As filed with the Securities and Exchange Commission on August 29, 2017December 23, 2021

Registration No. 333-                

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORMS-4

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

OCEANFIRST FINANCIAL CORP.

(Exact name of registrant as specified in its charter)

975 HOOPER AVENUE, TOMS RIVER, NEW JERSEY 08753110 WEST FRONT STREET, RED BANK, NEW JERSEY 07701

(732)240-4500

(Address, Including Zip Code, and Telephone Number, Including Area Code, of Registrant’s Principal Executive Offices)

Christopher D. Maher

President and Chief Executive Officer

975 Hooper Avenue110 West Front Street

Toms River,Red Bank, New Jersey 0875307701

(732)240-4500

(Address, Including Zip Code, and Telephone Number, Including Area Code, of Agent for Service)

Copies to:

Approximate date of commencement of proposed sale to the public: As soon as practicable after this Registration Statement becomes effective and the conditions to the closing of the mergermergers described herein have been satisfied or waived.

If the securities being registered on this Form are to be 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 of 1933, check the following box and list the Securities Act of 1933 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, anon-accelerated filer, or a smaller reporting company or emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer” andfiler,” “smaller reporting company” and “emerging growth company” in Rule12b-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 Rule13e-4(i) (Cross-Border Issuer Tender Offer)  ☐

Exchange Act Rule14d-14d-1(d) 1(d) (Cross-Border Third-Party Tender Offer)  ☐

CALCULATION OF REGISTRATION FEE

The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933, as amended, or until the Registration Statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a), may determine.

Information contained herein is subject to completion or amendment. A registration statement relating to these securities 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 document doesshall not constitute an offer to sell or athe solicitation of anany offer to buy nor shall there be any sale of these securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or from any person to whom it is unlawful to makequalification under the securities laws of any such offer or solicitation in such jurisdiction.

PRELIMINARY — SUBJECT TO COMPLETION — DATED AUGUST 29, 2017DECEMBER 23, 2021

Prospectus		Proxy Statement
		Prospectus

MERGER AND SHARE ISSUANCE PROPOSED — YOUR VOTE IS VERY IMPORTANT

Dear Stockholder:Partners Stockholders:

On June 30, 2017,November 4, 2021, OceanFirst Financial Corp., a Delaware corporation (which we refer to as “OceanFirst”), Sun Bancorp, Inc., a New Jersey corporationthe parent company of OceanFirst Bank, National Association (which we refer to as “Sun”), and Mercury Merger Sub Corp., a New Jersey corporation and a wholly-owned subsidiary of OceanFirst (which we refer to as “Merger Sub”“OceanFirst Bank”), entered into an Agreement and Plan of Merger (which we refer to as the “merger agreement”) that provides for the combinationwith Partners Bancorp, a Maryland corporation (which we refer to as “Partners”), and Coastal Merger Sub Corp., a Maryland corporation and wholly-owned subsidiary of OceanFirst and Sun. Under(which we refer to as “merger sub”). Pursuant to the terms ofand subject to the conditions set forth in the merger agreement, (i) Merger Submerger sub will merge with and into SunPartners (which we refer to as the “first-step merger”), with Sun continuingPartners as the surviving corporation in the first-step merger and as a wholly-owned subsidiary of OceanFirst, (ii)and immediately following the completioneffective time of the first-step merger, SunPartners will merge with and into OceanFirst, with OceanFirst as the surviving corporation (which, together with the first-step merger, we refer to as the “integrated mergers”). Immediately following the consummation of the integrated mergers, The Bank of Delmarva, a Delaware chartered member bank (which we refer to as the “second-step merger” and, together with the first-step merger, the “integrated mergers”), with OceanFirst continuing as the surviving corporation in the second-step merger (we refer to the surviving corporation following the second-step merger as the “combined company”), and (iii) immediately following the completion of the integrated mergers, Sun National Bank, a national bank and a wholly-owned subsidiary of Sun (which we refer to as “Sun National“Delmarva Bank”), will merge with and into OceanFirst Bank, a wholly-owned subsidiary of OceanFirst (which we refer to as “OceanFirst Bank”), with OceanFirst Bank beingas the surviving bank in such merger (which we refer to as the “Delmarva Bank merger”), and immediately following the effective time of the Delmarva Bank merger, Virginia Partners Bank, a Virginia chartered member bank (which we refer to as “Virginia Partners Bank”), will merge with and into OceanFirst Bank, with OceanFirst Bank as the surviving bank (which, together with the Delmarva Bank merger, we refer to as the “bank merger”mergers” and the bank mergers, together with the integrated mergers, which we refer to as the “Transactions”“mergers”).

At the effective time of the first-step merger, each share of Partners common stock, par value $0.01 per share (which we refer to as “Partners common stock”), that is issued and outstanding immediately prior to the effective time of the first-step merger, except for shares of Partners common stock owned by Partners as treasury shares, or by OceanFirst or any subsidiary of Partners or OceanFirst (other than any such shares held in employee benefit plans or related trust account, managed accounts, mutual funds, or otherwise held in a fiduciary capacity or as a result of debt previously contracted) (which we refer to as the “effective time”“exception shares”), each outstanding share of the common stock, par value $5.00 per share, of Sun (which we refer to as “Sun common stock”), except for certain shares of Sun common stock owned by Sun or OceanFirst, will be converted into the right to receive either:

Holders of Sun common stock, will havepar value $0.01 per share, of OceanFirst (which we refer to as “OceanFirst common stock”) or (b) $10.00 in cash (which we refer to as the right to elect to receive the cash consideration or“cash consideration” and together with the stock consideration, we refer to as the “merger consideration”), in each case, at the election of the holder of Partners common stock, subject to (x) a maximum of forty percent (40%) of the shares of Partners common stock being convertible into cash and (y) the allocation and proration provisions of the merger agreement. TheNo fractional shares, if any, of OceanFirst common stock will be issued in connection with the first-step merger, agreement providesand any holder of Partners common stock that would be entitled to fractional shares of OceanFirst common stock shall receive cash in lieu of such fractional shares.

Although the aggregate amountexchange ratio in respect of the stock consideration and the cash consideration will not exceedare fixed, the product of (x) $3.78 and (y) the total number of shares of Sun common stock issued and outstanding immediately prior to the effective time.

The market value of the stock consideration (and, therefore, the aggregate value of the merger consideration) will fluctuate with the market price of OceanFirst common stock and will not be known at the time that holdersPartners stockholders vote on the first-step merger. Based on the $23.21 closing price of SunOceanFirst common stock on the NASDAQ Global Select Market (which we refer to as the “Sun shareholders”“Nasdaq”) vote on November 3, 2021, the first-step merger.last full trading day before the public announcement of the mergers, the value of stock consideration was equal to $10.47. Based on the $[●] closing price of OceanFirst common stock on the NASDAQNasdaq on [●], 2017,2022 the latest practicable trading day before the printing of this jointthe accompanying proxy statement/prospectus, the per share value of the mergerstock consideration was equal to $[●] (and the aggregate value of the merger consideration was equal to approximately $[●] million), which includes the value of the stock portion of the merger consideration and the cash portion of the merger consideration.. Based on the 0.7884 exchange ratio and the number of shares of SunPartners common stock outstanding as of [●], 2017 (which includes the number of shares of Sun common stock underlying Sun’s restricted stock awards and restricted stock award units as of [●], 2017),

the maximum number of shares of OceanFirst common stock estimated to be issuable at the effective time is [●].We urge you to obtain current market quotations for OceanFirst (trading symbol “OCFC”) and SunPartners (trading symbol “SNBC”“PTRS”)..

OceanFirstPartners will hold a special meeting of its stockholders (which we refer to as the “OceanFirst special meeting”) in connection with the issuance of the shares of OceanFirst common stock representing the stock consideration (which we refer to as the “OceanFirst share issuance”).mergers. At the OceanFirstPartners special meeting, the holders of OceanFirst common stock (which we refer to as the “OceanFirst stockholders”) will be asked to vote to approve the OceanFirst share issuance. Approval of the OceanFirst share issuance requires the affirmative vote of a majority of the total votes cast by the OceanFirstPartners stockholders at the OceanFirst special meeting.

Sun will hold a special meeting of its shareholders (which we refer to as the “Sun special meeting”) in connection with the first-step merger. At the Sun special meeting, Sun shareholders will be asked to vote to approve the merger agreement, and the transactions contemplated thereby, and related matters as described in this jointthe accompanying proxy statement/prospectus. Under New JerseyMaryland law, and Sun’s organizational documents, approval of the merger agreement requires the affirmative vote of a majorityat least two-thirds of all of the votes entitled to be cast at the special meeting by Sun shareholdersthe holders of shares of Partners common stock entitled to vote at the Sun special meeting.

The OceanFirst special meeting will be completely virtual and held online via live webcast at [●] Eastern Time, on [●], 2017 at 975 Hooper Avenue, Toms River, New Jersey 08753, at [●] local time. The Sun special2022. No physical meeting will be held on [●], 2017 at 350 Fellowship Road, Suite 101, Mt. Laurel, New Jersey 08054, at [●] local time.held.

The Sun board of directors of Partners unanimously recommends that Sun shareholdersPartners stockholders vote “FOR” the approval of the merger agreement and the transactions contemplated thereby, including the first-step merger, “FOR” the Sun merger-related compensation proposal and “FOR” the Sun adjournment proposal.other proposals to be considered at the special meeting.

The OceanFirst board of directors unanimously recommends that OceanFirst stockholders vote “FOR” the OceanFirst share issuance and “FOR” the OceanFirst adjournment proposal.

This jointaccompanying proxy statement/prospectus describes the Sun special meeting, the OceanFirst special meeting, the Transactions, the OceanFirst share issuance,mergers, the documents related to the Transactionsmergers and other related matters.Please carefully read thisthe entire jointaccompanying proxy statement/prospectus, including “Risk“Risk Factors,” beginning on page[●], for a discussion of the risks relating to the proposed merger and the OceanFirst share issuancemergers. . You also can obtain information about OceanFirst and Sun from documents that eachit has filed with the Securities and Exchange Commission.

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

The securities to be issued in the first-step merger are not savings or deposit accounts or other obligations of any bank ornon-bank subsidiary of either OceanFirst or Sun,Partners, and they are not insured by the Federal Deposit Insurance Corporation or any other governmental agencyagency..

The date of this jointthe accompanying proxy statement/prospectus is [●], 2017,2022 and it is first being mailed or otherwise delivered to OceanFirstPartners stockholders and Sun shareholders on or about [●], 2017.2022.

NOTICE OF SPECIAL MEETING OF STOCKHOLDERS

To the Stockholders of OceanFirst:Partners Stockholders:

OceanFirst will hold the OceanFirstA virtual special meeting of the stockholders of Partners Bancorp, or Partners, is scheduled to be held online via live webcast at [●] local time,Eastern Time, on [●], 2017, at 975 Hooper Avenue, Toms River, New Jersey 087532022 to consider and vote upon the following matters:proposals:

We have fixed the close of business on [●], 2017,2022 as the record date for the OceanFirst special meeting (which we refer to as the “OceanFirst record date”).meeting. Only OceanFirstPartners stockholders of record as of the OceanFirstthis record date are entitled to notice of, and to vote at, the OceanFirst special meeting, or any adjournment of the OceanFirst special meeting. ApprovalUnder Maryland law, approval of the OceanFirst share issuancemerger proposal requires the affirmative vote of at least two-thirds of the votes entitled to be cast at the special meeting by the holders of shares of Partners common stock entitled to vote at the special meeting. Approval of the compensation proposal requires the affirmative vote of at least a majority of the total votes cast at the special meeting by the holders of OceanFirstshares of Partners common stock entitled to vote at the OceanFirst special meeting. The OceanFirst adjournment proposal will be approved if athe majority of the votes cast at the special meeting by the holders of OceanFirstshares of Partners common stock entitled to vote at the OceanFirst special meeting are votedvote in favor of the OceanFirst adjournmentsuch proposal.

The OceanFirstOur board of directors has unanimously approved the mergerAgreement and Plan of Merger, has determined that such agreement and the transactions contemplated thereby,by such agreement, including the integrated mergersfirst-step merger, are advisable, fair to and in the OceanFirst share issuance,best interests of Partners and its stockholders, and unanimously recommends that OceanFirst stockholders vote “FOR” the OceanFirst share issuancemerger proposal, “FOR” the compensation proposal and “FOR” the OceanFirst adjournment proposal.

Your vote is very important. We cannot complete the integrated mergersfirst-step merger unless the OceanFirstPartners stockholders approve the OceanFirst share issuancemerger proposal.

Our priority remains the safety of our stockholders, employees and community. In response to the public health concerns regarding the continuing COVID-19 pandemic, the special meeting will be a virtual meeting held on the Internet. There will be no physical location for the special meeting. Partners stockholders will be able to attend the special meeting online, and, with a control number, vote shares electronically and submit questions during the special meeting by visiting [●] at the meeting date and time. The password for the special meeting is [●], which is also included on your proxy card. If you plan to attend the special meeting online, please see the instructions on page [●] of this proxy statement/prospectus under the heading “The Partners Special Meeting.”

Regardless of whether you plan to attend the OceanFirstvirtual special meeting, please vote as soon as possible. If you hold shares of Partners common stock in your name as a stockholder of record of OceanFirst,Partners, please complete, sign, date and return the accompanying proxy card in the enclosed postage-paid return envelope. You may also vote by telephone or through the Internet by following the instructions on the proxy card. If you hold your shares of Partners common stock in “street name” through a bank, broker or broker,other nominee, please follow the instructions on the voting instruction card furnished by the record holder.

The accompanying proxy statement/prospectus provides a detailed description of the OceanFirst special meeting, the Transactions, the OceanFirst share issuance,mergers, the documents related to the Transactionsmergers and other related matters. We urge you to read this entire jointthe proxy statement/prospectus, including any documents incorporated in this jointthe proxy statement/prospectus by reference, and its annexes carefully and in their entirety.

BY ORDER OF THE BOARD OF DIRECTORS,

Betsy J. Eicher, CPA

Corporate Secretary

Christopher D. MaherPartners Bancorp

President, Chief Executive Officer and Chairman of the Board

TABLE OF CONTENTS

i

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ii

ii

ANNEXES

iii

QUESTIONS AND ANSWERS

The following are some questions that you, as an OceanFirsta Partners stockholder, or a Sun shareholder, may have about the Transactions, the OceanFirst share issuance, the OceanFirst special meetingmergers or the Sun special meeting as applicable, and brief answers to those questions. We urge you to read carefully the remainderall of this joint proxy statement/prospectus because the information in this section does not provide all of the information that might be important to you with respect to the Transactions, the OceanFirst share issuance, the OceanFirst special meetingmergers or the Sun special meeting, as applicable.meeting. For details about where you can find additional important information, please see the section of this joint proxy statement/prospectus entitled “Where You Can Find More Information” beginning on page [●].

Unless the context otherwise requires, references in this joint proxy statement/prospectus to (i) “OceanFirst” refer to OceanFirst Financial Corp., a Delaware corporation, and its subsidiaries, and references to “Sun”(ii) “OceanFirst Bank” refer to Sun Bancorp, Inc.OceanFirst Bank, National Association, (iii) “merger sub” refer to Coastal Merger Sub Corp., a New JerseyMaryland corporation, (iv) “Partners” refer to Partners Bancorp, a Maryland corporation, and its subsidiaries.subsidiaries, (v) “Delmarva Bank” refer to The Bank of Delmarva, a Delaware chartered member bank, and (vi) “Virginia Partners Bank” refer to Virginia Partners Bank, a Virginia chartered member bank.

Q: What are the Transactions?mergers?

A: On November 4, 2021, OceanFirst, Sunthe parent company of OceanFirst Bank, entered into an Agreement and MercuryPlan of Merger Sub Corp. (which we refer to as “Merger Sub”the “merger agreement”) entered intowith Partners, the merger agreement on June 30, 2017. The first-step merger is the first step in a seriesparent company of transactions to combine OceanFirst and Sun, and their respective subsidiary banks, OceanFirstDelmarva Bank and Sun National Bank.Virginia Partners Bank, and merger sub, which, among other things, provides for the strategic acquisition by OceanFirst of Partners.

UnderPursuant to the terms ofand subject to the conditions set forth in the merger agreement:

A copy of the merger agreement is included in this joint proxy statement/prospectus asAnnex A.

The integrated mergers cannot be completed unless, among other things:

Q: Why am I receiving this proxy statement/prospectus?

A: We are delivering this document to you because it is a proxy statement being used by the Partners board of directors (which we refer to as the “Partners board”) to solicit proxies from Partners stockholders in connection with approval of the merger agreement, and the transactions contemplated by the merger agreement, including the first-step merger, and related matters as described in this proxy statement/prospectus.

In order to approve the merger agreement and the transactions contemplated by the merger agreement, including the first-step merger, Partners has called a special meeting of Partners stockholders (which we refer to as the “special meeting”). This document also serves as a notice of the special meeting and describes the proposals to be presented at the special meeting.

This document is also a prospectus of OceanFirst that is being delivered to Partners stockholders because OceanFirst is offering portions of shares of the common stock, par value $0.01 per share, of OceanFirst (which we refer to as the “OceanFirst common stock”) approve the issuance of the shares of OceanFirst common stock in connection with the first-step merger (which we refer to as the “OceanFirst share issuance”).

OceanFirst common stock upon the completion of the first-step merger will instead be entitled to receive an amount in cash (rounded to the nearest cent) baseddetermined by multiplying the fraction of a share (rounded to the nearest thousandth when expressed as a decimal form) of OceanFirst common stock to which the holder would otherwise be entitled by the volume-weighted average trading price (which we refer to as “VWAP”) per share of OceanFirst common stock on the OceanFirst shareNASDAQ Global Select Market (which we refer to as the “Nasdaq”) (as reported by The Wall Street Journal) for the five full trading days ending on the last trading day preceding the closing price.of the mergers.

Q: Will the Sun shareholdersPartners stockholders receive the form of consideration they elect?

A: A Sun shareholderIf a Partners stockholder elects to receive the cash consideration in respect of any shares of Partners common stock held by such Partners stockholder, then such Partners stockholder may not receive the form of consideration that such Sun shareholderPartners stockholder elects in the first-step merger.merger for all the shares of Partners common for which a cash election was made. The allocation and proration provisions of the merger agreement will result, regardless of the elections made, in the total cash consideration being equal to the product of $3.78 and the total number of shares of Sun common stock issued and outstanding immediately prior to the effective time (we refer to such product as the “cash component”no greater than forty percent (40%). Accordingly, upon the conversion of shares of Sun common stock (excluding certain shares of Sun common stock owned by Sun or OceanFirst or any of their respective subsidiaries) into the right to receive the merger consideration, the number of shares of Sun common stock to be converted into the right to receive the cash consideration will equal the quotient of the cash component divided by the per share cash consideration (we refer to such quotient as the “cash conversion number”), and the balance of the shares of SunPartners common stock that are entitled to receive the merger consideration will be convertedbeing convertible into the right to receive the stock consideration.

cash. Pursuant to the allocation and proration provisions of the merger agreement, if the number of shares of SunPartners common stock for which a cash election has been made exceeds the cash conversion number, a pro rata portion of all those shares for which a cash election has been made will instead be converted into the right to receive the stock consideration. Similarly, if the number of shares of Sun common stock for which a cash election has been made is less than the cash conversion number, the outstanding shares of Sun common stock with respect to which no election has been made will be converted to the cash consideration before any outstanding shares of Sun common stock with respect to which a stock election has been made are converted to the cash consideration. The allocation of the consideration payable to the Sun shareholdersPartners stockholders in the first-step merger will not be known until the results of the merger consideration elections made by the Sun shareholdersPartners stockholders are tallied, which will not occur until near or after the closing of the Transactions.mergers. See “Thethe section of this proxy statement/prospectus entitled “The Merger Agreement — Agreement—Merger Consideration”Consideration” beginning on page [●].

Q: How will Sun shareholdersPartners stockholders make their elections to receive either the cash consideration or the stock consideration in the first-step merger?

A: An election form will be mailed to each holder of record of SunPartners common stock as of the business day immediately preceding the date on which the election forms are mailed. The mailing will occur at least 20twenty (20) business days prior to the anticipated election deadline, which is expected to be 5:00 p.m. local time (determined as the city in which the principal office of the exchange agent is located) on the date OceanFirst and SunPartners agree is as near as practicable to two (2) business days before the closing date. OceanFirst will also make an election form available to each Sun shareholderPartners stockholder who, following the date on which the election forms are initially mailed but prior to the election deadline, requests such election form. Each Sun shareholderPartners stockholder should complete and return the election form, along with Sunany Partners stock certificate(s) (or a properly completed notice of guaranteed delivery), according to the instructions included with the form. The election form will be provided to Sun shareholdersPartners stockholders under separate cover and is not being provided with this document.

If you own shares of SunPartners common stock in “street name” through a bank, broker or other nominee and you wish to make an election, you should seek instructions from the bank, broker or other nominee holding your shares concerning how to make an election. If you do not send in the election form with your stock certificate(s) by the election deadline, you will be treated as though you had not made an election.

Q: What happens if a Sun shareholderPartners stockholder does not make a valid election to receive either the cash consideration or the stock consideration?

A: If a Sun shareholderPartners stockholder does not return a properly completed election form by the election deadline specified in the election form, such Sun shareholder shares of SunPartners common stock for which no election was properly made will be (i) considered“non-election” shares and will be(ii) converted into the right to receive the stock consideration or the cash consideration, accordingsubject to (x) a maximum of forty percent (40%) of the shares of Partners common stock being convertible into cash and (y) the allocation and proration provisions of the merger agreement. In the event one form of merger consideration (i.e., cash or shares of OceanFirst common stock) is undersubscribed, shares of Sun common stock for which no election was validly made will be allocated to that form of merger consideration before shares of Sun common stock electing the oversubscribed form of merger consideration will be allocated to the undersubscribed form of merger consideration pursuant to the allocation and proration provisions of the merger agreement. Accordingly, although electing one form of merger consideration will not guarantee you will receive that form of merger consideration for all of your shares of Sun common stock, in the event proration is necessary, electing shares will be allocated the undersubscribed form of consideration only after such consideration is allocated to“non-election” shares.

Q: How will the first-step merger affect SunPartners equity awards?

A: The SunPartners equity awards will be affected as follows:

Restricted Stock AwardsOptions: : At the effective time, each restricted stock award granted by Sun will become fully vested, and each holder of such restricted stock awards will be entitled to receive the merger consideration and will have the right to elect to receive the cash consideration or the stock consideration with respect to each share of Sun common stock held subject to such awards, subject to the allocation and proration provisions of the merger agreement.

Restricted Stock Unit Awards: At the effective time, each restricted stock unit award granted by Sun will be cancelled, and each holder of such restricted stock unit awards will be entitled to receive the merger consideration and will have the right to elect to receive the cash consideration or the stock consideration with respect to each share of Sun common stock held subject to such awards, subject to the allocation and proration provisions of the merger agreement.

Stock Options: At the effective time, each outstanding and unexercised option to purchase Sunshares of Partners common stock granted under the Partners equity plan, whether vested or unvested (which we refer to as “stock options”), will be convertedcanceled, extinguished and exchanged into the right to receive an optionamount of cash (without interest) equal to purchase athe product of (a) the aggregate number of shares of OceanFirstPartners common stock (rounded downissuable upon exercise of such stock option and (b) the excess, if any, of (i) $10.00 over (ii) the per share exercise price of such stock option.

Restricted Stock: At the effective time, each share of restricted stock of Partners granted under Partners’ equity plans or otherwise will be canceled, extinguished and exchanged into the right to receive an amount of cash (without interest) equal to the nearest whole share) determined by multiplying (i)product of (a) the aggregate number of shares of SunPartners common stock subject to such Sunrestricted stock option immediately prior to the effective time by (ii) the exchange ratio; and the exercise price per share of the new option will be equal to the quotient obtained by dividing (a) the per share exercise price for each share of Sun common stock subject to such Sun optionmultiplied by (b) $10.00. In addition, with respect to shares of restricted stock of Partners that vested on an accelerated basis during 2021 in connection with the exchange ratio (rounded upmerger agreement, the holders of such shares have agreed to the nearest whole cent).submit a cash election with respect to these shares.

Q: Will the value of the merger consideration change between the date of this joint proxy statement/prospectus and the time that the first-step merger is completed?completed (which we refer to as the “closing date”)?

A: Yes. Any changesAlthough the exchange ratio in respect of the stock consideration and the cash consideration are fixed, the value of the stock consideration (and, therefore, the aggregate value of the merger consideration) will fluctuate between the date of this proxy statement/prospectus and the effective time with fluctuations in the market price of OceanFirst common stock and will have a corresponding effectnot be known at the time Partners stockholders vote on the value of the stock consideration. In addition, because the value of the per share cash consideration is derived from the OceanFirst share closing price during a period prior to the closing, any changes in the market price of OceanFirst common stock will also have a corresponding effect on the amount of the per share cash consideration. However, the aggregate amount of the cash consideration will not exceed the product of (x) $3.78 and (y) the total number of shares of Sun common stock issued and outstanding immediately prior to the effective time.first-step merger.

Q: How does the OceanFirstPartners board recommend that I vote at the OceanFirst special meeting?

A: The OceanFirstPartners board unanimously recommends that you vote “FOR” the OceanFirst share issuance proposal and “FOR” the OceanFirst adjournment proposal.

Q: How does the Sun board recommend that I vote at the Sun special meeting?

A: The Sun board unanimously recommends that you vote “FOR” the Sun merger proposal, “FOR” the Sun merger-related compensation proposal and “FOR” the Sun adjournment proposal.

Q: When and where areis the meetings?special meeting?

A: The OceanFirstA virtual special meeting of Partners stockholders is scheduled to be held online via live webcast at [●] Eastern Time, on [●], 2022. No physical meeting will be held at 975 Hooper Avenue, Toms River, New Jersey 08753 on [●], 2017, at [●] local time.

The Sun special meeting will be held at 350 Fellowship Road, Suite 101, Mt. Laurel, New Jersey 08054 on [●], 2017, at [●] local time.held.

Q: What do I need to do now?

A: After you have carefully read this entire joint proxy statement/prospectus and have decided how you wish to vote your shares of Partners common stock, please vote your shares of Partners common stock promptly so that your shares of Partners common stock are represented and voted at yourthe special meeting. If you hold your shares of Partners common stock in your name as a stockholder of record, you must complete, sign, date and mail your proxy card in the enclosed postage-paid return envelope as soon as possible. Alternatively, Sun shareholdersyou may vote by telephone or through the Internet or by telephone.Internet. Information and applicable deadlines for voting Sun shares of Partners common stock by telephone or through the Internet or by telephone are set forth in the enclosed Sun proxy card instructions. If you hold your shares of Partners common stock in “street name” through a bank, broker or broker,other nominee, you must direct your bank, broker or brokerother nominee how to vote in accordance with the instructions you have received from your bank, broker or broker.other nominee. “Street name” Partners stockholders who wish to vote in person at theirthe special meeting will need to obtain a legal proxy from the institution or record holder that holds their shares.

Q: What constitutes a quorum for the OceanFirst special meeting?

A: The presence at the OceanFirst special meeting, in person or by proxy, of holders representing at leastPartners stockholders entitled to cast a majority of the outstanding shares of OceanFirst common stock entitled to be votedvotes at the OceanFirst special meeting will constitute a quorum for the transaction of business at the OceanFirst special meeting.

Virtual attendance at the special meeting constitutes “in person” attendance for purposes of establishing a quorum. Once a share of Partners common stock is represented for any purpose at the OceanFirst special meeting, it is deemed present for quorum purposes for the remainder of the OceanFirst special meeting or for any adjournment(s) thereof. adjournment of the special meeting.

Abstentions, and brokernon-votes, if any, will be included in determining the number of shares of Partners common stock present at the meeting for the purpose of determining the presence of a quorum.

Q: What constitutes a quorum for the Sun special meeting?

A: The presence at the Sun special meeting, in person or by proxy, of holders representing at least a majority of the outstanding shares of Sun common stock entitled to be voted at the Sun special meeting will constitute a

quorum for the transaction of business at the Sun special meeting. Once a share is represented for any purpose at the Sun special meeting, it is deemed present for quorum purposes for the remainder of the Sun special meeting or for any adjournment(s) thereof. Abstentions and broker Broker non-votes, if any, will not be included in determining the number of shares of Partners common stock present at the meeting for the purpose of determining the presence of a quorum.quorum because it is expected that all proposals to be voted on at the special meeting will be “non-routine” matters (i.e., matters with respect to which banks, brokers or other nominees do not have discretion to vote shares of Partners common stock, as discussed in more detail below under the question “What is a broker non-vote?”).

Q: What is the vote required to approve each proposal at the OceanFirst special meeting?

A:OceanFirst share issuance proposal: The merger proposal:

OceanFirst adjournment proposal:The compensation proposal:

Q: What is the vote required to approve eachThe adjournment proposal at the Sun special meeting?

A:Sun merger proposal::

Sun merger-related compensation proposal:

Sun adjournment proposal:

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Effect of abstentions and brokernon-votes: If you mark “ABSTAIN” on your proxy, fail to submit a proxy or fail to vote in person at the Sun special meeting, or fail to instruct your bank or broker how to vote with respect to the Sun adjournment proposal, it will have no effect on the Sunvote with respect to the adjournment proposal.

OceanFirst has entered into agreements (which we refer to as the “voting and support agreements”) with (1) Bernard Brown, Sidney R. Brown, Anne Koons, Irwin J. Brown, Jeffrey S. Brown, Shirley Brown, The Bernard A. Brown 2012 Trust, Sidney & Sandy Brown Foundation, Inc., The Four B’s, Interactive Logistics, LLC, National Distribution Centers, L.P., National Freight, Inc. and Vineland Construction Co. (which we refer to collectively as the “Brown family”) and (2) WLR SBI AcquisitionCo, LLC and its ultimate controlling affiliate, WL Ross & Co., LLC (which we refer to collectively as “WLR”) (which we refer to collectively as the “Sun supporting shareholders”), who have agreed, subject to certain exceptions, to, among other things, vote the shares of Sun common stock owned beneficially or of record by each Sun supporting shareholder in favor of the merger proposal. In addition, each Sun supporting shareholder has agreed to vote against any proposal made in competition with the merger proposal, as well as certain other restrictions with respect to the voting and transfer of such Sun supporting shareholder’s shares of Sun common stock.

Based on information set forth in filings with the SEC, as of [●], 2017, made by the Sun supporting shareholders, the Sun supporting shareholders beneficially owned, in the aggregate, [●] shares of Sun common stock (approximately 39% of the outstanding shares of Sun common stock).

Q: Why is my vote important?

A: If you do not vote, or fail to instruct your bank, broker or other nominee how to vote, it will be more difficult for OceanFirst and/or SunPartners to obtain (i) the necessary quorum to hold their respectivethe special meetings.meeting and (ii) the vote to approve the merger proposal. If you are an OceanFirsta Partners stockholder, your failure to submit a proxy or vote in person, or failure to instruct your bank, broker or brokerother nominee how to vote, or your abstention with respect to the OceanFirst share issuancemerger proposal, will not be countedhave the same effect as a vote cast and will have no effect on“AGAINST” the approval of such proposal, even though such approval is a condition to the completionmerger proposal. Approval of the integrated mergers. If you are a Sun shareholder, your failure to submit a proxy or vote in person, or failure to instruct your bank or broker how to vote, or abstention with respect to the Sun merger proposal will not be counted as a vote cast and will have no effect onrequires the approval of such proposal, even though such approval is a condition to the completion of the integrated mergers. The OceanFirst share issuance must be approved by the

affirmative vote of at least a majoritytwo-thirds of all of the total votes entitled to be cast by the OceanFirst stockholders at the OceanFirst special meeting. The Sun merger proposal must be approved by the affirmative vote of a majority of the total votes castmeeting by the holders of Sunshares of Partners common stock entitled to vote at the Sun special meeting. The OceanFirstPartners board unanimously recommends that the OceanFirstPartners stockholders vote “FOR” the OceanFirst share issuancemerger proposal, “FOR” the compensation proposal and the Sun board unanimously recommends that the Sun shareholders vote “FOR” the Sun mergeradjournment proposal.

Q: What is a broker non-vote?

A: A broker non-vote occurs when a bank, broker or other nominee is not permitted to vote without instructions from the beneficial owner of the shares and the beneficial owner fails to provide the bank, broker or other nominee with such instructions. Banks, brokers and other nominees may use their discretion to vote “uninstructed” shares (i.e., shares of record held by banks, brokers or other nominees, but with respect to which the beneficial owner of such shares has not provided instructions on how to vote on a particular proposal) with respect to matters that are considered to be “routine,” but not with respect to “non-routine” matters.

All of the proposals currently scheduled for consideration at the special meeting are “non-routine” matters. If your bank, broker or other nominee holds your shares of Partners common stock in “street name,” such entity will vote your shares of Partners common stock only if you provide instructions on how to vote by complying with the voter instruction form sent to you by your bank, broker or other nominee with this proxy statement/prospectus.

Q: If my shares of Partners common stock are held in “street name” by my bank, broker or broker,other nominee, will my bank, broker or brokerother nominee automatically vote my shares for me?

A: No. Your bank, broker or brokerother nominee cannot vote your shares without instructions from you. You shouldmust instruct your bank, broker or brokerother nominee how to vote your shares in accordance with the instructions provided to you.you if you want your bank, broker or other nominee to vote your shares. Please check the voting form used by your bank, broker or broker.

Q: If I am a participant in Sun’s 401(k) Plan, how will shares owned through such plans be voted?

A: If you hold shares of Sun common stock through the Sun National Bank 401(k) Plan (which we refer to as the “Sun 401(k) Plan”), you will receive a voting instruction card for the Sun 401(k) Plan that reflects all shares you may vote under the Sun 401(k) Plan. Under the terms of the Sun 401(k) Plan, a participant is entitled to vote the shares of Sun common stock held in the Sun Bancorp, Inc. Stock Fund and credited to his or her Sun 401(k) Plan account.

Q: If I am a participant in OceanFirst’s ESOP, OceanFirst’s 401(k) Plan or Ocean Shore’s 401(k) Plan, how will shares owned through such plans be voted?

A: If you participate in the OceanFirst Bank Employee Stock Ownership Plan or the OceanFirst Bank Matching Contribution Employee Stock Ownership Plan (which we collectively refer to as the “OceanFirst ESOP”), the OceanFirst Bank Retirement Plan (which we refer to as the “OceanFirst 401(k) Plan”), or the Ocean Shore Bank Savings and Investment Plan (which we refer to as the “Ocean Shore 401(k) Plan”), which was maintained by Ocean Shore Holding Co. (which we refer to as “Ocean Shore”) prior to November 30, 2016, the date on which OceanFirst completed its acquisition of Ocean Shore (which we refer to as the “Ocean Shore acquisition”), you will receive a voting instruction form for each plan that reflects all shares that you may vote under the particular plan. Under the terms of the OceanFirst ESOP, the OceanFirst ESOP trustee votes all shares held by the OceanFirst ESOP, but each OceanFirst ESOP participant may direct the trustee how to vote the shares of OceanFirst common stock allocated to his or her account. The OceanFirst ESOP trustee, subject to the exercise of its fiduciary responsibilities, will vote all unallocated shares of OceanFirst common stock held by the OceanFirst ESOP and allocated shares for which no voting instructions are received in the same proportion as shares for which it has received timely voting instructions.

Under the terms of the OceanFirst 401(k) Plan and the Ocean Shore 401(k) Plan, respectively, a participant is entitled to provide instructions for all shares credited to his or her OceanFirst 401(k) Plan account or Ocean Shore 401(k) Plan account, as applicable. The trustee will vote all shares for which no directions are given or for which timely instructions were not received in the same proportion as shares for which voting instructions were timely received.

The deadline for returning your voting instructions is [●], 2017.other nominee.

Q: Can I attend the OceanFirst special meeting and/or the Sun special meeting and vote my shares of Partners common stock in person?

A: Yes. All Partners stockholders, of OceanFirst and shareholders of Sun, including stockholders and shareholders of record and stockholders and shareholders who hold their shares “in streetin “street name” through banks, brokers nominees or any other holder of record,nominees, are invited to attend their respective meetings. Holdersthe special meeting. Partners stockholders of record of OceanFirst common stock and Sun common stock can vote in person at the OceanFirst special meeting and Sun special meeting, respectively.meeting. If you are not a Partners stockholder or shareholder of record, you must obtain a proxy, executed in your favor, from the record holder of your shares of Partners common stock, such as a broker, bank or other nominee, to be able to vote in person at your meeting. If you plan to attend your special meeting, you must hold your shares in your own name or have a letter from the record holder of your shares confirming your ownership. In addition, you must bring a form of personal photo identification with you in order to be admitted. OceanFirst and Sun reserve the right to refuse admittance to anyone without proper proof of share ownership or without proper photo identification. The use of cameras, sound recording equipment, communications devices or any similar equipment during the special meetings is prohibited without OceanFirst’s or Sun’s express written consent, respectively.meeting.

Q: Can I change my vote?

A:OceanFirst stockholders: Yes. If you are a holder of record of OceanFirstPartners common stock, you may change your vote or revoke any proxy at any time before it is voted at the special meeting by any of the following methods: (i) signing and returning a proxy card with a later date, (ii) delivering a written revocation letternotice to OceanFirst’sPartners’ corporate secretary or (iii) attending the OceanFirst special meeting in person, notifying the corporate secretary and voting by ballot attelephone or through the OceanFirst special meeting.Internet prior to midnight on [●], 2022. Attendance at the OceanFirstvirtual special meeting (by itself) will not automatically revoke your proxy. A revocation or later-dated proxy received by OceanFirstPartners after the vote will not affect the vote. OceanFirst’sPartners’ corporate secretary’s mailing address is: Betsy J. Eicher, Corporate Secretary, OceanFirst Financial Corp., 975 Hooper Avenue, Toms River, New Jersey 08753.

Sun shareholders: Yes. If you are a holder of record of Sun common stock, you may change your vote or revoke any proxy at any time before it is voted by (i) signing and returning a proxy with a later date (including a proxy given over the Internet or by telephone), (ii) delivering a written revocation letter to Sun’s corporate secretary or (iii) attending the Sun special meeting in person, notifying the corporate secretary and voting by ballot at the Sun special meeting. Attendance at the Sun special meeting by itself will not automatically revoke your proxy. A revocation or later-dated proxy received by Sun after the vote will not affect the vote. Sun’s corporate secretary’s mailing address is: Corporate Secretary, SunPartners Bancorp, Inc., 350 Fellowship Road, Suite 101, Mount Laurel, New Jersey 08054.2245 Northwood Drive, Salisbury, Maryland 21801.

If you hold your shares of OceanFirst common stock or SunPartners common stock in “street name” through a bank, broker or broker,other nominee, you shouldmust contact your bank, broker or brokerother nominee to change your vote or revoke your proxy.

Q: Will OceanFirst be required to submit the OceanFirst share issuance proposal to its stockholders even if the OceanFirst board has withdrawn, modified or qualified its recommendation?

A: Yes. Unless the merger agreement is terminated before the OceanFirst special meeting, OceanFirst is required to submit the OceanFirst share issuance proposal to its stockholders even if the OceanFirst board has withdrawn, modified or qualified its recommendation.

Q: Will Sun be required to submit the Sun merger proposal to its shareholders even if the Sun board has withdrawn, modified or qualified its recommendation?

A: Yes. Unless the merger agreement is terminated before the Sun special meeting, Sun is required to submit the Sun merger proposal to its shareholders even if the Sun board has withdrawn, modified or qualified its recommendation.

Q: What are the U.S. federal income tax consequences of the integrated mergers to Sun shareholders?Partners stockholders?

A: The obligations of Sun and OceanFirst to completeparties expect the integrated mergers are subject to among other customary closing conditions described in this joint proxy statement/prospectus, the receipt by each of Sun and OceanFirst of the opinion of its counsel to the effect that the integrated mergers together will be treated as an integrated transaction that qualifiesqualify as a “reorganization” within the meaning of Section 368(a) of the Internal Revenue Code of 1986, as amended (which we refer to as the “Code”)., and the

obligation of each of OceanFirst and Partners to complete the integrated mergers is conditioned upon the receipt of an opinion of its counsel to that effect. Neither OceanFirst nor Partners currently intends to waive these conditions. Assuming that the integrated mergers qualify as a reorganization within the meaning of Section 368(a) of the Code, the U.S. federal income tax consequences of the integrated mergers to each Sun shareholderPartners stockholder will vary depending on whether such Sun shareholderPartners stockholder receives cash, shares of OceanFirst common stock or a combination thereof in exchange for such Sun shareholder’sPartners stockholder’s shares of SunPartners common stock pursuant to the terms of the merger agreement.

The U.S. federal income tax consequences described above may not apply to all Partners stockholders. You should read the section of this joint proxy statement/prospectus entitled “U.S.“U.S. Federal Income Tax Consequences of the Integrated Mergers”Considerations” beginning on page [●] for a more completedetailed discussion of the U.S. federal income tax consequences ofconsiderations relating to the integrated mergers. Tax matters can be complicated and the tax consequences of the integrated mergers to you will depend on your particular tax situation. You should consult your tax advisor to determine the tax consequences of the integrated mergers to you.

Q: Are Sun shareholdersPartners stockholders entitled to dissenters’ rights?

A: No. Sun shareholdersPartners stockholders are not entitled to exercise dissenters’ rights in connection with the Transactions.first-step merger. For further information, see “The Transactionsthe section of this proxy statement/prospectus entitled “The Mergers — No Dissenters’ Rights” beginning on page [●].

Q: If I am a Sun shareholder,Partners stockholder, should I send in my SunPartners stock certificates now?

A: No. Please do not send in your SunPartners stock certificates with your proxy. Promptly following the completion of the first-step merger, an exchange agent will send you instructions for exchanging SunPartners stock certificates for the applicable merger consideration. See “Thethe section of this proxy statement/prospectus entitled “The Merger Agreement — Conversion of Shares; Exchange of Certificates”Certificates” beginning on page [●].

Q: What should I do if I hold my shares of SunPartners common stock in book-entry form?

A: You are not required to take any special additional actions if your shares of SunPartners common stock are held in book-entry form. Promptly following the completion of the first-step merger, shares of Sunan exchange agent will send you instructions for exchanging Partners common stock held in book-entry form automaticallyfor the applicable merger consideration.

Q: What happens if the first-step merger is not completed?

A: If the first-step merger is not completed, Partners stockholders will be exchangednot receive any consideration for their shares of OceanFirstPartners common stock in book-entry formconnection with the first-step merger. Instead, Partners will remain an independent company and cashPartners common stock will continue to be listed on the Nasdaq under the symbol “PTRS”. In addition, if the merger agreement is terminated under certain circumstances, Partners may be required to pay OceanFirst a termination fee. For a more detailed discussion of the circumstances under which the termination fee will be required to be paid, please see the section of this proxy statement/prospectus entitled “The Merger Agreement — Termination Fee” beginning on page [●].

Q: What happens if I sell my shares of Partners common stock after the record date but before the special meeting?

A: The record date of the special meeting is earlier than both the date of the special meeting and the date that the first-step merger is expected to be completed. If you sell or otherwise transfer your shares of Partners common stock after the record date for the special meeting but before the date of the special meeting, you will retain your right to vote at the special meeting, but you will not have the right to receive the merger consideration to be

received by Partners stockholders in exchange for fractionalthe first-step merger. In order to receive the merger consideration, a Partners stockholder must hold his, her or its shares if any.of Partners common stock through completion of the first-step merger and comply with the transmittal procedures discussed elsewhere in this proxy statement/prospectus.

Q: Whom may I contact if I cannot locate my SunPartners stock certificate(s)?

A: If you are unable to locate your original SunPartners stock certificate(s), prior to closing, you should contact ComputerShare, Sun’sPartners’ transfer agent, Computershare, at [●].(800) 368-5948.

Q: What should I do if I receive more than one set of voting materials?

A: OceanFirstPartners stockholders and Sun shareholders may receive more than one set of voting materials, including multiple copies of this joint proxy statement/prospectus and multiple proxy cards or voting instruction cards. For example, if you hold shares of OceanFirst common stock and/or SunPartners common stock in more than one brokerage account, you will receive a separate voting instruction card for each brokerage account in which you hold such shares.shares of Partners common stock. If you are a holder of record of OceanFirst common stock and/or SunPartners common stock and your shares of Partners common stock are registered in more than one name, you will receive more than one proxy card. In addition, if you are a holder of both OceanFirst common stock and Sun common stock, you will receive one or more separate proxy cards or voting instruction cards for each company. Please complete, sign, date and return each proxy card and voting instruction card that you receive or otherwise follow the voting instructions set forth in this joint proxy statement/prospectus to ensure that you vote every share of OceanFirst common stock and/or SunPartners common stock that you own.

Q: When do you expect to complete the Transactions?mergers?

A: OceanFirst and SunPartners currently expect to complete the Transactions earlymergers in the first quarterhalf of 2018.2022. However, neither OceanFirst nor SunPartners can assure you of when, or if, the Transactionsmergers will be completed. The completion of the integrated mergers is subject to the fulfillmentsatisfaction or waiver of customary closing conditions, including the approval by the OceanFirst stockholdersreceipt of the OceanFirst share issuance proposal, the approval by the Sun shareholdersrequisite vote of the SunPartners stockholders in respect of the merger proposal and the receipt of all requiredthe requisite regulatory approvals.

Q: What happens if the first-step merger is not completed?

A: If the first-step merger is not completed, Sun shareholders will not receive any consideration for their shares in connection with the first-step merger. Instead, Sun will remain an independent public company and its common stock will continue to be listed and traded on the NASDAQ Global Select Market (which we refer to as the “NASDAQ”). In addition, if the merger agreement is terminated in certain circumstances, a termination fee may be required to be paid by either OceanFirst or Sun. For a more detailed discussion of the circumstances under which such payments will be required to be paid, please see the section of this joint proxy statement/prospectus entitled “The Merger Agreement — Termination Fee” beginning on page [●].

Q: Whom should I call with questions?

A:OceanFirst Partners stockholders: If you who (i) have any questions concerning the Transactionsmerger agreement, the mergers or this joint proxy statement/prospectus, (ii) would like additional copies of this joint proxy statement/prospectus or (iii) need help voting yourtheir shares of OceanFirstPartners common stock, pleaseshould contact Investor Relations at (732)240-4500 or OceanFirst’sPartners’ proxy solicitor, Georgeson LLC,Regan & Associates, at (866)296-5716.(212) 587-3005..

Sun shareholders: If you have any questions concerning the Transactions or this joint proxy statement/prospectus, would like additional copies of this joint proxy statement/prospectus or need help voting your shares of Sun common stock, please contact Sun’s Corporate Secretary at (800)691-7701.