the Merger Agreement and should not rely on the representations, warranties and covenants or any descriptions thereof as characterizations of the actual state of facts or condition of Equity Residential or AvalonBay. Moreover, information concerning the subject matter of the representations and warranties may change after the date of the Merger Agreement, which subsequent information may or may not be fully reflected in Equity Residential’s or AvalonBay’s public disclosures.

Item 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers. Amended and Restated Change in Control Agreement with Mr. Parrell On May 20, 2026, the Equity Residential Board approved an Amended and Restated Change in Control Agreement by and between Equity Residential and Mark J. Parrell, which amends and restates the Change in Control Agreement, dated as of March 13, 2009 (the “CIC Agreement”, and such amended and restated agreement, the “Amended CIC Agreement”), effective as of May 20, 2026. Under the Amended CIC Agreement, if Mr. Parrell’s employment is terminated by Equity Residential without cause or by Mr. Parrell for good reason within 36 months following a change in control, he will be entitled to (i) a lump-sum cash severance payment equal to 2.25 times the sum of (a) his base salary and (b) his target annual performance bonus and performance equity grant and (ii) continued medical, dental, life, disability and hospitalization benefits for 27 months following his termination date. This modification aligns Mr. Parrell’s severance formula with that applicable to other executive officers of Equity Residential. The Amended CIC Agreement also provides that, following the conclusion of the 27 month benefits continuation period above, Equity Residential will use commercially reasonable efforts to provide Mr. Parrell with access to comparable medical, dental, life, disability and hospitalization benefits until August 31, 2031 at Mr. Parrell’s expense, or if such access is unavailable, will reimburse the excess cost of obtaining comparable coverage over the total premium applicable to active executives. The foregoing description of the Amended CIC Agreement does not purport to be complete and is subject to and qualified in its entirety by reference to the Amended CIC Agreement, a copy of which will be filed as an exhibit to Equity Residential’s Quarterly Report on Form 10-Q for the second quarter. Offer Letter with Mr. Schall On May 20, 2026, the Equity Residential Board approved and Equity Residential entered into an offer letter with Benjamin W. Schall, confirming his appointment as the Chief Executive Officer of Equity Residential effective as of the closing (the “CEO Offer Letter”). The CEO Offer Letter provides that Mr. Schall’s employment with Equity Residential will commence at closing on the same terms as were applicable to him immediately prior to the closing, including base salary and target cash and equity incentive opportunities. The Equity Residential Board, or a committee thereof, will re-evaluate Mr. Schall’s compensation package at the same time as for other senior executives of Equity Residential. The CEO Offer Letter will automatically terminate if the Merger Agreement is terminated before the closing. The foregoing description of the CEO Offer Letter does not purport to be complete and is subject to and qualified in its entirety by reference to the CEO Offer Letter, a copy of which will be filed as an exhibit to Equity Residential’s Quarterly Report on Form 10-Q for the second quarter.

Item 5.03 Amendment to Articles of Incorporation or Bylaws. On May 20, 2026, the Equity Residential Board unanimously approved an amendment to Equity Residential’s Ninth Amended and Restated Bylaws (the “Bylaws Amendment”) to add a new Article XVI designating the Circuit Court for Baltimore City, Maryland or, if that court does not have jurisdiction, another state or federal court sitting in Maryland, as the exclusive forum for certain legal actions related to Equity Residential. The Bylaws Amendment became effective on May 20, 2026. The foregoing description of the Bylaws Amendment does not purport to be complete and is subject to and qualified in its entirety by reference to the Bylaws Amendment, a copy of which is attached hereto as Exhibit 3.1 and which is incorporated by reference herein. -5-

Item 7.01 Regulation FD Disclosure. On May 21, 2026, Equity Residential and AvalonBay issued a joint press release announcing that they had entered into the Merger Agreement. A copy of the joint press release is attached hereto as Exhibit 99.1 and incorporated by reference herein. Also on May 21, 2026, Equity Residential and AvalonBay released a joint investor presentation. A copy of the joint investor presentation is attached hereto as Exhibit 99.2 and incorporated by reference herein. The information contained in this Item 7.01 on Form 8-K is being furnished and shall not be deemed “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that Section, nor shall it be deemed incorporated by reference in any registration statement or other document filed by Equity Residential under the Securities Act of 1933, as amended (the “Securities Act”), or the Exchange Act, except as otherwise expressly stated in such filing. In addition, the information contained in this Item 7.01 on Form 8-K will not be deemed an admission as to the materiality of any information required to be disclosed solely to satisfy the requirements of Regulation FD.

Item 8.01 Other Events. On May 20, 2026, in connection with the execution of the Merger Agreement, the ERP Operating Partnership entered into a commitment letter (the “Commitment Letter”), with Morgan Stanley Senior Funding, Inc. (“MS”), Wells Fargo Securities, LLC, and Wells Fargo Bank, National Association (“Wells Fargo Bank”), pursuant to which MS and Wells Fargo Bank committed to provide, subject to the terms and conditions of the Commitment Letter, up to $2,000,000,000 of senior unsecured bridge loans.