Form 424B3 People's United Financia

Filed Pursuant to Rule 424(b)(3)
Registration No. 333-233229

MERGER PROPOSED—YOUR VOTE IS VERY IMPORTANT

September 6, 2019

Dear Shareholder:

On July 15, 2019, United Financial Bancorp, Inc. (which we refer to as “United Financial”) entered into an Agreement and Plan of Merger (which we refer to as the “merger agreement”) with People’s United Financial, Inc. (which we refer to as “People’s United”). Under the merger agreement, United Financial will merge with and into People’s United, with People’s United as the surviving corporation, in a transaction that we refer to as the “merger.” Following the merger, United Financial’s wholly owned subsidiary, United Bank, will merge with and into People’s United’s wholly owned subsidiary, People’s United Bank, National Association, with People’s United Bank, National Association as the surviving bank.

Under the terms and conditions of the merger agreement, each outstanding share of United Financial common stock, no par value (which we refer to as “United Financial common stock”), held immediately prior to the merger, except for specified shares of United Financial common stock owned by United Financial or People’s United (which will be cancelled), will be converted into the right to receive 0.875 shares (which we refer to as the “merger consideration”) of People’s United common stock, par value $0.01 per share (which we refer to as “People’s United common stock”). The value of the merger consideration will depend on the market price of People’s United common stock on the effective date of the merger.

United Financial’s shareholders should obtain current market price quotations for shares of United Financial common stock and shares of People’s United common stock. Shares of United Financial common stock are listed on the NASDAQ Global Select Market under the symbol “UBNK”. Shares of People’s United common stock are (and those shares to be issued as merger consideration will be) listed on the NASDAQ Global Select Market under the symbol “PBCT”. We expect that upon completion of the transactions contemplated by the merger agreement, former United Financial’s shareholders will own approximately 10.1% of the outstanding People’s United common stock (based on the number of shares of United Financial common stock outstanding as of August 27, 2019, the record date for the special meeting, and the number of shares of People’s United common stock outstanding as of such date).

The market value of People’s United common stock being issued as merger consideration will depend on the market price of People’s United common stock on the closing date of the merger. Based on the closing price of People’s United common stock on July 15, 2019, the last trading day before the public announcement of the execution of the merger agreement, the value of the per share consideration payable to United Financial’s shareholders was $14.53. Based on the closing price of People’s United common stock on August 30, 2019, the last practicable date before the filing of the proxy statement/prospectus accompanying this notice, the value of the per share consideration payable to United Financial’s shareholders was $12.57.

United Financial will be holding a special meeting of its shareholders (which we refer to as the “special meeting”) for the purpose of voting on certain matters in connection with the merger on October 22, 2019 at 10:00 a.m., local time, at the Connecticut Science Center, 250 Columbus Boulevard, Hartford, Connecticut 06103. No vote of People’s United’s shareholders is required in connection with the merger, nor is any such vote being sought.

The United Financial board of directors has determined that the merger agreement and the merger are in the best interests of United Financial and its shareholders, has unanimously approved and adopted the merger agreement and the merger and recommends that you vote “FOR” the merger proposal and “FOR” each of the other proposals described in the accompanying proxy statement/prospectus.

Your vote is important, regardless of the number of shares you own. Whether or not you plan to attend the special meeting, please vote as soon as possible to make sure that your shares of United Financial common stock are represented. Submitting a proxy now will not prevent you from being able to vote in person at the special meeting.

The attached proxy statement/prospectus, which serves as the proxy statement for the special meeting of the shareholders of United Financial and the prospectus for the shares of People’s United common stock to be issued in the merger, includes detailed information about the special meeting, the merger and the documents related to the merger. We urge you to read the entire proxy statement/prospectus carefully, including the discussion of the risks related to the merger and owning People’s United common stock after the merger in the section titled “Risk Factors” beginning on page 23. You can also obtain information about United Financial and People’s United from documents that have been filed with the Securities and Exchange Commission that are incorporated into this proxy statement/prospectus by reference.

Sincerely,

William H. W. Crawford, IV

President and Chief Executive Officer

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of the securities to be issued in the merger or passed upon the adequacy or accuracy of this proxy statement/prospectus. Any representation to the contrary is a criminal offense.

The shares of People’s United common stock to be issued in connection with the merger are not savings accounts, deposits or other obligations of any bank or savings association and are not insured by the Federal Deposit Insurance Corporation or any other governmental agency.

This proxy statement/prospectus is dated September 6, 2019, and is first being mailed to United Financial’s shareholders on or about September 6, 2019.

NOTICE OF SPECIAL MEETING OF SHAREHOLDERS

September 6, 2019

To the shareholders of United Financial Bancorp, Inc.:

Notice is hereby given that a special meeting of shareholders (which we refer to as the “special meeting”) of United Financial Bancorp, Inc., a Connecticut corporation (which we refer to as “United Financial”), will be held at the Connecticut Science Center, 250 Columbus Boulevard, Hartford, Connecticut 06103 on October 22, 2019 at 10:00 a.m., local time, for the purpose of considering and voting upon the following matters:

United Financial will transact no other business at the special meeting except for business properly brought before the special meeting or any adjournment or postponement thereof.

United Financial’s board of directors has fixed the close of business on August 27, 2019 as the record date for determination of shareholders entitled to notice of and to vote at the special meeting, and only shareholders of record on said date will be entitled to receive notice of and to vote at such meeting and any adjournments or postponements thereof.

The affirmative vote of the holders of at least two-thirds of the outstanding shares of United Financial common stock is required to approve the merger proposal. Assuming a quorum is present, the affirmative vote of the holders of a majority of the shares of United Financial common stock represented at the special meeting, either in person or by proxy, is required to approve the compensation proposal and the adjournment proposal.

United Financial’s board of directors has unanimously approved and adopted the merger agreement and the transactions contemplated thereby and recommends that you vote “FOR” the merger proposal, “FOR” the compensation proposal and “FOR” the adjournment proposal.

Your vote is very important. Whether or not you plan to attend the special meeting, please take the time to vote by completing, signing, dating and returning the enclosed proxy card to United Financial in the enclosed postage-paid envelope or by submitting a proxy through the Internet or by telephone as described on the enclosed instructions as soon as possible to make sure your shares of United Financial common stock are represented at the special meeting. If you submit a properly signed proxy card without indicating how you want to vote, your proxy will be counted as a vote “FOR” the merger proposal, “FOR” the compensation proposal and “FOR” the adjournment proposal. The failure to vote by not submitting your proxy or not attending the special meeting and voting in person will have the same effect as a vote “AGAINST” the merger proposal. Submitting a proxy now will NOT prevent you from being able to vote in person at the special meeting. If you hold your shares of United Financial common stock in “street name,” through a bank, broker or other nominee, you should instruct your bank, broker or other nominee how to vote in accordance with the voting instruction form you receive from your bank, broker or other nominee.

If you have any questions or need assistance with voting, please contact our proxy solicitor Morrow Sodali LLC, by calling toll free at (800) 662-5200.

By Order of the Board of Directors,

Marliese L. Shaw

Corporate Secretary

ADDITIONAL INFORMATION

The accompanying proxy statement/prospectus incorporates by reference important business and financial information about People’s United and United Financial from documents filed with the Securities and Exchange Commission (which we refer to as the “SEC”) that are not included in or delivered with the proxy statement/prospectus. You can obtain any of the documents filed with or furnished to the SEC by People’s United or United Financial at no cost from the SEC’s website at http://www.sec.gov. You will also be able to obtain these documents, free of charge, from People’s United at www.peoples.com (“Investor Relations” tab under the heading “Financial Information” and under the subheading “Regulatory Filings”) or from United Financial at www.unitedfinancialinc.com (“Investor Relations” heading under the tab “SEC Filings” and tab “Documents”). Additionally, you may also request copies of these documents, including documents incorporated by reference into the proxy statement/prospectus, at no cost upon written or oral request by contacting the appropriate company at the following addresses and telephone numbers:

You will not be charged for any of these documents that you request. To obtain timely delivery of these documents, please do so by October 15, 2019, in order to receive them before the special meeting.

For a more detailed description of the information incorporated by reference into the accompanying proxy statement/prospectus and how you may obtain it, see “Where You Can Find More Information” beginning on page 121 of the accompanying proxy statement/prospectus. The accompanying proxy statement/prospectus provides a detailed description of the merger and the merger agreement. We urge you to read the accompanying proxy statement/prospectus, including any documents incorporated by reference into the accompanying proxy statement/prospectus, and its annexes carefully and in their entirety.

If you have any questions concerning the merger, the other matters to be considered at the special meeting or the accompanying proxy statement/prospectus or need assistance voting your shares of United Financial common stock, please contact United Financial’s proxy solicitor at the address or telephone number listed below:

Morrow Sodali LLC

470 West Avenue

Stamford, CT 06902

Please do not send your stock certificates at this time. You will be sent separate instructions regarding the surrender of your stock certificates.

You should rely only on the information contained in, or incorporated by reference into, the proxy statement/prospectus. No one has been authorized to provide you with information that is different from that contained in, or incorporated by reference into, the proxy statement/prospectus. The proxy statement/prospectus is dated September 6, 2019, and you should assume that the information in the proxy statement/prospectus is accurate only as of such date unless the information specifically indicates that another date applies.

The proxy statement/prospectus does not constitute an offer to sell, or a solicitation of an offer to buy, any securities, or the solicitation of a proxy, in any jurisdiction in which or from any person to whom it is unlawful to make any such offer or solicitation in such jurisdiction.

Table of Contents

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QUESTIONS AND ANSWERS ABOUT THE MERGER AND THE SPECIAL MEETING

The following questions and answers are intended to address briefly some commonly asked questions regarding the merger and the special meeting. These questions and answers may not address all questions that may be important to you as a shareholder. To better understand these matters, and for a description of the legal terms governing the merger, you should carefully read this entire proxy statement/prospectus, including the annexes, as well as the documents that have been incorporated by reference into this proxy statement/prospectus.

This proxy statement/prospectus contains important information about the merger, the merger agreement, the special meeting and other related matters, and you should read it carefully. The enclosed voting materials for the special meeting allow you to vote your shares of United Financial common stock, no par value (which we refer to as “United Financial common stock”), without attending the special meeting in person. Your vote is important, and we encourage you to submit your proxy as soon as possible.

The merger proposal must be approved in order to complete the merger. The approval of the compensation proposal and the adjournment proposal are not conditions to the completion of the merger.

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For more information, see “The Merger Agreement—Conditions to Complete the Merger” beginning on page 101.

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If you hold shares of United Financial common stock in your own name and submit a proxy but fail to provide voting instructions or abstain on any of the proposals listed on the proxy card, your shares will be counted for purposes of determining whether a quorum is present at the special meeting.

If your shares of United Financial common stock are held in “street name” by your broker, bank or other nominee and you do not tell the nominee how to vote your shares, your shares will not be counted for purposes of determining whether a quorum is present for the transaction of business at the special meeting.

Compensation proposal:

Adjournment proposal:

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If you intend to submit your proxy through the Internet or by telephone, you must do so by 11:59 p.m. Eastern Time on October 21, 2019, the day before the special meeting. If you intend to submit your proxy by mail, your completed proxy card must be received prior to the special meeting.

If you hold your shares of United Financial common stock in “street name” through a bank, broker or other nominee, you must direct your bank, broker or other nominee how to vote in accordance with the instructions you have received from your bank, broker or other nominee.

If you hold shares of United Financial common stock in your plan account under the United Bank 401(k) Plan (which we refer to as the “United 401(k) Plan”), including the employee stock ownership plan component of the United 401(k) Plan (which we refer to as the “ESOP”), you will have received voting instruction forms that reflect all shares of United Financial common stock for which you may direct the voting under the plan. Under the terms of the United 401(k) Plan, the United 401(k) Plan trustee votes all shares of United Financial common stock held by the United 401(k) Plan, but each participant may provide instructions to the trustee on how to vote the shares of United Financial common stock held in his or her plan account. The United 401(k) Plan trustee will vote your shares of United Financial common stock in accordance with your instructions and, subject to the exercise of its fiduciary responsibilities, will vote all unallocated shares of United Financial common stock held by the United 401(k) Plan and allocated shares of United Financial common stock for which no voting instructions were received in the same proportion as the instructions received from other participants in the United 401(k) Plan. The deadline for returning your voting instructions is 11:59 p.m. on October 17, 2019.

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You should send any written notice of revocation or any duly executed new proxy, as the case may be, to United Financial at the following address:

United Financial Bancorp, Inc.

225 Asylum Street

Hartford, Connecticut 06103

Attn: Marliese L. Shaw, Corporate Secretary

If you hold your shares of United Financial common stock in “street name” through a bank, broker or other nominee, you must contact your record holder to change your vote.

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If you sign and return your proxy card without indicating how to vote on any particular proposal, the shares of United Financial common stock represented by your proxy will be voted as recommended by United Financial’s board of directors with respect to that proposal, as the case may be.

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RISK FACTORS

In addition to the general investment risks and the other information contained in or incorporated by reference into this proxy statement/prospectus, including the matters addressed under the caption “Information Regarding Forward-Looking Statements” beginning on page 31, you should carefully consider the following risk factors in deciding how to vote on the proposals presented in this proxy statement/prospectus. You should also consider the other information in this proxy statement/prospectus and the other documents incorporated by reference into this proxy statement/prospectus. For more information, see “Where You Can Find More Information” beginning on page 121.

Risks Related to the Merger and People’s United’s Business upon Completion of the Merger

Because the market price of People’s United common stock will fluctuate, United Financial’s shareholders cannot be certain of the market value of the merger consideration they will receive.

Upon completion of the merger, each outstanding share of United Financial common stock held immediately prior to the effective time of the merger, except for shares of United Financial common stock owned by United Financial or People’s United (in each case other than shares of United Financial common stock (1) held in any United Financial benefit plans (other than the United 401(k) Plan, including the ESOP) or trust accounts, managed accounts, mutual funds and the like or otherwise held in a fiduciary or agency capacity, or (2) held, directly or indirectly, in respect of debts previously contracted) (which will be cancelled), will be converted into the right to receive the merger consideration. The market value of the People’s United common stock to be issued in the merger will depend upon the market price of People’s United common stock and of United Financial common stock. The market value of People’s United common stock and United Financial common stock at the effective time of the merger may vary significantly from their respective values on the date the merger was announced or at other dates, including on the date that this proxy statement/prospectus was mailed to United Financial’s shareholders and on the date of the United Financial special meeting. There will be no adjustment to the merger consideration for changes in the market price of either shares of People’s United common stock or United Financial common stock.

The market price of People’s United common stock and United Financial common stock may result from a variety of factors, including, but not limited to, changes in sentiment in the market regarding People’s United’s and United Financial’s operations or business prospects, including regarding People’s United’s and/or United Financial’s entry into the merger agreement. These risks may also be affected by:

Many of these factors are outside the control of People’s United and United Financial. Accordingly, at the time of the United Financial special meeting, United Financial’s shareholders will not necessarily know or be able to

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calculate the value of the merger consideration they would be entitled to receive upon completion of the merger. You should obtain current market quotations for both People’s United common stock and United Financial common stock.

The market price of People’s United common stock after the merger may be affected by factors different from those affecting the shares of People’s United or United Financial currently.

The businesses of People’s United and United Financial differ, and accordingly, the results of operations of the combined company and the market price of the shares of People’s United’s common stock after the completion of the merger may be affected by factors different from those currently affecting the independent results of operations and market prices of common stock of each of People’s United and United Financial. For a discussion of the businesses of People’s United and United Financial and of certain factors to consider in connection with those businesses, see the documents incorporated by reference into this proxy statement/prospectus and referred to under “Where You Can Find More Information” beginning on page 121.

The success of the merger and integration of People’s United and United Financial will depend on a number of uncertain factors.

The success of the merger will depend on a number of factors, including:

Integrating the acquired branches will be an operation of substantial size and expense and may be affected by general market and economic conditions or government actions affecting the financial industry generally. Integration efforts will also likely divert People’s United’s management’s attention and resources. No assurance can be given that People’s United will be able to integrate the acquired branches successfully. Additionally, no assurance can be given that the operation of the acquired branches will not adversely affect People’s United’s existing profitability, that People’s United will be able to achieve results in the future similar to those achieved by its existing banking business or that People’s United will be able to manage any growth resulting from the merger effectively.

Regulatory approvals may not be received, may take longer than expected, may delay the date of completion of the merger or may impose conditions that are not presently anticipated or cannot be met and that could have an adverse effect on People’s United.

Before the transactions contemplated in the merger agreement can be completed, various approvals must be obtained from the bank regulatory and other governmental authorities. In deciding whether to grant these approvals, the relevant governmental entities will consider a variety of factors, including the regulatory standing of each of the parties, the effect of the merger on competition, and the factors described in the section of this proxy statement/prospectus entitled “The Merger—Regulatory Approvals Required for the Merger” beginning on

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page 121. An adverse development in either party’s regulatory standing or other factors could result in an inability to obtain one or more of the required regulatory approvals or delay receipt of required approvals. In addition, the Federal Reserve Board has stated that if supervisory issues arise during the processing of an application for approval of a merger transaction, a banking organization will be expected to withdraw its application pending resolution of such supervisory concerns. No assurance can be given that the OCC or the Connecticut DOB would not also require a similar withdrawal of an application if supervisory issues arise during processing of an application for approval of a bank merger transaction. Accordingly, if there is an adverse development in either party’s regulatory standing, People’s United or People’s United Bank may be required to withdraw its application for approval of the proposed merger and the bank merger, as applicable, and, if possible, resubmit such application after the applicable supervisory concerns have been resolved.

The terms of the approvals that are granted may impose conditions, limitations, obligations or costs, or place restrictions on the conduct of the combined company’s business or require changes to the terms of the transactions contemplated by the merger agreement. There can be no assurance that regulators will not impose any such conditions, limitations, obligations or restrictions and that such conditions, limitations, obligations or restrictions will not have the effect of delaying the completion of any of the transactions contemplated by the merger agreement, imposing additional material costs on or materially limiting the revenues of the combined company following the merger or otherwise reduce the anticipated benefits of the merger if the merger were consummated successfully within the expected timeframe. Nor can there be any assurance that any such conditions, terms, obligations or restrictions will not result in the delay or abandonment of the merger. Additionally, the completion of the merger is conditioned on the absence of certain orders, injunctions or decrees by any court or regulatory agency of competent jurisdiction that would prohibit or make illegal the completion of any of the transactions contemplated by the merger agreement.

People’s United and United Financial believe that the proposed transactions should not raise significant regulatory concerns and that People’s United will be able to obtain all requisite regulatory approvals in a timely manner. However, the processing time for obtaining regulatory approvals for mergers of banking institutions, particularly for larger institutions, has increased since the financial crisis of 2007-2008. In addition, despite the parties’ commitments to use their reasonable best efforts to comply with conditions imposed by regulatory entities, under the terms of the merger agreement, People’s United will not be required and United Financial will not be permitted to take actions that would reasonably be expected to have a material adverse effect on People’s United and its subsidiaries, taken as a whole, after giving effect to the merger (measured on a scale relative to United Financial and its subsidiaries, taken as a whole). See “The Merger—Regulatory Approvals Required for the Merger” beginning on page 83.

Combining People’s United and United Financial may be more difficult, costly or time consuming than expected and the anticipated benefits and cost savings of the merger may not be realized.

People’s United and United Financial have operated and, until the completion of the merger, will continue to operate, independently. The success of the merger, including anticipated benefits and cost savings, will depend, in part, on People’s United’s ability to successfully combine and integrate the businesses of People’s United and United Financial in a manner that permits growth opportunities and does not materially disrupt existing customer relations nor result in decreased revenues due to loss of customers. It is possible that the integration process could result in the loss of key employees, the disruption of either company’s ongoing businesses or inconsistencies in standards, controls, procedures and policies that adversely affect the combined company’s ability to maintain relationships with clients, customers, depositors and employees or to achieve the anticipated benefits and cost savings of the merger. The loss of key employees could adversely affect People’s United’s ability to successfully conduct its business, which could have an adverse effect on People’s United’s financial results and the value of its common stock. People’s United may also encounter unexpected difficulties or costs during the integration that could adversely affect its earnings and financial condition, perhaps materially. If People’s United experiences difficulties with the integration process and attendant systems conversion, the anticipated benefits of the merger may not be realized fully or at all or may take longer to realize than expected.

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As with any merger of financial institutions, there also may be business disruptions that cause People’s United and/or United Financial to lose customers or cause customers to remove their accounts from People’s United and/or United Financial and move their business to competing financial institutions. Integration efforts between the two companies may also divert management’s attention and resources. These integration matters could have an adverse effect on each of People’s United and United Financial during this transition period and for an undetermined period after completion of the merger on the combined company. In addition, the actual cost savings of the merger could be less than anticipated or could take longer to anticipate than expected.

The combined company may be unable to retain People’s United and/or United Financial personnel successfully after the merger is completed.

The success of the merger will depend in part on the combined company’s ability to retain the talents and dedication of key employees currently employed by People’s United and United Financial. It is possible that these employees may decide not to remain with People’s United or United Financial, as applicable, while the merger is pending or with the combined company after the merger is consummated. If key employees terminate their employment or if an insufficient number of employees is retained to maintain effective operations, the combined company’s business activities may be adversely affected, and management’s attention may be diverted from successfully integrating United Financial to hiring suitable replacements, all of which may cause the combined company’s business to suffer. In addition, People’s United and United Financial may not be able to locate suitable replacements for any key employees who leave either company or to offer employment to potential replacements on reasonable terms.

The merger agreement limits United Financial’s ability to pursue alternatives to the merger.

The merger agreement contains provisions that make it more difficult for United Financial to sell its business to a party other than People’s United. These provisions include a general prohibition on United Financial’s solicitation of, or, subject to certain exceptions relating to the exercise of fiduciary duties by United Financial’s board of directors, entering into discussions with any third party regarding any acquisition proposal or offer for a competing transaction, the requirement that United Financial pay the $28,278,000 termination fee if the merger agreement is terminated in certain circumstances and the requirement that United Financial submit the merger proposal to a vote of United Financial’s shareholders even if United Financial’s board of directors changes its recommendation in favor of the merger proposal in a manner adverse to People’s United. For more information, see “The Merger Agreement—Agreement Not to Solicit Other Offers,” “The Merger Agreement—Termination Fee” and “The Merger Agreement—Shareholder Meeting of United Financial and Recommendation of United Financial’s Board of Directors” beginning on pages 100, 103 and 99, respectively.

These provisions might discourage a third party that might have an interest in acquiring all or a significant part of United Financial from considering or proposing that acquisition, even if that party were prepared to pay consideration with a higher per share value than the proposed merger consideration. Furthermore, a potential competing acquiror may propose to pay a lower per share price to United Financial’s shareholders than it might otherwise have proposed to pay because of United Financial’s obligation, in connection with termination of the merger agreement under certain circumstances, to pay People’s United the termination fee.

The merger agreement may be terminated in accordance with its terms, and the merger may not be completed.

The merger agreement is subject to a number of conditions, which must be fulfilled in order to complete the merger. Those conditions include: (i) the approval of the merger proposal by the requisite vote of United Financial’s shareholders; (ii) the authorization for listing on NASDAQ of the shares of People’s United common stock to be issued pursuant to the merger; (iii) the receipt of all required regulatory approvals which are necessary to consummate the transactions contemplated by the merger agreement and the expiration of all statutory waiting periods without the imposition of a materially burdensome regulatory condition; (iv) the effectiveness of the registration statement of which this proxy statement/prospectus is a part with respect to the

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People’s United common stock to be issued upon the consummation of the merger; (v) the absence of any order, injunction or other legal restraint preventing the completion of the merger or the bank merger or making the completion of the merger illegal; (vi) subject to certain exceptions and materiality standards provided in the merger agreement, the accuracy of the representations and warranties of each of People’s United and United Financial; (vii) performance in all material respects by each of People’s United and United Financial of its respective obligations under the merger agreement; and (viii) the receipt by each of People’s United and United Financial of an opinion from its respective counsel to the effect that the merger will be treated as a “reorganization” within the meaning of Section 368(a) of the Code. These conditions to the closing of the merger may not be fulfilled in a timely manner or at all, and, accordingly, the merger may not be completed.

In addition, the parties may mutually decide to terminate the agreement at any time, before or after the approval of the merger proposal by United Financial’s shareholders, or the parties may choose to terminate the merger agreement in certain other circumstances. For a more complete discussion of the circumstances under which the merger agreement could be terminated, see “The Merger Agreement—Termination of the Merger Agreement” beginning on page 101.

Lawsuits challenging the merger may be filed against United Financial and People’s United, and an adverse judgment in any such lawsuit or any future similar lawsuits may prevent the merger from becoming effective or from becoming effective within the expected timeframe.

Shareholders of United Financial may file lawsuits against United Financial, People’s United and/or the directors and officers of either company in connection with the merger. One of the conditions to the closing of the merger is that no order, injunction or decree issued by any court or agency of competent jurisdiction or other legal restraint or prohibition that prevents the consummation of the merger or any of the other transactions contemplated by the merger agreement be in effect. If any plaintiff were successful in obtaining an injunction prohibiting United Financial or People’s United defendants from completing the merger on the agreed upon terms, then such injunction may prevent the merger from becoming effective or from becoming effective within the expected timeframe and could result in significant costs to United Financial and/or People’s United, including any cost associated with the indemnification of directors and officers. The defense or settlement of any lawsuit or claim that remains unresolved at the time the merger is completed may adversely affect People’s United’s business, financial condition, results of operations and cash flow.

United Financial’s shareholders will have a reduced ownership and voting interest after the merger and will exercise less influence over management of the combined organization.

United Financial’s shareholders currently have the right to vote in the election of United Financial’s board of directors and on other matters affecting United Financial requiring shareholder approval under Connecticut law and United Financial’s certificate of incorporation and United Financial’s bylaws. Upon the completion of the merger, each of United Financial’s shareholders that receives shares of People’s United common stock will become a People’s United’s shareholder with a percentage ownership of the combined organization that is much smaller than the shareholder’s percentage ownership of United Financial. Based on the number of shares of People’s United common stock and United Financial common stock outstanding on August 30, 2019, the latest practicable date before the filing of this proxy statement/prospectus, and based on the exchange ratio, it is expected that United Financial’s former shareholders as a group will receive shares in the merger constituting approximately 10.1% of the outstanding shares of People’s United common stock immediately after the merger. Because of this, United Financial’s shareholders as a group will have significantly less influence on the management and policies of People’s United than they now have on the management and policies of United Financial.

United Financial’s shareholders will not have dissenters’ or appraisal rights in the merger.

Dissenters’ and appraisal rights are statutory rights that, if applicable under law, enable shareholders to dissent from an extraordinary transaction, such as a merger, and to demand that the corporation pay the fair value for

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their shares as determined by a court in a judicial proceeding instead of receiving the consideration offered to shareholders in connection with the extraordinary transaction. Pursuant to Section 33-856 of the CBCA, shareholders of a Connecticut corporation are not entitled to exercise any appraisal or dissenters’ rights if such corporation’s stock is listed on a national securities exchange. Accordingly, United Financial’s shareholders do not have appraisal or dissenters’ rights with respect to the merger.

Certain of United Financial’s directors and executive officers have interests in the merger that may be different from, or in addition to, the interests of United Financial’s shareholders generally.

In considering the information contained in this proxy statement/prospectus, you should be aware that some of United Financial’s executive officers and directors have interests in the merger that may be different from, or in addition to, the interests of United Financial’s shareholders generally. These interests include the vesting in full of certain outstanding United Financial equity compensation awards, the distribution of certain severance and retirement benefits and rights to continued indemnification and insurance coverage by People’s United from and after the effective time of the merger for acts or omissions occurring at or prior to the effective time of the merger. These interests and arrangements may create potential conflicts of interest. United Financial’s board of directors was aware of these interests and considered these interests, among other matters, in evaluating and negotiating the merger agreement and the merger, and in recommending that United Financial shareholders vote in favor of the merger proposal.

For a more complete discussion of these interests, see “The Merger—Interests of United Financial’s Directors and Executive Officers in the Merger” beginning on page 72.

United Financial’s unaudited prospective financial information is based on various assumptions that may not prove to be correct.

The unaudited prospective financial information set forth in the financial forecasts included under “The Merger—Certain Financial Forecasts of United Financial” beginning on page 70, reflect numerous estimates, assumptions and judgments made by, as well as the information available to, United Financial management at the time they were prepared and United Financial is not aware of whether these estimates, assumptions or judgments they made will prove correct. Such information can be adversely affected by inaccurate assumptions or by known or unknown factors, including the risks and uncertainties described under the sections entitled “Risk Factors” and “Information Regarding Forward-Looking Statements” beginning on pages 23 and 31, respectively, all of which are difficult to predict and many of which are outside the control of United Financial and will be beyond the control of the combined company. Such factors will be important in determining the future results of United Financial, however in view of these uncertainties, the inclusion of certain United Financial unaudited prospective financial information in this proxy statement/prospectus is not and should not be viewed as a representation that the forecasted results will be achieved. See “The Merger—Certain Financial Forecasts of United Financial” beginning on page 70 for more information.

The fairness opinion delivered by United Financial’s financial advisor to United Financial’s board of directors prior to the execution of the merger agreement will not reflect changes in circumstances subsequent to the date of the fairness opinion.

Sandler O’Neill, United Financial’s financial advisor in connection with the merger, delivered its fairness opinion to United Financial’s board of directors on July 15, 2019. The opinion of Sandler O’Neill speaks only as of such date and does not reflect changes that may occur or may have occurred after the date of the opinion, including changes to the operations and prospects of People’s United or United Financial, changes in general market and economic conditions or regulatory or other factors. Any such changes may materially alter or affect the relative values of People’s United and United Financial.

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United Financial and People’s United will be subject to business uncertainties and contractual restrictions while the merger is pending.

Uncertainty about the effect of the merger on employees and customers may have an adverse effect on United Financial or People’s United. These uncertainties may impair United Financial’s or People’s United’s ability to attract, retain and motivate key personnel until the merger is completed and could cause customers and others that deal with United Financial or People’s United to seek to change existing business relationships with United Financial or People’s United. Retention of certain employees by United Financial or People’s United may be challenging while the merger is pending, as certain employees may experience uncertainty about their future roles with the combined company. If key employees depart because of issues relating to the uncertainty and difficulty of integration or a desire not to remain with United Financial or People’s United, United Financial’s business or People’s United’s business could be harmed. In addition, subject to certain exceptions, United Financial has agreed to operate its business in the ordinary course prior to closing, and People’s United is also subject to certain restrictions on the conduct of its business prior to closing. For more information, see “The Merger Agreement—Covenants and Agreements” beginning on page 93.

Failure to complete the merger could negatively impact the stock prices, future businesses and financial results of People’s United and United Financial.

If the merger is not completed, the ongoing businesses of People’s United and United Financial may be adversely affected, and People’s United and United Financial will be subject to several risks, including the following:

In addition, if the merger is not completed, People’s United and/or United Financial may experience negative reactions from the financial markets and from their respective customers and employees. For example, People’s United’s and United Financial’s businesses may be impacted adversely by the failure to pursue other beneficial opportunities due to the focus of management on the merger, without realizing any of the anticipated benefits of completing the merger. The market price of People’s United common stock or United Financial common stock could decline to the extent that the current market prices reflect a market assumption that the merger will be completed. People’s United and/or United Financial also could be subject to litigation related to any failure to complete the merger or to proceedings commenced against People’s United or United Financial to perform their respective obligations under the merger agreement. If the merger is not completed, People’s United and United Financial cannot assure their respective shareholders that the risks described above will not materialize and will not materially affect the business, financial results and stock prices of People’s United and/or United Financial.

If the merger is not completed, People’s United and United Financial will have incurred substantial expenses without realizing the expected benefits of the merger.

Each of People’s United and United Financial has incurred and will incur substantial expenses in connection with the negotiation and completion of the transactions contemplated by the merger agreement, as well as the costs

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and expenses of filing, printing and mailing this proxy statement/prospectus and all filing and other fees paid to the SEC in connection with the merger. If the merger is not completed, People’s United and United Financial would have to recognize these expenses without realizing the expected benefits of the merger.

The shares of People’s United common stock to be received by United Financial’s shareholders as a result of the merger will have different rights from shares of United Financial common stock.

Following completion of the merger, United Financial’s shareholders will become shareholders of People’s United, and their rights as shareholders will be governed by the Delaware General Corporation Law (which we refer to as the “DGCL”) and People’s United’s certificate of incorporation and People’s United’s bylaws. There will be important differences between your current rights as a United Financial shareholder and the rights to which you will be entitled as People’s United’s shareholder. For a discussion of the different rights associated with People’s United common stock and United Financial common stock, see “Comparison of Shareholder Rights” beginning on page 106.

Risks Related to People’s United’s Business

You should read and consider risk factors specific to People’s United’s business that will also affect the combined company after the merger. These risks are described in the sections entitled “Risk Factors” in People’s United’s Annual Report on Form 10-K for the fiscal year ended December 31, 2018 and in other documents incorporated by reference into this proxy statement/prospectus. For more information, see “Where You Can Find More Information” beginning on page 121.

Risks Related to United Financial’s Business

You should read and consider risk factors specific to United Financial’s business that will also affect the combined company after the merger. These risks are described in the sections entitled “Risk Factors” in United Financial’s Annual Report on Form 10-K for the fiscal year ended December 31, 2018 and in other documents incorporated by reference into this proxy statement/prospectus. For more information, see “Where You Can Find More Information” beginning on page 121.

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INFORMATION REGARDING FORWARD-LOOKING STATEMENTS

This proxy statement/prospectus, including information included or incorporated by reference into this proxy statement/prospectus, may contain forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements include, but are not limited to, statements about the benefits of the merger between People’s United and United Financial, including People’s United’s and/or United Financial’s expectations or predictions of future financial or business performance or conditions; statements about People’s United’s and United Financial’s plans, objectives, expectations and intentions with respect to future operations, products and services; and other statements identified by words such as “believe,” “expect,” “anticipate,” “intend,” “target,” “estimate,” “continue,” “positions,” “plan,” “predict,” “project,” “forecast,” “guidance,” “goal,” “objective,” “prospects,” “possible” or “potential,” by future conditional verbs such as “assume,” “will,” “would,” “should,” “could” or “may,” or by variations of such words or by similar expressions. These forward-looking statements are subject to numerous assumptions, risks and uncertainties, which change over time, are difficult to predict and are generally beyond the control of either company. Forward-looking statements speak only as of the date they are made, and People’s United and United Financial assume no duty to update forward-looking statements. Actual results may differ materially from current projections.

In addition to factors previously disclosed in People’s United’s and United Financial’s reports filed with the SEC and those identified elsewhere in this proxy statement/prospectus, the following factors, among others, could cause actual results to differ materially from forward-looking statements or historical performance:

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Additional factors that could cause People’s United’s and United Financial’s results to differ materially from those described in the forward-looking statements can be found in People’s United’s and United Financial’s filings with the SEC as described under “Where You Can Find More Information” beginning on page 121.

You are cautioned not to place undue reliance on forward-looking statements, which speak only as of the date of this proxy statement/prospectus or the date of the applicable document incorporated by reference into this proxy statement/prospectus. All subsequent written and oral forward-looking statements concerning the merger or other matters addressed in this proxy statement/prospectus and attributable to People’s United or United Financial or any person acting on their behalf are expressly qualified in their entirety by the cautionary statements contained or referred to in this section. Except to the extent required by applicable law or regulation, People’s United and United Financial undertake no obligation to update these forward-looking statements to reflect facts, assumptions, events or circumstances that occur after the date on which such forward-looking statement was made.

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THE SPECIAL MEETING OF UNITED FINANCIAL’S SHAREHOLDERS

This section contains information for United Financial’s shareholders about the special meeting that United Financial has called to allow its shareholders to consider and vote on the merger proposal and other matters as described below. On or about September 6, 2019, this proxy statement/prospectus was mailed to holders of United Financial common stock entitled to vote at the special meeting. This proxy statement/prospectus is accompanied by a notice of the special meeting and a form of proxy card that United Financial’s board of directors is soliciting for use at the special meeting and at any adjournments or postponements thereof.

Date, Time and Place of the Special Meeting

The special meeting of shareholders of United Financial will be held at the Connecticut Science Center, 250 Columbus Boulevard, Hartford, Connecticut 06103 on October 22, 2019 at 10:00 a.m., local time.

Purpose of the Special Meeting

At the special meeting, United Financial’s shareholders as of the record date will be asked to consider and vote on the following proposals:

Recommendation of United Financial’s Board of Directors

United Financial’s board of directors has unanimously approved and adopted the merger agreement and the transactions contemplated thereby and recommends that you vote “FOR” the merger proposal, “FOR” the compensation proposal and “FOR” the adjournment proposal.

Record Date, Outstanding Shares, Shares Entitled to Vote and Quorum

United Financial’s board of directors has fixed the close of business on August 27, 2019 as the record date for determining the holders of United Financial common stock entitled to receive notice of and to vote at the special meeting.

As of the record date, there were 50,884,882 shares of United Financial common stock outstanding and entitled to vote at the special meeting. Each shareholder of record on that date is entitled to one vote for each share held on each proposal to be considered at the special meeting.

The presence at the special meeting, in person or by proxy, of a majority of the outstanding shares of United Financial common stock entitled to vote at the special meeting constitutes a quorum for transacting business at the special meeting. All shares of United Financial common stock present in person or represented by proxy, including abstentions, will be treated as present for determining the presence or absence of a quorum for all matters voted on at the special meeting. Broker non-votes will also be counted for purposes of establishing a quorum.

Vote Required, Treatment of Abstentions and Failure to Vote

Merger proposal:

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Compensation proposal:

Adjournment proposal:

United Financial’s shareholders must approve the merger proposal in order for the merger to occur. United Financial’s shareholders are not, however, required to approve the compensation proposal or the adjournment proposal in order for the merger to occur. If United Financial’s shareholders fail to approve the compensation proposal or the adjournment proposal, but approve the merger proposal, the merger may nonetheless occur.

Shares Held by United Financial’s Executive Officers and Directors

As of the record date, the directors and executive officers of United Financial and their affiliates collectively owned, and were entitled to vote, 859,840 shares of United Financial common stock, representing approximately 1.69% of United Financial’s outstanding shares on that date. United Financial currently expects that each of its directors and executive officers and their affiliates will vote their shares of United Financial common stock “FOR” the approval of the merger proposal, although none of them has entered into an agreement requiring them to do so.

When considering the recommendation of United Financial’s board of directors that you vote in favor of the merger proposal, United Financial’s shareholders should be aware that certain of the directors and executive officers of United Financial have certain interests in the merger that may be different from, or in addition to, the interests of United Financial’s shareholders generally. United Financial’s board of directors was aware of these interests and considered them, among other matters, in making its recommendation that United Financial’s shareholders vote to approve the merger proposal. For more information, see “The Merger—Interests of United Financial’s Directors and Executive Officers in the Merger” beginning on page 72.

Voting of Proxies and Incomplete Proxies

A United Financial’s shareholder may vote by proxy or in person at the special meeting. If you hold your shares of United Financial common stock in your name as a shareholder of record, you may authorize the persons

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named in the enclosed proxy card to vote your shares of United Financial common stock at the special meeting in the manner you direct by using one of the following methods:

If you hold shares of United Financial common stock in “street name” through a bank, broker or other nominee, you should check the voting form provided to you by such bank, broker or other nominee to determine whether you may vote through the Internet or by telephone.

All properly signed proxies received prior to the special meeting and not revoked before the vote at the special meeting will be voted at the special meeting according to the instructions indicated on the proxies or, if no instructions are given, the shares of United Financial common stock will be voted “FOR” the agreement and merger proposal, “FOR” the compensation proposal and “FOR” the adjournment proposal; however, for those shares of United Financial common stock held in the United 401(k) Plan, the United 401(k) Plan trustee will, subject to the exercise of its fiduciary responsibilities, vote all unallocated shares of United Financial common stock held in the United 401(k) Plan and allocated shares of United Financial Stock held in the United 401(k) Plan for which no instructions are given, in the same proportion as voting instructions received from other participants in the United 401(k) Plan.

Your vote is very important. Whether or not you plan to attend the special meeting, please take the time to vote by completing, signing, dating and returning the enclosed proxy card to United Financial in the enclosed postage-paid envelope or by submitting a proxy through the Internet or by telephone as described on the enclosed instructions as soon as possible to make sure your shares of United Financial common stock are represented at the special meeting. Submitting a proxy now will NOT prevent you from being able to attend and vote in person at the special meeting.

Shares Held in Street Name and Broker Non-Votes

If your shares of United Financial common stock are held in “street name” through a bank, broker or other nominee, meaning in the name of a bank, broker or other nominee who is the record holder, you must provide such record holder with instructions on how to vote your shares of United Financial common stock. Please follow the voting instructions provided by the bank, broker or other nominee. You may not vote your shares of United Financial common stock held in street name by returning a proxy card directly to United Financial or by voting in person at the special meeting, unless you provide a “legal proxy,” which you must obtain from your bank, broker or other nominee. Further, brokers, banks or other nominees who hold shares of United Financial common stock on behalf of their customers may not give a proxy to United Financial to vote those shares of United Financial common stock with respect to any of the proposals without specific instructions from their customers, as brokers, banks and other nominees do not have discretionary voting power on these matters. Therefore, failure to instruct your bank, broker or other nominee how to vote with respect to the merger proposal will have the same effect as a vote “AGAINST” approval of such proposal. Failure to instruct your bank, broker or other nominee how to vote with respect to the compensation proposal or the adjournment proposal will have no effect on such proposals.

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How to Revoke Your Proxy

If you are a holder of record of United Financial common stock and have previously submitted your proxy, you may revoke your proxy at any time by taking any of the following actions before your proxy is voted at the special meeting:

You should send any written notice of revocation or duly executed new proxy card, as the case may be, to United Financial at the following address:

United Financial Bancorp, Inc.

225 Asylum Street

Hartford, Connecticut 06103

Attn: Marliese L. Shaw, Corporate Secretary

If you hold your shares of United Financial common stock in “street name” through a bank, broker or other nominee, you must contact your record holder to change your vote.

Voting in Person

If you are a shareholder of record of United Financial on August 27, 2019, the record date, you may attend the special meeting and vote in person. Please note, however, that if your shares of United Financial common stock are held of record by a bank, broker or other nominee and you wish to vote at the special meeting, you must obtain a “legal proxy,” executed in your favor from such bank, broker or other nominee who is the holder of record of your shares of United Financial common stock in order to vote your shares of United Financial common stock in person at the special meeting.

If you plan to attend the special meeting, you must hold your shares of United Financial common stock in your own name or have a letter from the record holder of your shares of United Financial common stock confirming your ownership. In addition, you must bring a form of personal photo identification and your admission ticket, which you will have received by mail with this proxy statement/prospectus, with you in order to be admitted to the meeting. United Financial reserves the right to refuse admittance to anyone without proper proof of share ownership, without proper photo identification or without a proper admission ticket. Whether or not you intend to be present at the special meeting, you are urged to complete, sign, date and return the enclosed proxy card to United Financial in the enclosed postage-paid envelope or submit a proxy through the Internet or by telephone as described on the enclosed instructions as soon as possible. This will not prevent you from voting in person at the special meeting, but will assure that your vote is counted if you are unable to attend. If you are then present at the special meeting and wish to vote your shares of United Financial common stock in person, your original proxy may be revoked by voting at the special meeting.

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Participants in the United 401(k) Plan

If you hold shares of United Financial common stock in your plan account under the United 401(k) Plan (including the ESOP), you may direct the voting of the shares held in your United 401(k) Plan account. The United 401(k) Plan trustee will vote your shares in accordance with your instructions. If you do not provide voting instructions to the United 401(k) Plan trustee, the trustee will vote your shares, subject to the exercise of its fiduciary responsibilities, in the same proportion as the instructions received by the trustee from the plan participants. The United 401(k) Plan trustee will not disclose the confidential voting directions of any individual participant to United Financial. If you hold shares of United Financial common stock in the United 401(k) Plan (including the ESOP), you will receive a separate voting instruction explaining the voting process with respect to such shares, including instructions on how to direct the trustee to vote those shares.

Proxy Solicitation

The enclosed proxy is solicited by and on behalf of United Financial’s board of directors. United Financial will pay the expenses of soliciting proxies to be voted at the special meeting, except that United Financial and People’s United have each agreed to share equally the costs of preparing, printing, filing and mailing this document, other than attorneys’ and accountants’ fees, which will be paid by the party incurring the expense. Following the original mailing of the proxies and other soliciting materials, United Financial and its officers and employees may also solicit proxies by mail, telephone, facsimile, electronic mail or in person. No additional compensation will be paid to directors, officers or other employees of United Financial for making these solicitations.

United Financial has retained a proxy solicitation firm, Morrow, to aid it in the solicitation process. United Financial estimates it will pay Morrow a fee of approximately $15,000 plus certain expenses and has agreed to indemnify Morrow against certain losses. United Financial intends to reimburse persons who hold United Financial common stock of record but not beneficially, such as brokers, custodians, nominees and fiduciaries, for their reasonable expenses in forwarding copies of proxies and other soliciting materials to, and requesting authority for the exercise of proxies from, the persons for whom they hold the shares of United Financial common stock.

If you hold shares of United Financial common stock in your plan account under the United 401(k) Plan (including the ESOP), you will have received voting instruction forms that reflect all shares of United Financial common stock for which you may direct the voting under the plan. Under the terms of the United 401(k) Plan, the United 401(k) Plan trustee votes all shares of United Financial common stock held by the United 401(k) Plan, but each United 401(k) Plan participant may provide instructions to the trustee on how to vote the shares of United Financial common stock held in his or her plan account. The United 401(k) Plan trustee will vote your shares of United Financial common stock in accordance with your instructions and, subject to the exercise of its fiduciary responsibilities, will vote all unallocated shares of United Financial common stock held by the United 401(k) Plan and allocated shares of United Financial common stock held by the United 401(k) Plan for which no voting instructions were received in the same proportion as the instructions received from other participants in the United 401(k) Plan. The deadline for returning your voting instructions is 11:59 p.m. on October 17, 2019.

Stock Certificates

If you are a United Financial’s shareholder, you should not send in any certificates representing United Financial common stock at this time. Following the completion of the merger, you will receive separate instructions for the exchange of your certificates representing United Financial common stock for merger consideration. If your shares of United Financial common stock are held in book-entry form, you will not be required to take any additional actions. Promptly following the completion of the merger, shares of United Financial common stock held in book-entry form will automatically be exchanged for the merger consideration.

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Delivery of Proxy Materials to Shareholders Sharing an Address

Only one proxy statement/prospectus is delivered to two or more of United Financial’s shareholders who share an address unless United Financial or its agent has received contrary instructions from one or more of the shareholders. United Financial will deliver promptly upon written or oral request a separate copy of these documents to United Financial’s shareholders at a shared address to which a single copy was delivered. To request that separate copies of these documents be delivered, United Financial’s shareholders can contact United Financial’s proxy solicitor, Morrow by mail at 470 West Avenue, Stamford, CT 06902 or by telephone at (203) 658-9400, for banks and brokers (who may call collect), and all others can call, toll-free, (800) 662-5200. You may also contact United Financial’s proxy solicitor if you received multiple copies of a proxy statement of United Financial and would prefer to receive a single copy in the future.

Assistance

If you need assistance in completing your proxy card, have questions regarding the special meeting or would like additional copies of this proxy statement/prospectus, please contact United Financial Investor Relations at (860) 291-3600 or United Financial’s proxy solicitor, Morrow, at (203) 658-9400, for banks and brokers (who may call collect), and all others can call, toll-free, (800) 662-5200.

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THE PROPOSALS

PROPOSAL NO. 1: THE MERGER PROPOSAL

As discussed elsewhere in this proxy statement/prospectus, the holders of United Financial common stock will consider and vote on the merger proposal. The holders of United Financial common stock should read this proxy statement/prospectus carefully and in its entirety, including the annexes, for more detailed information concerning the merger agreement and the merger. A copy of the merger agreement is attached to this proxy statement/prospectus as Annex A.

Required Vote

Approval of the merger proposal requires the affirmative vote of the holders of at least two-thirds of the shares of United Financial common stock that are outstanding as of the close of business on the record date and entitled to vote on the proposal. If you fail to submit a proxy or vote in person at the special meeting, mark “ABSTAIN” on your proxy or fail to instruct your bank, broker or other nominee with respect to the merger proposal, it will have the same effect as a vote “AGAINST” the proposal.

Vote Recommendation

United Financial’s board of directors unanimously recommends a vote “FOR” the merger proposal. The merger cannot be completed unless United Financial’s shareholders approve the merger proposal. For a more detailed discussion of United Financial’s board of directors’ recommendation, see “The Merger—United Financial’s Reasons for the Merger; Recommendation of United Financial’s Board of Directors” beginning on page 50.

PROPOSAL NO. 2: THE COMPENSATION PROPOSAL

Pursuant to the Dodd-Frank Act and Rule 14a-21(c) under the Securities Exchange Act of 1934, as amended (which we refer to as the “Exchange Act”), United Financial is seeking non-binding, advisory approval from its shareholders of the compensation of United Financial’s named executive officers that is based on or otherwise relates to the merger, as disclosed in “The Merger—Interests of United Financial’s Directors and Executive Officers in the Merger—Quantification of Potential Payments and Benefits to United Financial’s Named Executive Officers in Connection with the Merger” beginning on page 77. The proposal gives United Financial’s shareholders the opportunity to express their views on the merger-related compensation of United Financial’s named executive officers. Accordingly, United Financial is requesting its shareholders to approve the following resolution, on a non-binding, advisory basis:

“RESOLVED, that the compensation that may be paid or become payable to United Financial’s named executive officers in connection with the merger, and the agreements or understandings pursuant to which such compensation may be paid or become payable, in each case as disclosed pursuant to Item 402(t) of Regulation S-K in “The Merger—Interests of United Financial’s Directors and Executive Officers in the Merger—Quantification of Potential Payments and Benefits to United Financial’s Named Executive Officers in Connection with the Merger,” are hereby APPROVED on a non-binding, advisory basis.”

The vote on this proposal is a vote separate and apart from the vote of United Financial shareholders to approve the merger proposal and approval of this proposal is not a condition to completion of the merger. Accordingly, a holder of United Financial common stock may vote to not approve this compensation proposal and vote to approve the merger proposal or vice versa. The vote with respect to this proposal is advisory only and will not be binding on United Financial, regardless of whether the other proposals are approved. If the merger is completed, the merger-related compensation may be paid to United Financial’s named executive officers to the extent payable in accordance with the terms of the compensation agreements and arrangements even if United Financial shareholders fail to approve this compensation proposal.

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Required Vote

Assuming a quorum is present, approval of the compensation proposal requires the affirmative vote of the holders of a majority of the shares of United Financial common stock represented at the special meeting, either in person or by proxy, and entitled to vote on the proposal. If you mark “ABSTAIN” on your proxy with respect to the compensation proposal, it will have the same effect as a vote “AGAINST” the proposal. If you fail to submit a proxy or vote in person at the special meeting or fail to instruct your bank, broker or other nominee how to vote with respect to the compensation proposal, it will have no effect on such proposal.

Vote Recommendation

United Financial’s board of directors unanimously recommends a vote “FOR” the compensation proposal.

PROPOSAL NO. 3: THE ADJOURNMENT PROPOSAL

If, at the special meeting, the number of shares of United Financial common stock present or represented and voting in favor of the merger proposal is insufficient to approve such merger proposal, United Financial may move to adjourn the special meeting in order to enable United Financial’s board of directors to solicit additional proxies in favor of the merger proposal. In this proposal, United Financial is asking its shareholders to authorize the holder of any proxy solicited by United Financial’s board of directors on a discretionary basis to vote in favor of adjourning the special meeting to another time and place for the purpose of soliciting additional proxies, including the solicitation of proxies from United Financial’s shareholders who have previously voted. United Financial does not intend to call a vote on adjournment of the special meeting to solicit additional proxies if the merger proposal is approved at the special meeting. Pursuant to the merger agreement, United Financial is required to adjourn or postpone the special meeting to solicit additional proxies if it has not received proxies representing a sufficient number of votes for the shareholder approvals needed to complete the merger.

Required Vote

Approval of the adjournment proposal requires the affirmative vote of the holders of a majority of the shares of United Financial common stock represented at the special meeting, either in person or by proxy, and entitled to vote on the proposal, regardless of whether a quorum is present. If you mark “ABSTAIN” on your proxy with respect to the adjournment proposal, it will have the same effect as a vote “AGAINST” the proposal. If you fail to submit a proxy or vote in person at the special meeting or fail to instruct your bank, broker or other nominee how to vote with respect to the adjournment proposal, it will have no effect on such proposal.

Vote Recommendation

United Financial’s board of directors unanimously recommends a vote “FOR” the adjournment proposal.

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INFORMATION ABOUT THE COMPANIES

People’s United Financial, Inc.

People’s United is a bank holding company and a financial holding company registered under the BHC Act, and is incorporated under the state laws of Delaware. People’s United is the holding company for People’s United Bank, a national banking association headquartered in Bridgeport, Connecticut.

The principal business of People’s United is to provide, through People’s United Bank and its subsidiaries, commercial banking, retail banking and wealth management services to individual, corporate and municipal customers. Traditional banking activities are conducted primarily within New England and southeastern New York and include extending secured and unsecured commercial and consumer loans, originating mortgage loans secured by residential and commercial properties and accepting consumer, commercial and municipal deposits.

In addition to traditional banking activities, People’s United Bank provides specialized financial services tailored to specific markets including: personal, institutional and employee benefit trust; cash management; and municipal banking. Through its non-banking subsidiaries, People’s United Bank offers: brokerage and life insurance through People’s Securities, Inc.; financial advisory services and investment management services through People’s United Advisors, Inc.; equipment financing through People’s Capital and Leasing Corp. (which we refer to as “PCLC”), People’s United Equipment Finance Corp. (which we refer to as “PUEFC”) and LEAF Commercial Capital, Inc. (which we refer to as “LEAF”); and other insurance services through People’s United Insurance Agency, Inc.

This full range of financial services is delivered through a network of over 400 branches located in Connecticut, southeastern New York, Massachusetts, Vermont, New Hampshire and Maine, including 85 full-service Stop & Shop supermarket branches throughout Connecticut and 62 in southeastern New York that provide customers with seven-day-a-week banking. People’s United Bank’s distribution network includes investment and brokerage offices, commercial banking offices, online banking and investment trading, a 24-hour telephone banking service and participation in a worldwide ATM network. PCLC, PUEFC and LEAF maintain a sales presence in 17 states to support equipment financing operations throughout the United States. People’s United Bank maintains a mortgage warehouse lending group located in Kentucky and a national credits group that has participations in commercial loans and commercial real estate loans to borrowers in various industries on a national scale.

At June 30, 2019, People’s United had total consolidated assets of $51.6 billion, loans of $38.6 billion, deposits of $39.5 billion and stockholders’ equity of $7.0 billion.

The address of People’s United’s principal executive offices is 850 Main Street, Bridgeport, Connecticut 06604, and its telephone number is (203) 338-7171. For additional information about People’s United, see “Where You Can Find More Information” beginning on page 121.

United Financial Bancorp, Inc.

United Financial is a bank holding company and a financial holding company registered under the BHC Act, and is incorporated under the state laws of Connecticut. United Financial is the holding company for United Bank, a Connecticut-chartered stock savings bank headquartered in Hartford, Connecticut.

United Bank is a full service financial services firm offering a complete line of commercial, small business, wealth management and consumer banking products and services to customers throughout Connecticut, Massachusetts and Rhode Island. United Bank maintains 58 branch offices primarily in Connecticut and Massachusetts (including one branch in Rhode Island), as well as commercial loan production offices, mortgage loan production offices, 72 ATMs, telephone banking, mobile banking, and online banking. United Bank’s personal and business banking customers can bank online as well as using mobile and telephone banking channels. United Financial trades on the NASDAQ Global Select Stock Exchange under the ticker symbol “UBNK.”

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At June 30, 2019, United Financial had total assets of $7.34 billion, loans of $7.65 billion, deposits of $5.73 billion and stockholders’ equity of $720.0 million. The address of United Financial’s principal executive offices is 225 Asylum Street, Hartford, Connecticut 06103, and its telephone number is (860) 291-3600. For additional information about United Financial, see “Where You Can Find More Information” beginning on page 121.

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THE MERGER

The following discussion contains material information about the merger. The discussion is subject, and qualified in its entirety by reference, to the merger agreement attached as Annex A to this proxy statement/prospectus. We urge you to read carefully this entire proxy statement/prospectus, including the merger agreement, for a more complete understanding of the merger.

On July 15, 2019, People’s United’s board of directors and United Financial’s board of directors, each approved and adopted the merger agreement and the transactions contemplated thereby. The merger agreement provides for the acquisition by People’s United of United Financial through a merger of United Financial with and into People’s United, with People’s United as the surviving corporation. Immediately following the merger or at such later time as People’s United may determine, United Bank will be merged with and into People’s United Bank, with People’s United Bank as the surviving entity.

Upon completion of the merger, each outstanding share of United Financial common stock held immediately prior to the effective time of the merger, except for shares of United Financial common stock owned by United Financial or People’s United (in each case other than shares of United Financial common stock (1) held in any United Financial benefit plans (other than the United 401(k) Plan, including the ESOP) or trust accounts, managed accounts, mutual funds and the like or otherwise held in a fiduciary or agency capacity, or (2) held, directly or indirectly, in respect of debts previously contracted) (which will be cancelled), will be converted into the right to receive the merger consideration. The value of the merger consideration is dependent upon the value of People’s United common stock at the effective time of the merger and therefore will fluctuate with the market price of People’s United common stock.

For additional and more detailed information regarding the legal documents that govern the merger, including information about the conditions to the merger and the provisions for terminating or amending the merger agreement, see “The Merger Agreement” beginning on page 88.

Background of the Merger

As part of United Financial’s continuous efforts to strengthen its business and increase value for shareholders and other constituencies, United Financial’s board of directors and senior management regularly review and assess United Financial’s business plans and strategic opportunities and challenges, including the possibility of pursuing various strategic transactions. In recent years, these strategic discussions have been set against a backdrop of, among other things, business performance, the impact of low interest rates and the challenging regulatory, compliance and competitive environments facing financial institutions generally, and the impact of the economic environment for United Financial in particular. United Financial’s board of directors and senior management routinely reviewed strategic alternatives including, among others, divesting or acquiring specific lines of business, acquiring, or being acquired by, another financial institution and a number of balance sheet restructuring opportunities. In addition, United Financial’s board of directors and senior management have evaluated the expected current and future earnings impact of the various strategic alternatives in the context of its capital position, risk appetite, asset and deposit acquisition capabilities and multiple interest rate scenarios. From time to time, United Financial’s board of directors and senior management have discussed various strategic alternatives potentially available to United Financial with its financial advisor, Sandler O’Neill, and have discussed potential strategic transaction opportunities with various banking organizations.

On March 21, 2018, United Financial’s board of directors held a regularly scheduled meeting. Representatives of senior management of United Financial were also in attendance. During the meeting, Mr. Crawford discussed corporate strategy, including the impact of the operating environment on United Financial and other banks and the many challenges to continued earnings growth. Mr. Crawford also reported that a recent analyst report had downgraded earnings forecasts for United Financial’s common stock and suggested that the most value to the United Financial common stock would result from a sale of United Financial to another banking organization,

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including People’s United. United Financial’s board of directors discussed United Financial’s earnings potential and considered and discussed the benefits of a potential business combination, including a potential transaction with People’s United.

Following the meeting, Mr. Crawford called Mr. Barnes, and the parties decided to enter into a customary confidentiality agreement in respect of any further discussions regarding a potential business combination. On March 23, 2018, United Financial and People’s United executed a customary confidentiality agreement, and very limited non-public information regarding United Financial was provided to People’s United at that time.

On March 28, 2018, Mr. Crawford, Mr. Barnes and other representatives of senior management of United Financial and People’s United met over dinner where the parties had further discussions about a potential business combination.

On April 18, 2018, United Financial’s senior management discussed strategic alternatives with United Financial’s board of directors at a regularly scheduled meeting. Following a thorough discussion regarding the challenges facing United Financial and the potential benefits of a business combination with People’s United, the board of directors authorized Mr. Crawford to continue exploratory discussions with Mr. Barnes regarding a potential transaction.

Mr. Crawford and Mr. Barnes spoke several times in May 2018 and June 2018 regarding a possible transaction.

On June 7, 2018, representatives of Sandler O’Neill joined a regularly scheduled meeting of United Financial’s board of directors and presented data on potential strategic opportunities and strategic partners that Sandler O’Neill identified based on strategic fit with United Financial and perceived ability to complete a transaction. Following a lengthy discussion with representatives of Sandler O’Neill and United Financial’s senior management, United Financial’s board of directors determined that of the identified strategic partners, only People’s United and a second financial institution (which we refer to as “Company B”) had sufficient perceived interest in a business combination with United Financial and the financial capacity to complete such a transaction, and United Financial’s board of directors authorized representatives of United Financial’s senior management and Sandler O’Neill to pursue discussions regarding potential mergers with each of People’s United and Company B, and to execute a customary confidentiality agreement with Company B.

On July 10, 2018, Mr. Crawford and Mr. Barnes had a dinner meeting during which they continued discussions about a potential business combination and during which Mr. Barnes indicated that People’s United would be interested in pursuing an acquisition of United Financial at an exchange ratio of 1.154 shares of People’s United common stock for each share of United Financial common stock (representing an approximately 19.3% premium based on the share prices of the companies on such date).

On July 12, 2018, United Financial formally engaged Sandler O’Neill to serve as its financial advisor in connection with a potential business combination, based on its extensive financial advisory experience in the banking sector.

Shortly thereafter, representatives of Sandler O’Neill contacted Company B to inquire about its potential interest in a transaction with United Financial, and subsequently United Financial and Company B entered into a customary confidentiality agreement, which contained a customary standstill provision, in respect of any further discussions regarding a potential business combination.

On July 18, 2018, representatives of United Financial’s senior management, its corporate counsel and Sandler O’Neill met with United Financial’s board of directors to discuss a potential transaction with People’s United or Company B. Following a lengthy discussion with representatives of Sandler O’Neill and United Financial’s senior management, United Financial’s board of directors determined that a business combination with either People’s United or Company B had potential to create significant long term value for United Financial’s

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shareholders and authorized representatives of United Financial’s senior management and Sandler O’Neill to continue discussions with People’s United and Company B, and to invite both institutions to participate in due diligence with respect to United Financial. Shortly thereafter, People’s United and Company B were given access to an electronic data room containing non-public information regarding United Financial and began to perform their respective due diligence reviews of United Financial.

Throughout the remainder of July and August 2018, People’s United and Company B conducted extensive due diligence reviews of United Financial.

On August 16, 2018, Mr. Crawford and Mr. Barnes had another meeting where they continued discussions about the terms of a potential business combination and the timing to complete a transaction.

On August 31, 2018, People’s United submitted a non-binding indication of interest in acquiring United Financial in a stock-for-stock merger transaction at a fixed exchange ratio of 1.18 shares of People’s United common stock for each share of United Financial common stock (representing an approximately 22.9% premium based on the share prices of the companies on such date) and on September 4, 2018, Company B also submitted a non-binding indication of interest in acquiring United Financial in a stock-for-stock merger transaction (representing an approximately 24.4% to 29.2% premium based on the share prices of the companies on such date). At special meetings on September 5, 2018 and September 10, 2019, United Financial’s board of directors reviewed both offers thoroughly with representatives of its senior management team, corporate counsel and Sandler O’Neill and, after initially requesting that People’s United increase its proposal, which People’s United did not do, ultimately determined that Company B’s proposal was superior to People’s United’s. United Financial’s board of directors authorized the United Financial management team to pursue Company B’s proposal, after which, on September 10, 2018, United Financial and Company B executed a letter of intent with an exclusivity arrangement with an expiration date of October 15, 2018. On September 11, 2018, Mr. Crawford notified Mr. Barnes that United Financial was rejecting the offer from People’s United and terminated its access to the electronic data room.

After conducting due diligence on one another over the next several weeks, United Financial’s and Company B’s respective management teams decided that a business combination would not generate the pro forma earnings and other financial metrics that they had previously anticipated. Following discussions with United Financial’s board of directors, on October 2, 2018, United Financial terminated discussions with Company B and closed the electronic data room. United Financial’s board of directors decided to continue to assess strategic alternatives, including remaining independent. In the meantime, United Financial’s senior management continued to refine United Financial’s stand-alone three-year operating plan.

Following termination of discussions with Company B, on October 16, 2018, Mr. Crawford contacted Mr. Barnes to notify him of the expiration of United Financial’s exclusive arrangement with Company B. Mr. Barnes noted that People’s United was not interested in continuing further discussions of a potential business combination at that time because it was pursuing another acquisition, but that he would be open to having further discussions about a business combination with United Financial after that transaction closed.

During the fourth quarter of 2018, United Financial’s stock performance experienced a material decline consistent with a broader trend in the market generally, and in the first quarter of 2019, United Financial’s stock price lagged behind its peer group. During this time, United Financial’s board of directors and representatives of its senior management continued to engage in robust discussions regarding United Financial’s expected future performance on a stand-alone basis, including the possibility that United Financial’s common stock price reflected speculation of a potential transaction, as well as in a potential business combination with another financial institution. United Financial’s board of directors also asked senior management to prepare a comparison of United Financial’s earnings and projected stock price potential reflecting a business combination with another financial institution and a stand-alone strategy implementing the company’s three-year operating plan, which

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senior management subsequently delivered to United’s board of directors and discussed at the February 26, 2019 meeting of the board as described below.

Between February 13 and February 15, 2019, Mr. Crawford and Mr. Barnes had discussions at a conference in Florida hosted by Keefe, Bruyette & Woods, Inc., People’s United’s financial advisor (which we refer to as “KBW”). At this conference, a representative of KBW conveyed to Mr. Crawford that People’s United would be interested in acquiring United Financial at an exchange ratio in the range of 1.00 to 1.05 shares of People’s United common stock for each share of United Financial common stock, representing an approximately 12.2% to 17.8% premium based on the share prices of the companies on February 15, 2019.

On February 26, 2019, United Financial’s board of directors held a special meeting to discuss strategic objectives and representatives of United Financial’s senior management presented their comparison of United Financial’s stand-alone strategy versus its projections reflecting a business combination. In an executive session, United Financial’s independent directors discussed a potential business combination, including People’s United’s oral indication of interest in a combination with United Financial, and came to a consensus not to pursue a strategic combination at that time.

From March through May 2019, United Financial’s board of directors met several times to discuss strategic alternatives, including People’s United’s oral indication of interest for a potential combination as well as United Financial’s strategy on a stand-alone basis. On March 12, 2019, United Financial’s board of directors held another special meeting to discuss United Financial’s three-year operating plan and various strategic alternatives. Before making any formal decisions regarding such alternatives, including a potential combination with People’s United, United Financial’s board of directors decided to hire a financial advisor with strategic advisory experience to assist United Financial’s board of directors in evaluating United Financial’s strategic options.

On April 2, 2019, representatives of KBW orally communicated to Mr. Crawford People’s United’s continuing interest in pursuing a business combination.

On April 23, 2019, United Financial retained RP Financial, an independent financial advisor, to evaluate the three-year operating plan that was prepared by United Financial’s senior management at the request of United Financial’s board of directors, as well as to assist United Financial’s board of directors in its assessment of potential alternative strategies that United Financial could feasibly implement to enhance shareholder value on a stand-alone basis. United Financial chose RP Financial because of its strategic planning and board advisory experience, and its expertise in the valuation of financial institutions and financial institution regulation.

On May 10, 2019, United Financial’s board of directors held a special meeting with representatives of its senior management to discuss certain preliminary analyses performed by RP Financial. Representatives of RP Financial presented to United Financial’s board of directors its assessment of United Financial’s three-year operating plan and potential strategic initiatives RP Financial developed with United Financial’s senior management to enhance United Financial’s shareholder value on a stand-alone basis. United Financial’s board of directors and representatives of its senior management discussed the financial performance benefits and execution risks associated with the stand-alone strategies in detail, including that such strategies could not fully address fundamental issues relating to expected trends in the interest rate yield curve and United Financial’s below peer returns.

On May 13, 2019, United Financial’s board of directors held another special meeting with representatives of United Financial’s senior management to discuss strategic alternatives. The discussion included United Financial’s management’s expectations for the future financial performance of United Financial, and feedback from some of its institutional investors suggesting that United Financial should consider a business combination if after performing a stand-alone analysis it was determined that United Financial operating independently could not create the shareholder value they were seeking. Following the discussion, United Financial’s board of directors authorized United Financial’s senior management, with the assistance of Sandler O’Neill, to identify

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financial institutions as potential transaction counterparties based on financial capacity and perceived interest in a business combination with United Financial, and to report back to United Financial’s board of directors.

On or about May 13, 2019, United Financial engaged Sullivan & Cromwell LLP (which we refer to as “Sullivan & Cromwell”) to serve as its legal advisor in connection with a potential strategic transaction.

On May 14, 2019, United Financial’s board of directors held a special meeting with representatives of United Financial’s senior management and Sandler O’Neill. Representatives of Sandler O’Neill reviewed with United Financial’s board of directors Sandler O’Neill’s view of the universe of potential strategic partners for a business combination with United Financial, based on market capitalization, geographical footprint and growth strategy. Representatives of RP Financial and Sullivan & Cromwell were also in attendance at the meeting. Following discussion, United Financial’s board of directors authorized United Financial’s senior management and Sandler O’Neill to solicit preliminary indications of interest regarding a potential business combination from five financial institutions identified by Sandler O’Neill, including People’s United.

Between May 14, 2019 and May 17, 2019, representatives of Sandler O’Neill contacted People’s United and the four other selected financial institutions. Representatives of Sandler O’Neill engaged in preliminary, confidential discussions with each of these institutions to determine whether there was an interest in pursuing a potential business combination with United Financial.

On May 19, 2019, United Financial’s board of directors held a special meeting with representatives of United Financial’s senior management, RP Financial, Sandler O’Neill and Sullivan & Cromwell in attendance. Representatives of Sandler O’Neill reported that People’s United had orally confirmed its potential interest in a transaction with United Financial, and another financial institution expressed potential interest in a transaction but was not prepared to offer an acquisition premium. The other three institutions indicated that they did not have an interest in a transaction with United Financial at that time. Accordingly, United Financial’s board of directors decided to recommence exploratory discussions with People’s United regarding a potential business combination with United Financial and authorized its senior management to pursue such discussions. Shortly after the conclusion of the special meeting, Mr. Crawford contacted Mr. Barnes.

On May 20, 2019, United Financial and People’s United extended the term of their existing confidentiality agreement until May 20, 2021, and the following day, People’s United was provided access to an electronic data room with limited non-public information regarding United Financial.

Following a preliminary due diligence review by People’s United, and based on the results of that review, on May 28, 2019, Mr. Barnes orally communicated to Mr. Crawford an indicative offer to acquire United Financial in a merger at a proposed exchange ratio of 0.91 shares of People’s common stock for each share of United Financial common stock, representing an approximately 8.1% premium over the closing price of the United Financial common stock based on the share prices of the companies on such date.

On May 30, 2019, United Financial’s board of directors held a special meeting to consider People’s United’s proposal. Representatives of United Financial’s senior management, Sandler O’Neill, RP Financial and Sullivan & Cromwell also attended the meeting. Representatives of Sandler O’Neill reported on their initial discussions with KBW regarding the basis for the proposed exchange ratio. United Financial’s board of directors determined it would hold another special meeting to further discuss the proposal from People’s United after Sandler O’Neill received more information from KBW and to review further analyses from RP Financial regarding United Financial’s valuation on a stand-alone basis.

On June 4, 2019, United Financial’s board of directors held a special meeting to further consider People’s United’s proposal and United Financial’s stand-alone strategy. Representatives of United Financial’s senior management, Sullivan & Cromwell, Sandler O’Neill and RP Financial were also in attendance. A representative of Sullivan & Cromwell discussed the fiduciary duties of the board of directors in connection with their

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evaluation of strategic alternatives. Representatives of Sandler O’Neill reported to the board of directors regarding their discussions with KBW regarding the basis for the exchange ratio proposed by People’s United. Representatives of Sandler O’Neill also discussed in detail the recent performance of the banking industry and recent merger transactions in the industry, including general trends of declining premiums in bank merger transactions and required earn-back periods, and reviewed the current proposal from People’s United to acquire United Financial, as compared to recent, similar acquisitions by People’s United. Representatives of RP Financial presented its strategic planning analyses, which updated its previous analyses by, among other things, (i) assuming a complete loss of $41.7 million, as of June 30, 2019, on United Financial’s investment in three limited liability companies intended to generate solar investment tax credits for United Financial (which we refer to as the “D.C. Solar LLCs”), and (ii) developing and analyzing an additional strategic stand-alone scenario. After an extensive discussion of the information provided at the meeting, United Financial’s board of directors took into account a range of considerations, including the limited financial benefits and significant execution risks associated with the stand-alone strategies developed by RP Financial and United Financial’s senior management, and determined that United Financial’s estimated stand-alone valuation was likely to be materially lower than the proposal from People’s United. In light of the discussions, the board of directors authorized United Financial management and Sandler O’Neill to negotiate and execute a customary exclusivity agreement with People’s United.

On June 4 and 5, 2019, Mr. Crawford and representatives of Sandler O’Neill discussed People’s United’s proposal with Mr. Barnes and representatives of KBW and requested an increase in the proposed exchange ratio. On June 5, 2019, People’s United submitted a written non-binding letter of intent to United Financial, reconfirming its proposed exchange ratio of 0.91 shares of People’s United common stock for each share of United Financial common stock, and exclusivity terms set to expire on July 21, 2019. On June 6, 2019, United Financial executed the letter of intent.

On June 7, 2019, Simpson Thacher & Bartlett, counsel to People’s United (which we refer to as “Simpson Thacher”) sent an initial draft of the merger agreement to Sullivan & Cromwell. From June 7, 2019 until the execution of the merger agreement on July 15, 2019, the parties and their respective legal and financial advisors exchanged drafts of, and engaged in discussion and negotiations concerning the terms of, the merger agreement. Extensive documentary and other due diligence continued in parallel with the negotiation of the transaction documentation.

On June 28, 2019, representatives of KBW informed representatives of Sandler O’Neill that in light of the results to date of its due diligence review of United Financial, People’s United would not proceed with a transaction at the previously proposed 0.91 exchange ratio, and conveyed a revised exchange ratio proposal of 0.875 shares of People’s United common stock for each share of United Financial common stock, representing an approximately 4.0% premium over the closing price of the United Financial common stock based on the closing share prices of the companies on the immediately preceding trading date. Representatives of KBW cited concerns about the credit quality of United Financial’s loan portfolio, and further explained to representatives of Sandler O’Neill that, following its due diligence, People’s United had revised its previous assumptions regarding United Financial’s business and increased the amount of non-core loans that People’s United planned to run off during the two years following the consummation of the proposed merger.

On July 2, 2019, United Financial’s board of directors held a special meeting to discuss the 0.875 exchange ratio proposal from People’s United. Representatives of United Financial’s senior management, Sullivan & Cromwell, Sandler O’Neill and RP Financial were also in attendance. Representatives of Sandler O’Neill and Sullivan & Cromwell provided an update on the status of negotiations with People’s United and its financial and legal advisors. Representatives of Sandler O’Neill presented an updated financial analysis of the potential transaction reflecting the revised exchange ratio. After reviewing Sandler O’Neill’s financial analyses and following a thorough discussion, United Financial’s board of directors authorized management to continue to negotiate a business combination with People’s United at the revised exchange ratio.

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On July 3, 2019, representatives of Sandler O’Neill discussed the basis for the revised exchange ratio with representatives of KBW and requested that People’s United increase its proposed exchange ratio, which People’s United declined to do.

On July 9, 2019, members of United Financial’s senior management, together with representatives of Sandler O’Neill and Sullivan & Cromwell, met with representatives of People’s United’s senior management at its headquarters in Bridgeport, Connecticut to perform reverse due diligence on People’s United. During the meeting, representatives of People’s United’s senior management presented on various topics, including strategic outlook, acquisition strategy, capital levels, loan portfolio, relationships with regulators and material litigation, and answered questions from United Financial and its advisors.

On July 11, 2019, United Financial’s board of directors held a special meeting to review the merger agreement and the proposed transaction with People’s United with an exchange ratio of 0.875 shares of People’s United common stock for each share of United Financial common stock. Representatives of United Financial’s senior management, Sullivan & Cromwell, Sandler O’Neill and RP Financial were also in attendance. Mr. Crawford provided an overview of the status of the proposed merger. Representatives of United Financial’s senior management reported to United Financial’s board of directors on People’s United’s presentation to United Financial in Bridgeport, Connecticut. Representatives of Sandler O’Neill reviewed the financial analyses performed by Sandler O’Neill in connection with its evaluation of the consideration to be paid by People’s United in connection with the merger, including discussing the various financial methodologies used in its analysis. Representatives of RP Financial provided an update to its previous analyses that included an analysis of an additional strategic stand-alone scenario under various assumptions that differed from United Financial’s stand-alone strategic plan, as well as comparisons of United Financial’s stand-alone value to the value in connection with the proposed merger with People’s United based on, among other things, its estimates of future earnings per share and tangible book value. See “—RP Financial Analysis” beginning on page 64. A representative of Sullivan & Cromwell reviewed again with United Financial’s board of directors its fiduciary duties in connection with the potential transaction with People’s United and the key terms of the draft merger agreement delivered by Sullivan & Cromwell to Simpson Thacher on July 5, 2019. A representative of Sullivan & Cromwell also reviewed the regulatory requirements for a transaction with People’s United. Representatives of United Financial’s senior management and Sullivan & Cromwell also discussed with United Financial’s board of directors certain considerations in connection with the proposed merger with People’s United that would impact various constituencies, including (i) the long and short-term interests of United Financial, (ii) the long and short-term interests of United Financial’s shareholders, (iii) the interests of United Financial’s employees, customers, creditors and suppliers and (iv) community and societal considerations, including the communities that United Financial serves. Following robust discussion, United Financial’s board of directors authorized United Financial’s senior management to continue negotiations to reach a definitive agreement with People’s United.

Between July 11, 2019 and July 15, 2019, the parties and their respective legal advisors continued to negotiate the terms of the merger agreement.

On July 15, 2019, United Financial’s board of directors held a special meeting to consider the approval of the merger agreement and the transactions contemplated thereby, including the merger with People’s United. Representatives of United Financial’s senior management, Sandler O’Neill, RP Financial and Sullivan & Cromwell were also in attendance. Mr. Crawford updated and reviewed the status of discussions with People’s United with United Financial’s board of directors, noting that the open issues in the merger agreement were resolved. A representative of Sullivan & Cromwell summarized revisions to the merger agreement made subsequent to Sullivan & Cromwell’s prior presentation to United Financial’s board of directors regarding key terms of the proposed transaction. Representatives of Sandler O’Neill reviewed the updated financial analyses performed by Sandler O’Neill in connection with its evaluation of the consideration to be paid by People’s United in connection with the merger, including discussing the various financial methodologies used in its analysis. See “—Opinion of United Financial’s Financial Advisor” beginning on page 53. Representatives of

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Sandler O’Neill then delivered its oral opinion to United Financial’s board of directors, which was subsequently confirmed in writing on the same date, to the effect that, as of such date and based upon and subject to the various factors, assumptions, considerations, qualifications and limitations set forth in its opinion, the exchange ratio set forth in the merger agreement was fair, from a financial point of view, to the holders of United Financial’s common stock. Based on United Financial’s board of directors’ discussions with its financial and legal advisors on July 15, 2019, and after extensive review and discussion, including consideration of the factors described under “—Recommendation of the United Financial Board of Directors and Reasons for the Merger” below, and consideration of the above referenced presentations and those made at the July 11, 2019 special meeting, United Financial’s board of directors unanimously approved and adopted the merger agreement, on the terms reviewed by United Financial’s board of directors, and the transactions contemplated thereby, and declared the merger and other transactions contemplated by the merger agreement to be in the best interests of United Financial and its shareholders. United Financial’s board of directors also directed that the merger agreement and the merger be submitted to United Financial’s shareholders for approval and recommended that United Financial’s shareholders approve and adopt the merger agreement, the proposed merger and any other matters submitted for shareholder approval in connection with the merger agreement and the proposed merger.

Later on July 15, 2019, the merger agreement was executed and delivered by United Financial and People’s United. The parties announced the transaction following the closing of the stock markets in New York on July 15, 2019.

United Financial’s Reasons for the Merger; Recommendation of United Financial’s Board of Directors

In reaching its unanimous decision to approve and adopt the merger agreement, the merger and the other transactions contemplated by the merger agreement, and to recommend that United Financial’s shareholders approve the merger proposal, United Financial’s board of directors evaluated the merger in consultation with United Financial’s senior management, as well as United Financial’s outside financial and legal advisors, and considered a number of factors, including the following factors: