As filed with the Securities and Exchange Commission on January 3, 2019

Registration No. 333-228987

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

Amendment No. 1

to

FORM S-4

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

People’s United Financial, Inc.

(Exact name of registrant as specified in its charter)

850 Main Street

Bridgeport, Connecticut 06604

(203) 338-7171

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

Kristy Berner, Esq.

Executive Vice President, General Counsel and Corporate Secretary

People’s United Financial, Inc.

850 Main Street

Bridgeport, Connecticut 06604

(203) 338-7171

(Name, address, including zip code, and telephone number, including area code, of agent for service)

With copies to:

Approximate date of commencement of proposed sale of the securities to the public: As soon as practicable after this Registration Statement becomes effective and upon completion of the merger described in the enclosed proxy statement/prospectus.

If the securities being registered on this Form are being offered in connection with the formation of a holding company and there is compliance with General Instruction G, check the following box.   ☐

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act of 1933, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.   ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.   ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act. (Check one):

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to section 7(a)(2)(B) of the Securities Act    ☐

If applicable, place an X in the box to designate the appropriate rule provision relied upon in conducting this transaction:

Exchange Act Rule 13e-4(i) (Cross-Border Issuer Tender Offer)    ☐

Exchange Act Rule 14d-1(d) (Cross-Border Third-Party Tender Offer)  ☐

CALCULATION OF REGISTRATION FEE

This registration statement shall hereafter become effective in accordance with the provisions of Section 8(a) of the Securities Act of 1933.

Information contained herein is subject to completion or amendment. A registration statement relating to the shares of People’s United common stock to be issued in the merger has been filed with the Securities and Exchange Commission. These securities may not be sold nor may offers to buy be accepted prior to the time the registration statement becomes effective. This proxy statement/prospectus shall not constitute an offer to sell or the solicitation of an offer to buy nor shall there be any sale of these securities in any jurisdiction in which such offer, solicitation or sale is not permitted or would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction.

PRELIMINARY—SUBJECT TO COMPLETION—DATED JANUARY 3, 2019

MERGER PROPOSED—YOUR VOTE IS VERY IMPORTANT

January [●], 2019

Dear Stockholder:

On November 26, 2018, BSB Bancorp, Inc. (which we refer to as “BSB Bancorp”) 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, BSB Bancorp 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.” Immediately following the merger or at such later time as People’s United may determine, BSB Bancorp’s wholly-owned subsidiary, Belmont Savings 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 BSB Bancorp common stock, par value $0.01 per share (which we refer to as “BSB Bancorp common stock”), held immediately prior to the effective time of the merger, except for specified shares of BSB Bancorp common stock owned by BSB Bancorp or People’s United (which will be cancelled), will be converted into the right to receive 2.0 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.

Shares of People’s United common stock are listed on the NASDAQ Global Select Market under the symbol “PBCT.” Shares of BSB Bancorp common stock are listed on the NASDAQ Capital Market (which we refer to, together with the NASDAQ Global Select Market, as “NASDAQ”) under the symbol “BLMT.” Based on the closing price of People’s United common stock on NASDAQ on November 26, 2018, the last trading day before public announcement of the merger, the value of the per share merger consideration payable to holders of BSB Bancorp common stock would be $32.42. Based on the closing price of People’s United common stock on NASDAQ on December 31, 2018, the last practicable trading date before the date of the attached proxy statement/prospectus, the value of the per share merger consideration payable to holders of BSB Bancorp common stock would be $28.86. You should obtain current market quotations for both People’s United common stock and BSB Bancorp common stock. Based on the number of shares of BSB Bancorp common stock outstanding and the number of shares of BSB Bancorp common stock issuable pursuant to outstanding BSB Bancorp stock options and other BSB Bancorp equity awards, in each case as of December 31, 2018, the total number of shares of People’s United common stock expected to be issued in connection with the merger is approximately 20,535,504. In addition, based on the number of issued and outstanding shares of People’s United common stock and BSB Bancorp common stock on December 31, 2018, and based on the exchange ratio of 2.0, holders of shares of BSB Bancorp common stock as of immediately prior to the closing of the merger will hold, in the aggregate, approximately 5.16% of the issued and outstanding shares of People’s United common stock immediately following the closing of the merger (without giving effect to any People’s United common stock held by BSB Bancorp’s stockholders prior to the merger).

BSB Bancorp will hold a special meeting of its stockholders (which we refer to as the “special meeting”) in connection with the merger. BSB Bancorp’s stockholders will be asked to vote to approve the merger, as described in the attached proxy statement/prospectus. The merger cannot be completed unless, among other things, the holders of a majority of the outstanding shares of BSB Bancorp common stock vote to approve the merger. At the special meeting, BSB Bancorp’s stockholders will also be asked to vote on (i) the non-binding, advisory proposal to approve the compensation that certain named executive officers of BSB Bancorp may receive that is based on or otherwise relates to the merger and (ii) a proposal to approve the adjournment of the special meeting, if necessary or appropriate, to solicit additional proxies in favor of the merger proposal. The special meeting of stockholders of BSB Bancorp will be held in the Cambridge Room at the Westin Waltham, 70 Third Avenue, Waltham, Massachusetts 02451 on February 27, 2019 at 10:00 a.m., local time. BSB Bancorp’s board of directors has unanimously approved and adopted the merger agreement and the transactions contemplated thereby and recommends that you vote “FOR” the approval of the merger, and “FOR” the other matters to be considered at the special meeting.

The attached proxy statement/prospectus, which serves as the proxy statement for the special meeting of the stockholders of BSB Bancorp 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 27. You can also obtain information about BSB Bancorp 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.

Your vote is very important. To ensure your representation at the special meeting, please promptly complete sign, date and return the enclosed proxy card to BSB Bancorp in the enclosed postage-paid envelope or by submitting a proxy through the Internet or by telephone as described on the enclosed instructions. If you hold your shares in “street name,” you should instruct your broker, bank or other nominee how to vote in accordance with the voting instruction form you receive from your broker, bank or other nominee.

Sincerely,

Robert M. Mahoney

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 January [●], 2019, and is first being mailed to BSB Bancorp’s stockholders on or about January [●], 2019.

ADDITIONAL INFORMATION

The accompanying proxy statement/prospectus incorporates by reference important business and financial information about People’s United Financial, Inc. (which we refer to as “People’s United”) and BSB Bancorp, Inc. (which we refer to as “BSB Bancorp”) 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 BSB Bancorp 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 BSB Bancorp at www.belmontsavings.com (“Investor Relations” tab under the heading “SEC Filings” and subheading “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, you must request them no later than five business days before the date of the special meeting. This means that BSB Bancorp’s stockholders requesting documents must do so by February 20, 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 107 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 BSB Bancorp common stock, please contact BSB Bancorp’s proxy solicitor at the address or telephone number listed below:

Laurel Hill Advisory Group, LLC

2 Robbins Lane, Suite 201

Jericho, New York 11753

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 January [●], 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.

NOTICE OF SPECIAL MEETING OF STOCKHOLDERS

January [●], 2019

To the stockholders of BSB Bancorp, Inc.:

Notice is hereby given that a special meeting of stockholders (which we refer to as the “special meeting”) of BSB Bancorp, Inc., a Maryland corporation (which we refer to as “BSB Bancorp”), will be held in the Cambridge Room at the Westin Waltham, 70 Third Avenue, Waltham, Massachusetts 02451 on February 27, 2019 at 10:00 a.m., local time, for the purpose of considering and voting upon the following matters:

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

BSB Bancorp’s board of directors has fixed the close of business on December 31, 2018 as the record date for determination of stockholders entitled to notice of and to vote at the special meeting, and only stockholders of record on said date will be entitled to receive notice of and to vote at said meeting.

The affirmative vote of the holders of a majority of the outstanding shares of BSB Bancorp 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 votes cast at the special meeting is required to approve the compensation proposal and a majority of the votes present in person or by proxy is required to approve the adjournment proposal.

BSB Bancorp’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 BSB Bancorp 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 BSB Bancorp 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 BSB Bancorp 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.

By Order of the Board of Directors,

John A. Citrano

Corporate Secretary

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 stockholder. 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 of BSB Bancorp’s stockholders 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 BSB Bancorp common stock, par value $0.01 per share (which we refer to as “BSB Bancorp 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.

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Compensation proposal:

Adjournment proposal:

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

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 February 26, 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 BSB Bancorp 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 are a participant in the Belmont Savings Bank Employee Stock Ownership Plan (which we refer to as the “ESOP”), you will have received voting instruction forms that reflect all shares of BSB Bancorp common stock for which you may direct the voting under the plan. Under the terms of the ESOP, the ESOP trustee votes all shares of BSB Bancorp common stock held by the ESOP, but each ESOP participant may provide instructions to the trustee on how to vote the shares of BSB Bancorp common stock allocated to his or her plan account. The ESOP trustee will vote your shares of BSB Bancorp common stock in accordance with your instructions and, subject to the exercise of its fiduciary responsibilities, will vote all unallocated shares and allocated shares of BSB Bancorp common stock held by the ESOP for which no voting instructions were received in the same proportion as the instructions received from participants. The deadline for returning your voting instructions is 5:00 p.m. Eastern Time on February 20, 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 BSB Bancorp at the following address:

BSB Bancorp, Inc.

2 Leonard Street

Belmont, Massachusetts 02478

Attn: John A. Citrano, Corporate Secretary

If you hold your shares of BSB Bancorp 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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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 34, 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 107.

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, BSB Bancorp’s stockholders cannot be certain of the market value of the merger consideration they will receive.

Upon completion of the merger, each outstanding share of BSB Bancorp common stock held immediately prior to the effective time of the merger, except for specified shares of BSB Bancorp common stock owned by BSB Bancorp or People’s United (which will be cancelled), will be converted into the right to receive 2.0 shares of People’s United common stock. 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 BSB Bancorp common stock. The market value of People’s United common stock and BSB Bancorp 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 BSB Bancorp’s stockholders and on the date of the BSB Bancorp 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 BSB Bancorp common stock.

The market price of People’s United common stock and BSB Bancorp 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 BSB Bancorp’s operations or business prospects, including market sentiment regarding People’s United’s and/or BSB Bancorp’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 BSB Bancorp. Accordingly, at the time of the BSB Bancorp special meeting, BSB Bancorp’s stockholders will not necessarily know or be able to 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 BSB Bancorp common stock.

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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 BSB Bancorp currently.

The businesses of People’s United and BSB Bancorp 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 BSB Bancorp. For a discussion of the businesses of People’s United and BSB Bancorp 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 107.

The success of the merger and integration of People’s United and BSB Bancorp 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 page 70. 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. 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 Massachusetts DOB

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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 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 BSB Bancorp 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 BSB Bancorp 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 BSB Bancorp and its subsidiaries, taken as a whole). See “The Merger—Regulatory Approvals Required for the Merger,” beginning on page 70.

Combining People’s United and BSB Bancorp 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 BSB Bancorp 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 BSB Bancorp 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. As with any merger of financial institutions, there also may be business disruptions that cause People’s United and/or BSB Bancorp to lose customers or cause customers to remove their accounts from People’s United and/or BSB Bancorp 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 BSB Bancorp during this transition period and for an

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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 BSB Bancorp 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 BSB Bancorp. It is possible that these employees may decide not to remain with People’s United or BSB Bancorp, 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 BSB Bancorp to hiring suitable replacements, all of which may cause the combined company’s business to suffer. In addition, People’s United and BSB Bancorp 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 BSB Bancorp’s ability to pursue alternatives to the merger.

The merger agreement contains provisions that make it more difficult for BSB Bancorp to sell its business to a party other than People’s United. These provisions include a general prohibition on BSB Bancorp’s solicitation of, or, subject to certain exceptions relating to the exercise of fiduciary duties by BSB Bancorp’s board of directors, entering into discussions with any third party regarding any acquisition proposal or offer for a competing transaction, the requirement that BSB Bancorp pay the $12.5 million termination fee if the merger agreement is terminated in certain circumstances and the requirement that BSB Bancorp submit the merger proposal to a vote of BSB Bancorp’s stockholders even if BSB Bancorp’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—Stockholder Meeting of BSB Bancorp and Recommendation of BSB Bancorp’s Board of Directors,” beginning on pages 86, 88 and 85, respectively.

These provisions might discourage a third party that might have an interest in acquiring all or a significant part of BSB Bancorp 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 BSB Bancorp’s stockholders than it might otherwise have proposed to pay because of BSB Bancorp’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 BSB Bancorp’s stockholders; (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 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 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 BSB Bancorp; (vii) performance in all material respects by each of People’s United and BSB Bancorp of its respective obligations under the merger agreement;

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and (viii) the receipt by each of People’s United and BSB Bancorp 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 the BSB Bancorp stockholders, or People’s United or BSB Bancorp 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 87.

Lawsuits challenging the merger may be filed against BSB Bancorp 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.

Stockholders of BSB Bancorp may file lawsuits against BSB Bancorp, 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 BSB Bancorp 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 BSB Bancorp 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.

BSB Bancorp’s stockholders will have a reduced ownership and voting interest after the merger and will exercise less influence over management of the combined organization.

BSB Bancorp’s stockholders currently have the right to vote in the election of BSB Bancorp’s board of directors and on other matters affecting BSB Bancorp requiring stockholder approval under Maryland law and BSB Bancorp’s articles of incorporation and bylaws. Upon the completion of the merger, each of BSB Bancorp’s stockholders that receives shares of People’s United common stock will become a stockholder of People’s United with a percentage ownership of the combined organization that is much smaller than the stockholder’s percentage ownership of BSB Bancorp. Based on the number of shares issued and outstanding on December 31, 2018, the latest practicable date before the filing of this proxy statement/prospectus, and based on the exchange ratio of 2.0, it is expected that BSB Bancorp’s former stockholders as a group will receive shares in the merger constituting approximately 5.16% of the outstanding shares of People’s United common stock immediately after the merger. Because of this, BSB Bancorp’s stockholders 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 BSB Bancorp.

BSB Bancorp’s stockholders will not have dissenters’ or appraisal rights in the merger.

Dissenters’ and appraisal rights are statutory rights that, if applicable under law, enable stockholders to dissent from an extraordinary transaction, such as a merger, and to demand that the corporation pay the fair value for their shares as determined by a court in a judicial proceeding instead of receiving the consideration offered to stockholders in connection with the extraordinary transaction. Stockholders of a Maryland corporation are not entitled to exercise any rights of an objecting stockholder under the MGCL if the corporation’s stock is listed on a national securities exchange. BSB Bancorp’s stock is listed on NASDAQ. Furthermore, under BSB Bancorp’s articles of incorporation, BSB Bancorp’s stockholders are not entitled to exercise any rights of an objecting stockholder provided under the MGCL, unless BSB Bancorp’s board of directors determines that such rights apply with respect to a transaction. The board of directors has not made such a determination with respect to the

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merger. Accordingly, the BSB Bancorp stockholders will not be entitled to assert any appraisal or dissenters’ rights with respect to their shares of BSB Bancorp common stock in connection with the merger.

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

In considering the information contained in this proxy statement/prospectus, you should be aware that some of BSB Bancorp’s executive officers and directors have interests in the merger that may be different from, or in addition to, the interests of BSB Bancorp’s stockholders generally. These interests include the vesting in full of certain outstanding BSB Bancorp equity compensation awards and rights to continued indemnification and insurance coverage by People’s United after the merger for acts or omissions occurring before the merger. These interests and arrangements may create potential conflicts of interest. BSB Bancorp’s board of directors was aware of these interests and considered these interests, among other matters, when making its decision to approve the merger and in recommending that BSB Bancorp’s stockholders vote in favor of the merger proposal.

For a more complete discussion of these interests, see “The Merger—Interests of BSB Bancorp’s Directors and Executive Officers in the Merger,” beginning on page 60.

The fairness opinion delivered by BSB Bancorp’s financial advisor to BSB Bancorp’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.

J.P. Morgan, BSB Bancorp’s financial advisor in connection with the merger, delivered its fairness opinion to BSB Bancorp’s board of directors on November 26, 2018. The opinion of J.P. Morgan 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 BSB Bancorp, 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 BSB Bancorp.

BSB Bancorp 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 BSB Bancorp or People’s United. These uncertainties may impair BSB Bancorp’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 BSB Bancorp or People’s United to seek to change existing business relationships with BSB Bancorp or People’s United. Retention of certain employees by BSB Bancorp 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 BSB Bancorp or People’s United, BSB Bancorp’s business or People’s United’s business could be harmed. In addition, subject to certain exceptions, BSB Bancorp 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 79.

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

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

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In addition, if the merger is not completed, People’s United and/or BSB Bancorp may experience negative reactions from the financial markets and from their respective customers and employees. For example, People’s United’s and BSB Bancorp’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’s or BSB Bancorp’s 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 BSB Bancorp also could be subject to litigation related to any failure to complete the merger or to proceedings commenced against People’s United or BSB Bancorp to perform their respective obligations under the merger agreement. If the merger is not completed, People’s United and BSB Bancorp cannot assure their respective stockholders 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 BSB Bancorp.

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

Each of People’s United and BSB Bancorp 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 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 BSB Bancorp 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 BSB Bancorp’s stockholders as a result of the merger will have different rights from shares of BSB Bancorp common stock.

Following completion of the merger, BSB Bancorp’s stockholders will become stockholders of People’s United, and their rights as stockholders 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 bylaws. There will be important differences between your current rights as a stockholder of BSB Bancorp and the rights to which you will be entitled as a stockholder of People’s United. For a discussion of the different rights associated with People’s United common stock and BSB Bancorp common stock, see “Comparison of Stockholder Rights,” beginning on page 92.

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, 2017 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 107.

Risks Related to BSB Bancorp’s Business

You should read and consider risk factors specific to BSB Bancorp’s business that will also affect the combined company after the merger. These risks are described in the sections entitled “Risk Factors” in BSB Bancorp’s Annual Report on Form 10-K for the fiscal year ended December 31, 2017 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 107.

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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 BSB Bancorp, including People’s United’s and/or BSB Bancorp’s expectations or predictions of future financial or business performance or conditions; statements about People’s United’s and BSB Bancorp’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 BSB Bancorp 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 BSB Bancorp’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 BSB Bancorp’s results to differ materially from those described in the forward-looking statements can be found in People’s United’s and BSB Bancorp’s filings with the SEC, including People’s United’s Annual Report on Form 10-K for the fiscal year ended December 31, 2017 and BSB Bancorp’s Annual Report on Form 10-K for the fiscal year ended December 31, 2017.

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 BSB Bancorp 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 BSB Bancorp 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 BSB BANCORP’S STOCKHOLDERS

This section contains information for BSB Bancorp’s stockholders about the special meeting that BSB Bancorp has called to allow its stockholders to consider and vote on the merger proposal and other matters as described below. On or about January [●], 2019, this proxy statement/prospectus was mailed to holders of BSB Bancorp common stock entitled to vote at the special meeting. This proxy statement/prospectus is accompanied by a notice of the special meeting of BSB Bancorp’s stockholders and a form of proxy card that BSB Bancorp’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 stockholders of BSB Bancorp will be held in the Cambridge Room at the Westin Waltham, 70 Third Avenue, Waltham, Massachusetts 02451 on February 27, 2019 at 10:00 a.m., local time.

Purpose of the Special Meeting

At the special meeting, BSB Bancorp’s stockholders as of the record date will be asked to consider and vote on the following proposals:

Recommendation of BSB Bancorp’s Board of Directors

BSB Bancorp’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

BSB Bancorp’s board of directors has fixed the close of business on December 31, 2018 as the record date for determining the holders of BSB Bancorp common stock entitled to receive notice of and to vote at the special meeting.

As of the record date, there were 9,776,429 shares of BSB Bancorp common stock outstanding and entitled to vote at the special meeting, held by 266 holders of record. Each stockholder 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 (in person or by proxy) of holders of a majority of the shares entitled to vote at the special meeting constitutes a quorum for transacting business at the special meeting. All shares of BSB Bancorp common stock present in person or represented by proxy, including abstentions and broker non-votes, will be treated as present and entitled to vote for purposes of determining the presence or absence of a quorum for all matters voted on at the special meeting.

Vote Required, Treatment of Abstentions and Failure to Vote

Merger proposal: