SUMMARY

        This summary highlights selected information from this joint proxy statement/prospectus and may not contain all of the information that is important to the shareholders of Pacific Premier and the shareholders of HEOP. To more fully understand the merger and for a more complete description of the legal terms of the merger, you should read carefully this entire joint proxy statement/prospectus, including the merger agreement and the other documents included with this joint proxy statement/prospectus. See "Where You Can Find More Information" beginning on page       . Page references are included in this summary to direct the reader to a more complete description of the topics.

        Throughout this joint proxy statement/prospectus, "Pacific Premier" refers to Pacific Premier Bancorp, Inc. and "HEOP" refers to Heritage Oaks Bancorp. Also, throughout this joint proxy statement/prospectus, the Agreement and Plan of Reorganization, dated as of December 12, 2016, by and between Pacific Premier and HEOP, is referred to as the "merger agreement." The merger of HEOP with and into Pacific Premier is referred to as the "merger" and the Pacific Premier common stock to be issued to HEOP shareholders in consideration for their HEOP common stock, as well as any cash issued in lieu of fractional shares, is referred to as the "merger consideration."

Parties to the Proposed Merger (Page      )

        Pacific Premier Bancorp, Inc.    Pacific Premier is a California-based bank holding company for Pacific Premier Bank, a California-chartered commercial bank. Pacific Premier's principal asset is all of the capital stock of Pacific Premier Bank. Pacific Premier Bank provides banking services to businesses, professionals, real estate investors, non-profit organizations and consumers in its primary market area of Southern California currently through fifteen (15) locations in the cities of Corona, Encinitas, Huntington Beach, Irvine, Los Alamitos, Murrieta, Newport Beach, Orange, Palm Desert, Palm Springs, Redlands, Riverside, San Bernardino and San Diego, California. Pacific Premier Bank's branch in Orange, California will be closed on January 27, 2017. Through Pacific Premier Bank's branches and its Internet website at www.ppbi.com, Pacific Premier Bank offers a broad array of deposit products and services for both businesses and consumer customers, including checking, money market and savings accounts, cash management services, electronic banking services, and on-line bill payment. Pacific Premier Bank also offers a wide array of loan products, such as commercial business loans, lines of credit, U.S. Small Business Administration loans, commercial real estate loans, residential home loans, construction loans and consumer loans. Pacific Premier also offers specialty banking products for homeowners associations and franchise lending nationwide.

        As of September 30, 2016, Pacific Premier had, on a consolidated basis, total assets of $3.75 billion, total stockholders' equity of $449.97 million and total deposits of $3.06 billion. At September 30, 2016, Pacific Premier had gross loans of $3.10 billion, with real estate loans and business loans collateralized by real estate totaling 68% of its gross loan portfolio.

        Pacific Premier's principal executive offices are located at 17901 Von Karman Ave., Suite 1200, Irvine, California 92614 and its telephone number is (949) 864-8000.

        Heritage Oaks Bancorp.    HEOP is a California based bank holding company for Heritage Oaks Bank, a California-chartered banking corporation headquartered in Paso Robles, California. Heritage Oaks Bank is a community-oriented financial services firm which provides banking products and services to small and medium sized businesses and consumers. Products and services are offered primarily through 12 retail branches located on the Central Coast of California, in San Luis Obispo and Santa Barbara Counties and through other direct channels, including a loan production office in Ventura County. As of September 30, 2016, HEOP, on a consolidated basis, had total assets of $1.99 billion, gross loans of $1.3 billion, total shareholders' equity of $215.28 million and total deposits of $1.63 billion.

        HEOP's principal executive offices are located at 1222 Vine Street, Paso Robles, California 93446 and its telephone number is (805) 369-5200.

The Merger (Page      )

        The merger agreement is attached to this joint proxy statement/prospectus as Appendix A, which is incorporated by reference into this joint proxy statement/prospectus. Please read the entire merger agreement. It is the legal document that governs the merger. Pursuant to the terms and conditions set forth in the merger agreement, HEOP will be acquired by Pacific Premier in a transaction in which HEOP will merge with and into Pacific Premier, with Pacific Premier as the surviving institution. Immediately following the consummation of the merger, Heritage Oaks Bank will be merged with and into Pacific Premier Bank, with Pacific Premier Bank as the surviving institution. The parties expect to complete the mergers either by the end of the first quarter of 2017 or early in the second quarter of 2017.

Pacific Premier's Reasons for Merger and Factors Considered by Pacific Premier's Board of Directors (Page      )

        As part of its business strategy, Pacific Premier evaluates opportunities to acquire bank holding companies, banks and other financial institutions, which is an important element of its strategic plan. The acquisition of HEOP is consistent with this strategy. The acquisition of HEOP will (i) extend Pacific Premier's geographic footprint into the Central Coast of California, (ii) create opportunities for Pacific Premier Bank to provide additional products and services to the HEOP customers, and (iii) strengthen Pacific Premier Bank's deposit base with low cost core deposits.

        Based on Pacific Premier's reasons for the merger described in this joint proxy statement/prospectus, including the fairness opinion of D.A. Davidson & Co., or Davidson, an independent investment banking firm, the Pacific Premier board of directors believes that the merger is fair to Pacific Premier's shareholders and in their best interests, and unanimously recommends that Pacific Premier shareholders vote "FOR" approval of the issuance of Pacific Premier common stock in connection with the merger. For a discussion of the circumstances surrounding the merger and the factors considered by Pacific Premier's board of directors in approving the merger agreement, see "The Merger—Pacific Premier's Reasons for the Merger" beginning on page       .

HEOP's Reasons for Merger and Factors Considered by HEOP's Board of Directors (Page      )

        Based on HEOP's reasons for the merger described in this joint proxy statement/prospectus, the HEOP board of directors believes that the merger is fair to HEOP shareholders and in their best interests, and unanimously recommends that HEOP shareholders vote "FOR" approval of the merger agreement. For a discussion of the circumstances surrounding the merger and the factors considered by HEOP's board of directors in approving the merger agreement, see "The Merger—HEOP's Reasons for the Merger" beginning on page       .

Pacific Premier's Financial Advisor Believes that the Merger Consideration Payable by Pacific Premier to HEOP Shareholders in the Merger is Fair, from a Financial Point of View, to Pacific Premier (Page      )

        Davidson delivered its written opinion to Pacific Premier's board of directors that, as of December 12, 2016, and based upon and subject to assumptions made, procedures followed, matters considered and limitations and qualification on the review undertaken set forth in its opinion, the merger consideration to be paid by Pacific Premier to HEOP shareholders in the merger pursuant to the merger agreement was fair, from a financial point of view, to Pacific Premier.

        The full text of the written opinion of Davidson, dated December 12, 2016, which sets forth assumptions made, procedures followed, matters considered and limitations and qualifications on the review undertaken is attached as Appendix B to this joint proxy statement/prospectus. Pacific Premier's shareholders should read the opinion in its entirety. Davidson provided its opinion for the information and assistance of Pacific Premier's board of directors in connection with its consideration of the transaction. The Davidson opinion does not address the underlying business decision to proceed with the merger and is not a recommendation as to how any holder of Pacific Premier common stock should vote on matters to be considered at the Pacific Premier special meeting.

Opinion of HEOP's Financial Advisor (Page      )

        In connection with the merger, Sandler O'Neill & Partners, L.P., or Sandler O'Neill, delivered its oral opinion to HEOP's board of directors, which was subsequently confirmed in writing on December 11, 2016, to the effect that, as of December 11, 2016, and based upon and subject to the assumptions made, procedures followed, matters considered and limitations and qualification on the review undertaken by Sandler O'Neill in providing its opinion, the exchange ratio was fair, from a financial point of view, to the holders of HEOP common stock.

        The full text of the written opinion of Sandler O'Neill, dated December 11, 2016, which sets forth the assumptions made, procedures followed, matters considered and limitations and qualifications on the review undertaken by Sandler O'Neill is attached as Appendix C to this joint proxy statement/prospectus. HEOP's shareholders should read the opinion in its entirety. The opinion of Sandler O'Neill has not been updated prior to the date of this joint proxy statement/prospectus and does not reflect any change in circumstance after December 11, 2016. Sandler O'Neill provided its opinion for the information and assistance of HEOP's board of directors in connection with its consideration of the transaction. The Sandler O'Neill opinion does not address the underlying business decision to proceed with the merger and is not a recommendation as to how any holder of HEOP common stock should vote on matters to be considered at the HEOP special meeting.

HEOP Shareholders Will Receive Shares of Pacific Premier Common Stock for Each Share of HEOP Common Stock Exchanged in the Merger (Page      )

        At the effective time of the merger, each outstanding share of HEOP common stock will, by virtue of the merger and without any action on the part of an HEOP shareholder, be converted into the right to receive 0.3471 shares of Pacific Premier common stock, which is referred to as the exchange ratio. Cash will be paid in lieu of any fractional share interest.

Aggregate Merger Consideration.

        The total consideration to be paid by Pacific Premier to the HEOP shareholders in connection with the merger is referred to in this joint proxy statement/prospectus as the aggregate merger consideration. The term aggregate merger consideration does not include the consideration, if any, payable to holders of (i) options to purchase shares of HEOP common stock, (ii) restricted shares of HEOP common stock, or (iii) restricted stock units of HEOP. In this joint proxy statement/prospectus, we refer to stock options to purchase shares of HEOP's common stock as HEOP options, restricted shares of HEOP common stock as HEOP restricted stock, and restricted stock units as HEOP restricted stock units.

        Upon completion of the merger and based on a $33.65 closing price of Pacific Premier's common stock on December 12, 2016, approximately $401.27 million of aggregate merger consideration will be payable to the HEOP shareholders. The foregoing sentence does not include the payment of cash to the holders of HEOP restricted stock units whose restricted stock units will accelerate in connection with the closing of the merger and assumes that (i) there are 34,355,624 shares of HEOP common

stock outstanding at the closing, (ii) the HEOP shareholders will receive an aggregate of 11,924,837 shares of Pacific Premier common stock after applying the exchange ratio of 0.3471, and (iii) there is no acceleration of vesting of shares of HEOP restricted stock in connection with the closing of the merger that would result in such shares of HEOP restricted stock being converted into the right to receive the merger consideration in the merger.

Fractional Shares.

        No fractional shares of Pacific Premier common stock will be issued, and in lieu thereof, each holder of HEOP common stock who would otherwise be entitled to a fractional share interest will receive an amount in cash, without interest, determined by multiplying such fractional interest by the average closing price per share of Pacific Premier common stock, as reported on the NASDAQ Global Select Market, for the twenty (20) trading days ending on and including the fifth trading day prior to the closing date of the merger, or the Pacific Premier average share price, rounded to the nearest whole cent.

What Will Happen to Outstanding HEOP Options, HEOP Restricted Stock and HEOP Restricted Stock Units (Page      )

HEOP Options.

        Each outstanding and unexercised option to acquire shares of HEOP common stock will be assumed by Pacific Premier and converted automatically into an option to purchase shares of Pacific Premier common stock, which is referred to as a converted HEOP option. The number of shares of Pacific Premier common stock subject to such converted HEOP option shall be equal to the number of shares of HEOP common stock subject to such converted HEOP option immediately prior to the closing of the merger multiplied by the exchange ratio, provided that any fractional shares of Pacific Premier common stock resulting from such multiplication shall be rounded down to the nearest share. The per share exercise price under each such converted HEOP option will be adjusted by dividing the per share exercise price under each such converted HEOP option by the exchange ratio, provided that such exercise price will be rounded up to the nearest cent.

HEOP Restricted Stock Units.

        The board of directors of HEOP intends to accelerate the vesting of HEOP restricted stock units and HEOP restricted stock held by directors, officers and employees of HEOP or its subsidiaries that are not expected to continue with Pacific Premier or its subsidiaries following the closing of the merger.

        Each cash-settled HEOP restricted stock unit which is vested and outstanding as of the closing of the merger will be entitled to receive a single lump sum cash payment equal to the sum of (i) the product of (A) and (B) where (A) equals the product of the number of HEOP restricted stock units and the exchange ratio and (B) equals the average closing price of Pacific Premier common stock during the twenty (20) trading day period ending on the fifth business day prior to the effective time of the merger, which is referred to as the Pacific Premier average share price, plus (ii) any HEOP dividends previously accrued, provided that any fractional HEOP restricted stock units remaining will receive an amount determined by multiplying the fractional share interest by the Pacific Premier average share price, rounded to the nearest whole cent.

        Each unvested cash-settled HEOP restricted stock unit which is outstanding as of the closing of the merger will be assumed by Pacific Premier and will be converted into a right to receive cash payments based upon the values of shares of Pacific Premier common stock. The number of shares of Pacific Premier common stock referenced in each cash-settled HEOP restricted stock unit will be equal to the number of shares of HEOP common stock subject to such cash-settled HEOP restricted stock unit immediately prior to the effective time of the merger multiplied by the exchange ratio, including any fractional shares of Pacific Premier common stock. Any dividends accrued with respect to cash-settled HEOP restricted stock units will continue to be accrued and deferred until such time as the award vests and is paid.

HEOP Restricted Stock.

        Each unvested award of HEOP restricted stock that is outstanding as of the closing of the merger will be assumed by Pacific Premier and converted into shares of Pacific Premier common stock. The number of shares of Pacific Premier common stock subject to each award of HEOP restricted stock will be equal to the number of shares of HEOP common stock subject to such award of HEOP restricted stock immediately prior to the effective time of the merger multiplied by the exchange ratio, provided that any fractional shares of Pacific Premier common stock will be converted into cash in lieu of fractional shares of Pacific Premier common stock. Based on 188,519 shares of unvested HEOP restricted stock, 65,435 shares of Pacific Premier common stock would be issuable to holders of unvested awards of HEOP restricted stock as of that date.

HEOP Performance-Based Restricted Stock Units.

        Pacific Premier will not assume outstanding performance-based HEOP restricted stock units issued for the performance period extending from January 1, 2016 through December 31, 2018. The performance-based HEOP restricted stock units will become vested immediately prior to the effective time of the merger, and each of the holders thereof will be entitled to receive a single lump sum cash payment equal to the product of (A), (B) and (C), where (A) equals 100% of the target number of shares of HEOP common stock subject to the performance-based HEOP restricted stock units, (B) equals the exchange ratio, and (C) equals the Pacific Premier average share price.

Transmittal Materials (Page        )

        After the transmittal materials have been received and processed following the closing of the merger, the HEOP shareholders will be sent the Pacific Premier common stock and any cash in lieu of fractional shares to which they are entitled. If a HEOP shareholder holds shares in street name, he or she will receive information from his or her bank, broker or other nominee advising such HEOP shareholder of the process for receiving the Pacific Premier common stock and any cash in lieu of fractional shares to which he or she is entitled.

        Each HEOP shareholder will need to surrender his or her HEOP common stock certificates or follow instructions for the transfer of shares of HEOP common stock held in book-entry form, to receive the appropriate merger consideration. HEOP shareholders should not send any certificates now. Each HEOP shareholder will receive detailed instructions on how to exchange his or her share certificates or book-entry shares along with transmittal materials promptly following the closing of the merger.

Per Share Market Price and Dividend Information (Page        )

        Shares of Pacific Premier common stock currently trade on the NASDAQ Global Select Market under the symbol "PPBI." Shares of HEOP common stock also trade on the NASDAQ Global Select Market under the symbol "HEOP."

        The following table sets forth the closing sale prices of (i) Pacific Premier common stock as reported on the NASDAQ Global Select Market, and (ii) HEOP common stock as reported on the NASDAQ Global Select Market, on December 12, 2016, the last trading-day before Pacific Premier announced the merger, and on                 , the last practicable trading-day before the distribution of this joint proxy statement/prospectus. To help illustrate the market value of the per share merger consideration to be received by HEOP's shareholders, the following table also presents the equivalent market value per share of HEOP common stock as of December 12, 2016 and                 , which were determined by multiplying the closing price for the Pacific Premier common stock on those dates by the exchange ratio of 0.3471 of a share of Pacific Premier common stock for each share of HEOP common

stock. See "The Merger—The Merger Consideration" beginning on page          for additional information about the merger consideration to be received by holders of HEOP common stock.

        The market price of Pacific Premier common stock and HEOP common stock will fluctuate prior to the date of each of Pacific Premier's and HEOP's special meeting and the date such HEOP shareholder receives the merger consideration. HEOP shareholders should obtain a current price quotation for the shares of Pacific Premier common stock to update the implied value for a share of HEOP common stock.

        Pacific Premier has never declared or paid dividends on its common stock and does not anticipate declaring or paying any cash dividends in the foreseeable future. It is Pacific Premier's current policy to retain earnings to provide funds for use in its business.

        HEOP has been paying a regular quarterly dividend on its common stock. Pursuant to the merger agreement, HEOP may continue to pay its regular quarterly cash dividend equal to the rate paid during the fiscal quarter immediately preceding the date of the merger agreement, with record and payment dates consistent with past practice. See "The Merger—Business Pending the Merger" beginning on page        .

Material Federal Income Tax Consequences of the Merger (Page         )

        The merger is intended to qualify as a "reorganization" within the meaning of Section 368(a) of the Internal Revenue Code of 1986, as amended, which is referred to in this joint proxy statement/prospectus as the Code, and it is a condition to completion of the merger that Pacific Premier and HEOP receive a legal opinion to that effect. If the merger is completed, the merger consideration that will be paid to the holders of HEOP common stock will consist of shares of Pacific Premier common stock (and cash for any fractional shares).

        Assuming the merger qualifies as a reorganization, subject to the limitations and more detailed discussion set forth in "The Merger—Material Federal Income Tax Consequences" of this joint proxy statement/prospectus, a HEOP shareholder that is a U.S. holder generally will not recognize gain or loss on such exchange, other than with respect to cash received in lieu of fractional shares of Pacific Premier common stock.

        Tax matters are complicated, and the tax consequences of the merger to a particular HEOP shareholder will depend in part on such shareholder's individual circumstances. Accordingly, each HEOP shareholder is urged to consult his or her own tax advisor for a full understanding of the tax consequences of the merger to such shareholder, including the applicability and effect of federal, state, local and foreign income and other tax laws.

Date, Time and Location of the Pacific Premier Special Meeting (Page         )

        The Pacific Premier special meeting will be held at         a.m., Pacific Time, on                 , 2017 at 17901 Von Karman Avenue, Suite 1200, Irvine, California 92614. At the Pacific Premier special meeting, Pacific Premier shareholders will be asked to:

•

approve the issuance of Pacific Premier common stock in connection with the merger; and

•

approve a proposal to adjourn the Pacific Premier special meeting if necessary to permit further solicitation of proxies if there are not sufficient votes at the time of the Pacific Premier special meeting to approve the issuance of Pacific Premier common stock in connection with the merger.

Date, Time and Location of the HEOP Special Meeting (Page         )

        The HEOP special meeting will be held at         a.m., Pacific Time, on                 , 2017 at Heritage Oaks Bank's branch office, 545 12th Street, Paso Robles, CA 93446. At the HEOP special meeting, HEOP shareholders will be asked to:

•

approve the merger agreement; and



•

approve a proposal to adjourn the HEOP special meeting if necessary to permit further solicitation of proxies if there are not sufficient votes at the time of the HEOP special meeting to approve the merger agreement.

Record Date and Voting Rights for the Pacific Premier Special Meeting (Page        )

        Each Pacific Premier shareholder is entitled to vote at the Pacific Premier special meeting if he or she owned shares of Pacific Premier common stock as of the close of business on                 , 2017, the record date for the Pacific Premier special meeting. Each Pacific Premier shareholder will have one vote at the Pacific Premier special meeting for each share of Pacific Premier common stock that he or she owned on that date.

        Pacific Premier shareholders of record may vote by mail or by attending the Pacific Premier special meeting and voting in person. Each proxy returned to Pacific Premier by a holder of Pacific Premier common stock, which is not revoked, will be voted in accordance with the instructions indicated thereon. If no instructions are indicated on a signed Pacific Premier proxy that is returned, such proxy will be voted "FOR" approval of the issuance of Pacific Premier common stock in connection with the merger and "FOR" the proposal to adjourn the Pacific Premier special meeting if necessary to permit further solicitation of proxies on the proposal to approve the issuance of Pacific Premier common stock in connection with the merger.

Record Date and Voting Rights for the HEOP Special Meeting (Page         )

        Each HEOP shareholder is entitled to vote at the HEOP special meeting if he or she owned shares of HEOP common stock as of the close of business on                 , 2017, the record date for the HEOP special meeting. Each HEOP shareholder will have one vote at the special meeting for each share of HEOP common stock that he or she owned on that date.

        HEOP shareholders of record may vote by mail or by attending the HEOP special meeting and voting in person. Each proxy returned to HEOP by a holder of HEOP common stock, which is not revoked, will be voted in accordance with the instructions indicated thereon. If no instructions are indicated on a signed HEOP proxy that is returned, such proxy will be voted "FOR" approval of the merger agreement and "FOR" the proposal to adjourn the HEOP special meeting if necessary to permit further solicitation of proxies on the proposal to approve the merger agreement.

Approval of the Issuance of Pacific Premier Common Stock in Connection with the Merger by the Pacific Premier Shareholders Requires that a Majority of the Shares of Pacific Premier Common Stock for which Votes Are Cast at the Pacific Premier Special Meeting to be Voted in Favor of the Issuance of Pacific Premier Common Stock in Connection with the Merger (Page        )

        The affirmative vote of the holders of a majority of shares of Pacific Premier common stock for which votes are cast at the Pacific Premier special meeting is necessary to approve the issuance of the

Pacific Premier common stock in connection with the merger. At the close of business on the record date, there were          shares of Pacific Premier common stock outstanding held by          holders of record. Each holder of record of Pacific Premier common stock on the record date is entitled to one vote for each share held on all matters to be voted upon at the Pacific Premier special meeting. If a Pacific Premier shareholder does not vote, it will have no impact on the proposal to approve the issuance of the Pacific Premier common stock in connection with the merger.

Approval of the Merger Agreement Requires the Affirmative Vote of Holders of a Majority of the Issued and Outstanding Shares of HEOP Common Stock (Page        )

        The affirmative vote of the holders of a majority of the issued and outstanding shares of HEOP common stock is necessary to approve the merger agreement on behalf of HEOP. At the close of business on the record date, there were          shares of HEOP common stock outstanding held by          holders of record. Each holder of record of HEOP common stock on the record date is entitled to one vote for each share held on all matters to be voted upon at the special meeting. If a HEOP shareholder does not vote, it will have the same effect as a vote against the merger agreement.

        Holders of 10,593,567 shares of HEOP common stock, representing approximately 30.8% of the outstanding shares of HEOP common stock, have signed shareholder agreements with Pacific Premier agreeing to vote their shares of HEOP common stock in favor of the merger agreement.

Management of Pacific Premier Owns Shares which may be Voted at the Pacific Premier Special Meeting (Page        )

        As of the record date, the executive officers and directors of Pacific Premier, as a group, held          shares of Pacific Premier common stock, or approximately         % of the outstanding Pacific Premier common stock. While the executive officers and directors of Pacific Premier have not entered into voting agreements agreeing to vote their shares of Pacific Premier common stock in a particular manner, it is anticipated that the executive officers and directors of Pacific Premier will vote consistent with the recommendation of the Pacific Premier board of directors, which is to vote "FOR" the Pacific Premier proposal to approve the issuance of Pacific Premier common stock in connection with the merger.

Management of HEOP Owns Shares which may be Voted at the HEOP Special Meeting (Page        )

        As of the record date, the executive officers and directors of HEOP, as a group, held         shares of HEOP common stock, or approximately         % of the outstanding HEOP common stock, and all of such directors and substantially all of such executive officers have each entered into shareholder agreements with Pacific Premier and HEOP pursuant to which they have agreed, among other things, in their capacity as shareholders of HEOP, to vote their shares of HEOP common stock in favor of the merger agreement. The form of shareholder agreement is attached as Annex A to the merger agreement, which is attached as Appendix A to this joint proxy statement/prospectus.

HEOP is Prohibited from Soliciting Other Offers (Page        )

        HEOP has agreed that, while the merger is pending, it will not solicit, initiate, encourage or, subject to some limited exceptions, engage in discussions with any third party other than Pacific Premier regarding extraordinary transactions such as a merger, business combination or sale of a material amount of its assets or capital stock.

Pacific Premier and HEOP Must Meet Several Conditions to Complete the Merger (Page        )

        Completion of the merger depends on meeting a number of conditions, including the following:

•

shareholders of Pacific Premier must approve the issuance of Pacific Premier common stock in connection with the merger;



•

shareholders of HEOP must approve the merger agreement;



•

Pacific Premier and HEOP must receive all required regulatory approvals for the merger, and any waiting periods required by law must have passed and no such approval may contain any condition (other than conditions or requirements related to remedial actions) that Pacific Premier's board of directors reasonably determines in good faith would materially reduce the economic benefits of the merger to such a degree that, had such condition been known, Pacific Premier, in its reasonable discretion, would not have entered into the merger agreement;



•

there must be no law, injunction or order enacted or issued preventing completion of the merger;



•

the Pacific Premier common stock to be issued in the merger must have been approved for trading on the NASDAQ Global Select Market;



•

the representations and warranties of each of Pacific Premier and HEOP in the merger agreement must be true and correct, subject to the materiality standards provided in the merger agreement;



•

Pacific Premier and HEOP must have complied in all material respects with their respective obligations in the merger agreement;



•

Pacific Premier and HEOP must have received a written opinion that the merger will be treated for federal income tax purposes as a reorganization within the meaning of Section 368(a) of the Code;



•

as of the month end prior to the closing date, the aggregate outstanding balance of HEOP's non-maturity deposits must not be less than $1.25 billion;



•

as of the closing date, HEOP's tangible common equity (as defined and subject to certain specified adjustments set forth in the merger agreement) must not be less than $183.0 million; and



•

all required regulatory approvals for the merger of Heritage Oaks Bank with and into Pacific Premier Bank must be received, any waiting periods required by law must have passed and there must be no law, injunction or order enacted or issued preventing completion of the merger of Heritage Oaks Bank and Pacific Premier Bank.

        Unless prohibited by law, either Pacific Premier or HEOP could elect to waive a condition that has not been satisfied and complete the merger. The parties cannot be certain whether or when any of the conditions to the merger will be satisfied, or waived where permissible, or that the merger will be completed.

Pacific Premier and HEOP Will File Regulatory Applications to Seek Regulatory Approvals to Complete the Merger (Page        )

        To complete the merger, the parties need the prior approval from the Board of Governors of the Federal Reserve System, or the Federal Reserve, and the California Department of Business Oversight, or CA DBO. The U.S. Department of Justice is also able to provide input into the approval process of federal banking agencies and will have between fifteen (15) and thirty (30) days following any approval of a federal banking agency to challenge the approval on antitrust grounds. Pacific Premier and HEOP

will file all necessary applications with the Federal Reserve and the CA DBO. Pacific Premier and HEOP cannot predict whether the required regulatory approvals will be obtained or whether any such approvals will have conditions which would be detrimental to Pacific Premier following completion of the merger.

Pacific Premier and HEOP May Terminate the Merger Agreement (Page        )

        Pacific Premier and HEOP can mutually agree at any time to terminate the merger agreement before completing the merger, even if shareholders of HEOP have already voted to approve it.

        Pacific Premier or HEOP can also terminate the merger agreement:

•

if the other party breaches any of its representations, warranties, covenants or agreements under the merger agreement that (i) cannot be or has not been cured within thirty (30) days of the giving of written notice to the breaching party or parties and (ii) would entitle the non-breaching party or parties not to consummate the merger;



•

if the merger is not consummated by August 30, 2017, except to the extent that the failure to consummate by that date is due to (i) the terminating party's failure to perform or observe its covenants and agreements in the merger agreement, or (ii) the failure of any of the HEOP shareholders (if HEOP is the party seeking to terminate) to perform or observe their respective covenants under the relevant shareholder agreement; or



•

if any required governmental approval of the merger has been denied by final non-appealable action or an application for approval of the merger has been permanently withdrawn at the request of a governmental authority, provided that no party has the right to terminate the merger agreement if the denial is due to the terminating party's failure to perform or observe its covenants in the merger agreement.

        In addition, Pacific Premier may terminate the merger agreement if the shareholders of HEOP do not approve the merger agreement and Pacific Premier may terminate the merger agreement at any time prior to the Pacific Premier special meeting if the board of directors of HEOP withdraws or modifies its recommendation to the HEOP shareholders that the merger agreement be approved in any way which is adverse to Pacific Premier, or breaches its covenants requiring the calling and holding of the HEOP special meeting to consider the merger agreement and prohibiting the solicitation of other offers. Pacific Premier also may terminate the merger agreement if a third party commences a tender offer or exchange offer for 15% or more of the outstanding HEOP common stock and the board of directors of HEOP recommends that HEOP shareholders tender their shares in the offer or otherwise fails to recommend that they reject the offer within a specified period.

        HEOP may terminate the merger agreement if the shareholders of Pacific Premier do not approve the issuance of Pacific Premier common stock in connection with the merger and HEOP may terminate the merger agreement if the HEOP Board has effected a permissible change in recommendation to its shareholders with respect to the merger agreement, provided that HEOP is not then in breach of any representation, warranty, covenant or agreement contained in the merger agreement and, provided further, that any such termination shall not be effective until HEOP has paid Pacific Premier the termination fee required by the merger agreement.

Termination Fee (Page        )

        HEOP must pay Pacific Premier a termination fee of $15.0 million if the merger agreement is terminated under specified circumstances.

Pacific Premier and HEOP May Amend the Merger Agreement (Page        )

        The parties may amend or supplement the merger agreement by written agreement at any time before the merger actually takes place; provided, however, no amendment or supplement that by law requires further approval by the HEOP shareholders may be made after the HEOP special meeting without first obtaining such approval.

HEOP's Directors and Officers Have Some Interests in the Merger that Are in Addition to or Different than the Interests of HEOP Shareholders (Page        )

        HEOP directors and officers have interests in the merger as individuals that are in addition to, or different from, their interests as shareholders of HEOP, which are:

•

HEOP's directors and officers will receive, upon consummation of the merger, options to acquire Pacific Premier common stock in substitution of their HEOP options; in addition, directors and officers of HEOP or its subsidiaries who will be retained by Pacific Premier or its subsidiaries following the consummation of the merger, will receive, upon consummation of the merger, restricted shares of Pacific Premier common stock in substitution of their HEOP restricted stock, and restricted stock units of Pacific Premier in substitution of their HEOP restricted stock units; directors and officers of HEOP and its subsidiaries who will not be retained by Pacific Premier or its subsidiaries following the consummation of the merger will have the vesting of their HEOP restricted stock and HEOP restricted stock units accelerated and (i) the HEOP restricted stock shall be converted into the right to receive the merger consideration and (ii) the cash-settled HEOP restricted stock units shall be converted into the right to receive cash;



•

the agreement of Pacific Premier to honor indemnification obligations of HEOP for a period of six (6) years, as well as to purchase liability insurance for HEOP's directors and officers for six (6) years following the merger, subject to the terms of the merger agreement;



•

cash payments to certain officers of HEOP in the aggregate amount of approximately $4.73 million, on a pre-tax basis, pursuant to the terms of their respective employment-related agreements with HEOP;



•

the appointment of Simone Lagomarsino, the President and Chief Executive Officer of HEOP and Heritage Oaks Bank, Michael Morris, the Chairman of the Board of HEOP and Heritage Oaks Bank, and Michael Pfau, the Vice Chairman of the Board of HEOP and Heritage Oaks Bank, to serve on the boards of directors of Pacific Premier and Pacific Premier Bank effective upon completion of the merger;



•

Robert Osterbauer, Executive Vice President and commercial banking division Manager, North and Agribusiness Lending, with Heritage Oaks Bank, and Brooks Wise, Executive Vice President and commercial banking division Manager, South, with Heritage Oaks Bank, have entered into employment agreements with Pacific Premier Bank, each of which will be effective as of the closing of the merger, which provide compensation to those individuals for continued provision of services to, or employment with, Pacific Premier Bank following the merger; and



•

Effective as of the closing of the merger, Pacific Premier will establish a Community Advisory Board for the Central Coast Region, which shall be comprised of all members of the HEOP board of directors as of the closing of the merger who are willing to so serve.

        The board of directors of Pacific Premier and HEOP were aware of the foregoing interests and considered them, among other matters, in approving the merger agreement and the merger.

Accounting Treatment of the Merger (Page        )

        The merger will be accounted for under the acquisition method of accounting under U.S. generally accepted accounting principles, or GAAP.

Assumption of HEOP Indenture Obligations (Page        )

        Pacific Premier has agreed to assume, or to cause one of its subsidiaries to assume, HEOP's obligations under three trust indentures related to outstanding issuances of junior subordinated debentures.

Shareholders of Pacific Premier and HEOP Have Different Rights (Page        )

        The rights of shareholders of Pacific Premier differ from the rights of shareholders of HEOP. Pacific Premier is incorporated under the laws of the State of Delaware and HEOP is incorporated under the laws of the State of California. The rights of holders of Pacific Premier common stock are governed by the Delaware General Corporation Law, or DGCL, as well as its amended and restated certificate of incorporation, as amended, and amended and restated bylaws. The rights of holders of HEOP common stock are governed by the CGCL, as well as its articles of incorporation, as amended, and bylaws. Following the closing of the merger, shareholders of HEOP will receive shares of Pacific Premier common stock in exchange for their shares of HEOP common stock and become shareholders of Pacific Premier, and their rights as shareholders of Pacific Premier will be governed by Pacific Premier's amended and restated certificate of incorporation, as amended, and amended and restated bylaws and the DGCL.

SELECTED HISTORICAL FINANCIAL DATA

        The following tables present selected consolidated historical financial data of Pacific Premier and selected consolidated historical financial data of HEOP.

Selected Consolidated Historical Financial Data of Pacific Premier

        Set forth below are selected historical financial data derived from Pacific Premier's audited consolidated financial statements as of and for the years ended December 31, 2015, 2014, 2013, 2012 and 2011 and Pacific Premier's unaudited interim consolidated financial statements as of and for the nine months ended September 30, 2016 and 2015. The results of operations for the nine months ended September 30, 2016 are not necessarily indicative of the results of operations for the full year or any other interim period and, in the opinion of Pacific Premier's management, this information reflects all adjustments, consisting of only normal recurring adjustments, necessary for a fair presentation of this data for those dates. You should read the information set forth below, together with Pacific Premier's consolidated financial statements and related notes included in Pacific Premier's Annual Report on Form 10-K for the year ended December 31, 2015 and Quarterly Report on Form 10-Q for the quarter ended September 30, 2016. Pacific Premier's Annual Report on Form 10-K for the year ended December 31, 2015 was filed with the Commission on March 4, 2016 and its Quarterly Report on

Form 10-Q for the quarter ended September 30, 2016 was filed with the Commission on November 9, 2016. Both reports are incorporated by reference in this joint proxy statement/prospectus.

Selected Consolidated Historical Financial Data of HEOP

        Set forth below is certain consolidated financial data of HEOP derived from HEOP's audited consolidated financial statements as of and for the years ended December 31, 2015, 2014, 2013, 2012 and 2011 and HEOP's unaudited interim consolidated financial statements as of and for the nine months ended September 30, 2016 and 2015. The results of operations for the nine months ended September 30, 2016 are not necessarily indicative of the results of operations for the full year or any other interim period and, in the opinion of HEOP's management, this information reflects all adjustments, consisting of only normal recurring adjustments, necessary for a fair presentation of this data for those dates. You should read the information set forth below, together with HEOP's consolidated financial statements and related notes included in HEOP's Annual Report on Form 10-K for the year ended December 31, 2015 and Quarterly Report on Form 10-Q for the quarter ended September 30, 2016. HEOP's Annual Report on Form 10-K for the year ended December 31, 2015 was filed with the Commission on March 4, 2016 and its Quarterly Report on Form 10-Q for the quarter

ended September 30, 2016 was filed with the Commission on November 4, 2016. Both reports are incorporated by reference into this joint proxy statement/prospectus.