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 Independence Bank. To understand the merger fully 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 170. 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. Also, throughout this joint proxy statement/prospectus, the Agreement and Plan of Reorganization, dated as of October 21, 2014, among Pacific Premier, Pacific Premier Bank and Independence Bank, is referred to as the "merger agreement." The merger of Independence Bank with and into Pacific Premier Bank is referred to as the "merger."

Parties to the Proposed Merger (Page 49)

        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 and consumers in its primary market area of Southern California through 13 locations in the cities of San Bernardino, Seal Beach, Huntington Beach, Los Alamitos, Irvine, Newport Beach, Palm Springs, Palm Desert, Encinitas, Point Lorna, San Diego and Seal Beach, California. Through Pacific Premier Bank's branches and its Internet website at www.ppbi.com, Pacific Premier Bank offers a broad array of deposit and loan products and services for both businesses and consumer customers.

        As of September 30, 2014, Pacific Premier had, on a consolidated basis, total assets of $2.0 billion, total stockholders' equity of $197.9 million and total deposits of $1.5 billion. At September 30, 2014, Pacific Premier had real estate loans and business loans collateralized by real estate totaling 72.25% 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.

Recent Developments Involving Pacific Premier

        On August 29, 2014, Pacific Premier completed the issuance of $60 million in aggregate principal amount of 5.75% Subordinated Notes Due 2024 (the "Notes") in a private placement transaction to institutional accredited investors. The Notes bear interest at an annual fixed rate of 5.75%, with the first interest payment on the Notes occurring on March 3, 2015, and interest will be paid semiannually each March 3 and September 3 until September 3, 2024. The net proceeds of the offering were approximately $59 million and are being used for general corporate purposes, including, but not limited to, contribution of capital to Pacific Premier Bank and to support both organic growth as well as opportunistic acquisitions, should appropriate opportunities arise. The Notes are being treated as Tier 2 capital for regulatory capital purposes, subject to applicable limitations. In anticipation of a subordinated debt offering, Pacific Premier obtained ratings from Kroll Bond Rating Agency ("KBRA"). KBRA has assigned investment grade ratings of BBB+ and BBB for Pacific Premier's senior secured debt and subordinated debt, respectively, and a senior deposit rating of A- for Pacific Premier Bank.

        Independence Bank.    Independence Bank is a California-chartered commercial bank that was founded in 2004. Independence Bank operates six full-service banking offices located in Orange and Riverside Counties, California. Independence Bank's regional offices are located in Newport Beach,

San Juan Capistrano, Fountain Valley, Tustin, Riverside and Corona, California. As of September 30, 2014, Independence Bank had total assets of $426.2 million, total stockholders' equity of $48.3 million and total deposits of $357.6 million.

        Independence Bank's principal executive offices are located at 4525 MacArthur Blvd., Newport Beach, California 92660 and its telephone number is (949) 266-6000.

The Merger (Page 49)

        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, Independence Bank will be acquired by Pacific Premier whereby Independence Bank will merge with and into Pacific Premier Bank, with Pacific Premier Bank as the surviving institution. The parties expect to complete the merger in the first quarter of 2015.

Pacific Premier's Reasons for Merger and Factors Considered by Pacific Premier's Board of Directors (Page 51)

        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 Independence Bank is consistent with this strategy. Pacific Premier believes that the acquisition of Independence Bank will (i) create opportunities for the bank to provide products and services to the Independence Bank customers, (ii) strengthen Pacific Premier Bank's deposit base with low cost core deposits and (iii) solidify its brand within its existing footprint between Orange County and the broader Coachella Valley.

        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 51.

Independence Bank's Reasons for Merger and Factors Considered by Independence Bank's Board of Directors (Page 53)

        Based on Independence Bank's reasons for the merger described in this joint proxy statement/prospectus, the Independence Bank board of directors believes that the merger is fair to Independence Bank shareholders and in their best interests, and unanimously recommends that Independence Bank shareholders vote "FOR" approval of the merger agreement. For a discussion of the circumstances surrounding the merger and the factors considered by Independence Bank's board of directors in approving the merger agreement, see "The Merger—Independence Bank's Reasons for the Merger" beginning on page 53.

Pacific Premier's Financial Advisor Believes that the Merger Consideration payable by Pacific Premier to Independence Bank shareholders in the Merger is Fair, From a Financial Point of View, to Pacific Premier (Page 55)

        Davidson delivered its written opinion to Pacific Premier's board of directors that, as of October 20, 2014, 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 Independence Bank 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 October 20, 2014, 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.

Independence Bank's Financial Advisor Provided a Fairness Opinion to Independence Bank's Board of Directors in connection with the Merger (Page 69)

        In connection with the merger, Independence Bank's financial advisor, Keefe, Bruyette & Woods, Inc. ("KBW"), delivered a written opinion, dated October 20, 2014, to the Independence Bank board of directors as to the fairness, from a financial point of view and as of the date of the opinion, to the holders of Independence Bank common stock of the merger consideration in the proposed merger. The full text of the opinion, which describes the procedures followed, assumptions made, matters considered, and qualifications and limitations on the review undertaken by KBW in preparing the opinion, is attached as Appendix C to this joint proxy statement/prospectus. The opinion was for the information of, and was directed to, the Independence Bank board (in its capacity as such) in connection with its consideration of the financial terms of the merger. The opinion did not address the underlying business decision of Independence Bank to engage in the merger or enter into the merger agreement or constitute a recommendation to the Independence Bank board in connection with the merger, and it does not constitute a recommendation to any holder of Independence Bank common stock or any shareholder of any other entity as to how to vote in connection with the merger or any other matter (including, with respect to holders of Independence Bank common stock, what election any such shareholder should make with respect to the per share stock consideration or the per share cash consideration).

Independence Bank Shareholders Will Receive Cash or Shares of Pacific Premier Common Stock for Each Share of Independence Bank Common Stock Exchanged in the Merger (Page 82)

        At the effective time of the merger, each outstanding share of Independence Bank common stock (subject to certain exceptions) will, by virtue of the merger and without any action on the part of an Independence Bank shareholder, be converted into the right to receive, subject to possible adjustment as discussed below, (i) $13.75 in cash, without interest, or the per share cash consideration, or (ii) 0.9259 shares of Pacific Premier common stock, subject to upward or downward adjustment based on changes in the stock price of Pacific Premier common stock as described below, or the per share stock consideration. Cash will be paid in lieu of any fractional share interest.

        Independence Bank shareholders will have the opportunity to elect the form of consideration to be received for all shares of Independence Bank common stock held by them, whether all stock, all cash or a combination of stock and cash, subject to the allocation procedures provided for in the merger agreement, which are intended to ensure that 90% of the value of the aggregate merger consideration is paid in the form of shares of Pacific Premier common stock, and 10% of the aggregate merger consideration is paid in cash.

Per Share Cash Consideration.

        The cash portion of the aggregate merger consideration is not subject to adjustment. Based on the allocation procedures which will provide for 10% of the aggregate merger consideration to be paid in cash, the cash portion of the aggregate merger consideration would be approximately $7.2 million, or $13.75 for each share of Independence Bank common stock.

Per Share Stock Consideration and Possible Adjustment.

        The per share stock consideration of 0.9259 shares of Pacific Premier common stock is subject to possible downward or upward adjustment based on the average closing stock price of Pacific Premier common stock for the 10 trading day period ending on the fifth business day prior to the effective time of the merger, or the Pacific Premier average share price. If the Pacific Premier average share price is greater than $16.335, then the per share stock consideration will be adjusted downward to equal (i) $15.125 divided by (ii) the Pacific Premier average share price, rounded to the nearest ten-thousandth. If the Pacific Premier average share price is less than $13.365, then the per share stock consideration will be adjusted upward to equal (x) $12.375 divided by (y) the Pacific Premier average share price, rounded to the nearest ten-thousandth. The thresholds for the Pacific Premier average share price identified above of $16.335 and $13.365 were based on a 10% increase and decrease, respectively, from a share price of Pacific Premier common stock of $14.85. Assuming a closing date of December 10, 2014, which is the date immediately prior to the date of filing of this joint proxy statement/prospectus, the Pacific Premier average share price would be calculated to be $16.07, and therefore no adjustment would occur to the per share stock consideration. To the extent that no adjustment to the per share stock consideration occurs and based on the allocation procedures, which provide that 90% of the value of the aggregate merger consideration will be paid in shares of Pacific Premier common stock, the stock portion of the aggregate merger consideration would amount to approximately $70.7 million, based on a $16.19 closing price of Pacific Premier's common stock on December 10, 2014 and will result in 4,365,843 shares of Pacific Premier common stock being issued.

Aggregate Merger Consideration.

        The total consideration to be paid by Pacific Premier in connection with the merger to the Independence Bank shareholders, the holders of stock options to purchase shares of Independence Bank's common stock and the holders of warrants to purchase shares of Independence Bank's common stock is referred to in this joint proxy statement/prospectus as the aggregate merger consideration. In this joint proxy statement/prospectus, we refer to each stock option to purchase shares of Independence Bank's common stock as an Independence Bank option and each warrant to purchase shares of Independence Bank's common stock as an Independence Bank warrant. Under the terms of the merger agreement, 10% of the aggregate merger consideration is to be paid in cash and 90% of the value of the aggregate merger consideration is to be paid in shares of Pacific Premier common stock.

        Upon completion of the merger and based on a $16.19 closing price of Pacific Premier's common stock on December 10, 2014, approximately $77.9 million of aggregate merger consideration will be payable to the Independence Bank shareholders, the holders of Independence Bank options and the holders of Independence Bank warrants. For Independence Bank shareholders, this implies an aggregate consideration of $14.99 per common share, assuming a 100% stock election or cash and stock consideration of $14.96 per common share. The foregoing sentence assumes (i) that the holders of Independence Bank options and the holders of Independence Bank warrants will receive 100% cash consideration in connection with the cancellation of their respective Independence Bank options and Independence Bank warrants based on a $13.75 price per share and that there are 672,250 Independence Bank options outstanding at the closing with a weighted average exercise price of $7.75 per share and 206,975 Independence Bank warrants outstanding at the closing with a weighted average exercise price of $5.50 per share, (ii) there are 4,821,628 shares of Independence Bank common stock

outstanding at the closing, (iii) the Independence Bank shareholders will receive the remaining amount of aggregate per share cash consideration after deducting the cash paid to the holders of Independence Bank options and the holders of Independence Bank warrants, at an amount of $13.75 per common share, and (iv) the Independence Bank shareholders will receive an aggregate of 4,365,843 shares of Pacific Premier common stock after applying the exchange ratio of 0.9259 to Independence Bank shareholders receiving stock consideration and that there is no adjustment to the per share stock consideration.

Merger Consideration Example.

        The following table illustrates what the exchange ratio, the related per share stock consideration, the per share cash consideration and the aggregate stock, aggregate cash and aggregate merger consideration values would be depending upon changes to the Pacific Premier average share price, ranging from 21% above $14.73 per share, which was the closing price per share of Pacific Premier's common stock on October 21, 2014, the date prior to announcement of entry into the merger agreement by the parties, to 19% below $14.73 per share. The table also illustrates the values which would result to the extent that the Pacific Premier average share price reached the cap or collar price of $16.335 or $13.365, respectively, which would constitute an 11% increase and 9% decrease, respectively, from a share price of Pacific Premier common stock of $14.73. The following table assumes there are 4,821,628 shares of Independence Bank common stock outstanding as of the closing date. The table reflects that the aggregate merger consideration paid will consist of 10% cash and 90% shares of Pacific Premier common stock and that the per share cash consideration is $13.75. As described below under "The Merger—The Merger Consideration—Allocation Procedures" beginning on page 86, regardless of whether an Independence Bank shareholder makes an all-cash election or an all-stock election, that Independence Bank shareholder may nevertheless receive a mix of cash and shares of Pacific Premier common stock as merger consideration. The table does not reflect the fact that cash will be paid instead of fractional shares.

        The implied value of the per share stock consideration based on the exchange ratio continuing to be 0.9259 shares of Pacific Premier common stock for one share of Independence Bank common stock on December 10, 2014 was $14.99, which amount was based on the closing price per share of Pacific Premier common stock on that date. The value of the stock portion of the aggregate merger consideration will (i) fluctuate based on the market price of Pacific Premier common stock and such value on the closing date of the merger and (ii) be subject to upward or downward adjustment if the Pacific Premier average share price is either less than $13.365 or greater than $16.335, and therefore, the value of the stock portion of the merger consideration will not be known at the time the Independence Bank shareholders vote on the merger agreement or elect the form of merger consideration the Independence Bank shareholders would like to receive or at the time the Pacific Premier shareholders vote on the issuance of the Pacific Premier common stock in connection with the merger. Pacific Premier's common stock is listed on the Nasdaq Global Select Market under the symbol "PPBI." Shareholders or Independence Bank and Pacific Premier should obtain current market quotations for the Pacific Premier common stock.

        Upon completion of the merger, and based on 4,821,628 shares of Independence Bank common stock outstanding as of the date of this joint proxy statement/prospectus and assuming there is no adjustment to the per share stock consideration, Independence Bank shareholders are expected to receive 4,365,843 shares of Pacific Premier common stock. Following the completion of the merger, and based on 16,894,216 shares of Pacific Premier common stock outstanding as of December 10, 2014, the former Independence Bank shareholders will own approximately 20.5% of the outstanding shares of Pacific Premier common stock and the current shareholders of Pacific Premier will own the remaining approximately 79.5% of the outstanding shares of Pacific Premier common stock.

        The examples above are illustrative only and are based on the assumptions indicated. The value of the stock portion of the merger consideration that an Independence Bank shareholder actually receives will be based on the actual Pacific Premier average share price calculated prior to completion of the merger. The actual Pacific Premier average share price may be outside the range of the amounts set forth above, and as a result, the actual value of the stock portion of the merger consideration per share of Independence Bank common stock may not be shown in the above table.

Fractional Shares.

        No fractional shares of Pacific Premier common stock will be issued, and in lieu thereof, each holder of Independence Bank 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 $13.75, which amount reflects per share cash consideration, rounded to the nearest whole cent.

What Will Happen to Outstanding Independence Bank Stock Options (Page 87)

        Pursuant to the terms of the merger agreement, each Independence Bank option that is outstanding and unexercised will be cancelled in accordance with the Independence Bank 2014 Stock Option Plan and the Independence Bank 2004 Stock Option Plan, as the case may be, referred to in this joint proxy statement/prospectus as the Independence Bank Stock Option Plans, upon the closing of the merger and each holder of such Independence Bank option will be entitled to receive from Pacific Premier, as soon as reasonably practicable after the effective time of the merger, but in no event later than three (3) days after such effective time, a single lump sum cash payment equal to the product of (i) the aggregate number of shares of Independence Bank common stock subject to such Independence Bank option immediately prior to the closing of the merger, and (ii) the excess, if any, of the per share cash consideration over the exercise price per share of such Independence Bank option, less any applicable taxes required to be withheld with respect to such payment. If the exercise price per share of any such Independence Bank option is equal to or greater than the per share cash

consideration, such Independence Bank option will be canceled without any cash payment being made in respect thereof.

What Will Happen to Outstanding Independence Bank Warrants (Page 88)

        Pursuant to the terms of the merger agreement, subject to entry into an agreement with Pacific Premier by each holder of an Independence Bank warrant, each Independence Bank warrant contract that is outstanding and not exercised and has not expired by its terms at the closing of the merger will be purchased by Pacific Premier and cancelled in exchange for the right to receive from Pacific Premier a single lump sum cash payment equal to the product of (i) the number of shares of Independence Bank common stock subject to such Independence Bank warrant immediately prior to the closing of the merger, and (ii) the excess, if any, of the per share cash consideration over the exercise price per share of such Independence Bank warrant, less any applicable taxes required to be withheld with respect to such payment. If the exercise price per share of any such Independence Bank warrant is equal to or greater than the per share cash consideration, such Independence Bank warrant, will be canceled without any cash payment being made in respect thereof. Any warrant holder who fails to enter into an agreement with Pacific Premier will have his or her warrant assumed by Pacific Premier.

When and How to Choose the Method of Payment for Your Independence Bank Shares (Page 85)

        Shares of Independence Bank common stock will be exchanged for either shares of Pacific Premier common stock, cash or a combination of Pacific Premier stock and cash, as chosen by each Independence Bank shareholder, subject to the election and allocation procedures discussed herein and described in detail in the merger agreement. A form for making an election will be sent to the Independence Bank shareholders under separate cover no later than the date that this joint proxy statement/prospectus is mailed to holders of record of Independence Bank common stock. The election form permits each Independence Bank shareholder:

•

to elect to receive shares of Pacific Premier common stock in exchange for all shares of Independence Bank common stock held by such Independence Bank shareholder, plus cash in lieu of any fractional share interest;



•

to elect to receive cash in exchange for all shares of Independence Bank common stock held by such Independence Bank shareholder;



•

to elect to receive shares of Pacific Premier common stock with respect to some of the shares of Independence Bank common stock by such Independence Bank shareholder and cash with respect to the remaining shares of Independence Bank common stock held by such Independence Bank shareholder; or



•

to indicate that such Independence Bank shareholder makes no election with respect to the merger consideration to be received by the Independence Bank shareholder in exchange for the shares of Independence Bank common stock held by such Independence Bank shareholder.

        In order to make an effective election, each Independence Bank shareholder should complete the election form and return it as instructed with the stock certificates representing the shares of Independence Bank common stock held by such Independence Bank shareholder.

        The election form must be received by the designated exchange agent by 5:00 p.m., Pacific Time, on January 16, 2015. After the election deadline, the Independence Bank shareholders will not be able to change their elections and each Independence Bank shareholder will be bound to the election he or she has made, subject to the allocation procedures described in this this joint proxy statement/prospectus.

        The election choices of each Independence Bank shareholder will be honored to the extent possible, but because of the overall limitation on the amount of cash and shares of Pacific Premier common stock available, whether such Independence Bank shareholder receives the amount of cash or stock requested will depend in part on how many other Independence Bank shareholders submit elections and how many choose to receive cash and how many choose to receive stock. Because 90% of the value of the aggregate merger consideration will paid in the form of shares of Pacific Premier common stock and 10% of the aggregate merger consideration will be paid in cash, Independence Bank shareholders may not receive exactly the form of consideration that they elect and may receive a pro rata amount of cash and Pacific Premier common stock.

        Pacific Premier will not issue fractional shares. Instead, Independence Bank shareholders who receive Pacific Premier common stock will receive the value of any fractional share interest in cash, without interest, determined by multiplying such fractional interest by $13.75, which amount reflects the per share cash consideration, rounded to the nearest whole cent.

        After the election form and related transmittal materials have been received and processed and following the closing of the merger, the Independence Bank shareholders will be sent the cash and/or Pacific Premier common stock to which they are entitled. If an Independence Bank shareholder holds shares in street name, he or she will receive information from his or her broker or other holder of record advising such Independence Bank shareholder of the process for receiving the cash and/or Pacific Premier common stock to which he or she is entitled.

        Each Independence Bank shareholder will need to surrender his or her Independence Bank common stock certificates to receive the appropriate merger consideration, but such Independence Bank shareholder should not send any certificates now. Each Independence Bank shareholder will receive detailed instructions on how to exchange his or her shares along with an election form and transmittal materials.

Per Share Market Price and Dividend Information (Page 116)

        Shares of Pacific Premier common stock currently trade on the Nasdaq Global Select Market under the symbol "PPBI." Shares of Independence Bank common stock are quoted on the OTC Market Group's OTCQB platform, which is the middle tier of the OTC Market Group, under the symbol "IDPK."

        The following table sets forth the closing sale prices of (i) Pacific Premier common stock as reported on the Nasdaq Stock Market, and (ii) Independence Bank common stock as quoted on the OTCQB, on October 22, 2014, the last trading-day before Pacific Premier announced the merger, and on December 10, 2014, the last practicable trading-day before the distribution of this joint proxy statement/prospectus. To help illustrate the market value of the per share stock consideration to be received by Independence Bank's shareholders, the following table also presents the equivalent market value per share of Independence Bank common stock as of October 22, 2014 and December 10, 2014, which were determined by multiplying the closing price for the Pacific Premier common stock on those dates by the exchange ratio of 0.9259 of a share of Pacific Premier common stock for each share of Independence Bank common stock. The equivalent market value per share of Independence Bank common stock presented below does not reflect the possible upward or downward adjustment if the Pacific Premier average share price is either less than $13.365 or greater than $16.335, or the per share cash consideration that also will be received by holders of Independence Bank common stock. See

"The Merger—The Merger Consideration" beginning on page 82 for additional information about the merger consideration to be received by holders of Independence Bank common stock.

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

        Independence Bank has never declared or paid dividends on its common stock. As a California-chartered bank, Independence Bank is subject to bank regulatory restrictions on payment of dividends. Pursuant to the merger agreement, Independence Bank has certain restrictions on the payment of dividends to its shareholders pending the closing of the merger. See "The Merger—Business Pending the Merger" beginning on page 93.

Material Federal Income Tax Consequences of the Merger (Page 106)

        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 Independence Bank receive a legal opinion to that effect. If the merger is completed, the merger consideration that will be paid to the holders of Independence Bank common stock will include shares of Pacific Premier common stock (including cash for any fractional shares) and cash.

        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, an Independence Bank shareholder that is a U.S. holder that receives solely shares of Pacific Premier common stock in exchange for all of its shares of Independence Bank common stock 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. An Independence Bank shareholder that is a U.S. Holder that receives solely cash in exchange for all of its shares of Independence Bank common stock generally will recognize gain or loss in connection with such exchange. An Independence Bank shareholder that receives shares of Pacific Premier common stock and cash in exchange for all of its shares of Independence Bank common stock generally will recognize gain (but not loss) on such exchange.

        Tax matters are complicated, and the tax consequences of the merger to a particular Independence Bank shareholder will depend in part on such shareholder's individual circumstances. Accordingly, each Independence Bank shareholder is urged to consult his or her own tax advisor for a full understanding of the tax consequences of the merger to you, 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 41)

        The Pacific Premier special meeting will be held at 8:00 a.m., Pacific Time, on January 23, 2015, 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 Independence Bank Special Meeting (Page 45)

        The Independence Bank special meeting will be held at 8:00 a.m., Pacific Time, on January 23, 2015, at 4525 MacArthur Blvd., Newport Beach, California 92660. At the Independence Bank special meeting, Independence Bank shareholders will be asked to:

•

approve the merger agreement; and



•

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

Record Date and Voting Rights for the Pacific Premier Special Meeting (Page 41)

        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 December 10, 2014, 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 Independence Bank Special Meeting (Page 45)

        Each Independence Bank shareholder is entitled to vote at the Independence Bank special meeting if he or she owned shares of Independence Bank common stock as of the close of business on December 10, 2014, the record date for the Independence Bank special meeting. Each Independence Bank shareholder will have one vote at the special meeting for each share of Independence Bank common stock that he or she owned on that date.

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

proposal to adjourn the Independence Bank 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 43)

        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 16,894,216 shares of Pacific Premier common stock outstanding held by 2,305 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 Majority of the Issued and Outstanding Shares of Independence Bank Common Stock (Page 47)

        The affirmative vote of the holders of a majority of the issued and outstanding shares of Independence Bank common stock is necessary to approve the merger agreement on behalf of Independence Bank. At the close of business on the record date, there were 4,821,628 shares of Independence Bank common stock outstanding held by 830 holders of record. Each holder of record of Independence Bank 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 Independence Bank shareholder does not vote, it will have the same effect as a vote against the merger agreement.

        Holders of 636,566 shares of Independence Bank common stock, representing approximately 13.2% of the outstanding shares of Independence Bank common stock, have signed shareholder agreements with Pacific Premier agreeing to vote their shares of Independence Bank common stock in favor of the merger agreement.

Management of Pacific Premier Owns Shares Which May Be Voted at the Pacific Premier Special Meeting

        As of the record date, the executive officers and directors of Pacific Premier, as a group, held 451,055 shares of Pacific Premier common stock, or approximately 2.7% 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, we anticipate 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 Independence Bank Owns Shares Which May Be Voted at the Independence Bank Special Meeting (Page 102)

        As of the record date, the executive officers and directors of Independence Bank, as a group, held 636,566 shares of Independence Bank common stock, or approximately 13.2% of the outstanding Independence Bank common stock and have each entered into shareholder agreements with Pacific Premier and Independence Bank pursuant to which they have agreed, among other things, in their capacity as shareholders of Independence Bank, to vote their shares of Independence Bank 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.

Independence Bank's Shareholders Have Dissenters' Rights (Page 112)

        Under the California General Corporation Law, or CGCL, holders of Independence Bank common stock have the right to demand appraisal of their shares of Independence Bank common stock in connection with the merger and to receive, in lieu of the merger consideration, payment in cash, for the fair value of their shares of Independence Bank common stock. Any Independence Bank shareholder electing to exercise dissenters' rights must not have voted his, her or its shares of Independence Bank common stock "FOR" approval of the merger agreement and must comply with the provisions of the CGCL in order to perfect its rights of dissent and appraisal. Strict compliance with the statutory procedures is required to perfect dissenters' rights. These procedures are described later in this joint proxy statement/prospectus, and a copy of the relevant provisions of California law is attached as Appendix D.

Independence Bank is Prohibited from Soliciting Other Offers (Page 96)

        Independence Bank 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 assets or capital stock.

Pacific Premier and Independence Bank Must Meet Several Conditions to Complete the Merger (Page 89)

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

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



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shareholders of Independence Bank must approve the merger agreement;



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Pacific Premier and Independence Bank 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 that Pacific Premier's board of directors reasonably determines in good faith would materially reduce the benefits of the merger to such a degree that, had such condition been known, Pacific Premier would not have entered into the merger agreement;



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



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



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



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



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Pacific Premier and Independence Bank shall 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 Internal Revenue Code;

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as of the closing date, Independence Bank's average total deposits during a specified period and tangible common equity capital must not be less than $310,150,000 and $47,250,000, respectively, subject to certain specified assumptions set forth in the merger agreement; and



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dissenting shares must not represent 10% or more of the outstanding shares of Independence Bank common stock.

        Unless prohibited by law, either Pacific Premier or Independence Bank 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 Independence Bank Have Filed Regulatory Applications to seek Regulatory Approvals to Complete the Merger (Page 92)

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

Pacific Premier, Pacific Premier Bank and Independence Bank may Terminate the Merger Agreement (Page 99)

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

        Pacific Premier or Independence Bank can also terminate the merger agreement:

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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;



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if the merger is not consummated by June 30, 2015, 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 Independence Bank shareholders (if Independence Bank is the party seeking to terminate) to perform or observe their respective covenants under the relevant shareholder agreement;



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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;



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if the shareholders of Pacific Premier do not approve the issuance of Pacific Premier common stock in connection with the merger; or



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if the shareholders of Independence Bank do not approve the merger agreement.

        In addition, Pacific Premier may terminate the merger agreement at any time prior to the Pacific Premier special meeting if the board of directors of Independence Bank withdraws or modifies its recommendation to the Independence Bank 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 a meeting of shareholders 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 Independence Bank common stock and the board of directors of Independence Bank recommends that Independence Bank shareholders tender their shares in the offer or otherwise fails to recommend that they reject the offer within a specified period.

Termination Fee (Page 100)

        Independence Bank must pay Pacific Premier a termination fee of $3.5 million if the merger agreement is terminated under specified circumstances.

Pacific Premier, Pacific Premier Bank and Independence Bank May Amend the Merger Agreement (Page 99)

        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 may be made after the Independence Bank special meeting which by law requires further approval by the shareholders of Independence Bank without obtaining such approval.

Independence Bank's Directors and Officers Have Some Interests in the Merger that Are in Addition to or Different than Your Interests (Page 102)

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

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Independence Bank's directors and executive officers will receive an aggregate amount of approximately $3,222,568 in connection with the cancellation of their Independence Bank options and purchase of their Independence Bank warrants upon the consummation of the merger;



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the agreement of Pacific Premier to honor indemnification obligations of Independence Bank for a period of four (4) years, as well as to purchase liability insurance for Independence Bank's directors and officers for four (4) years following the merger, subject to the terms of the merger agreement; and



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cash payments to certain executive officers of Independence Bank in the aggregate amount of $1,458,500, on a pre-tax basis, pursuant to the terms of their respective employment agreements with Independence Bank.

        The board of directors of Pacific Premier and Independence Bank 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 110)

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

Shareholders of Pacific Premier and Independence Bank Have Different Rights (Page 161)

        The rights of shareholders of Pacific Premier differ from the rights of shareholders of Independence Bank. Pacific Premier is incorporated under the laws of the State of Delaware and Independence Bank 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 and amended and restated bylaws, and the rights of holders of Independence Bank common stock are governed by the California Financial Code and the CGCL, as well as its articles of incorporation and bylaws. Shareholders of Independence Bank who will receive shares of Pacific Premier common stock in exchange for their shares of Independence Bank 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 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 historical financial data of Independence Bank.

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, 2013, 2012, 2011, 2010 and 2009 and Pacific Premier's unaudited interim consolidated financial statements as of and for the nine months ended September 30, 2014 and 2013. The results of operations for the nine months ended September 30, 2014 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, 2013 and Quarterly Report on Form 10-Q for the quarter ended September 30, 2014. Pacific Premier's Annual Report on Form 10-K for the year ended December 31, 2013 was filed with the Commission on March 17, 2014 and its Quarterly Report on Form 10-Q for the quarter ended September 30, 2014 was filed with the Commission on November 6, 2014. Both reports are incorporated by reference in this joint proxy statement/prospectus.

Selected Historical Financial Data of Independence Bank

        Set forth below is certain consolidated financial data of Independence Bank as of and for the years ended December 31, 2013 and December 31, 2012 and as of and for the nine months ended September 30, 2014 and 2013. The unaudited results of operations for the nine months ended September 30, 2014 and 2013 are not necessarily indicative of the results of operations for the full year or any other interim period. Independence Bank's management prepared the unaudited consolidated information as of and for the nine months ended September 30, 2014 and 2013 on the same basis as it prepared Independence Bank's audited financial statements as of and for the years ended December 31, 2013 and 2012. In the opinion of Independence Bank's management, this unaudited consolidated information reflects all adjustments, consisting of only normal recurring adjustments, necessary for a fair presentation of this data for those dates. You should read this information in conjunction with Independence Bank's audited financial statements and related notes for the years ended December 31, 2013 and 2012 and Independence Bank's unaudited financial statements and related notes for the nine months ended September 30, 2014 and 2013, which are included in this document and from which this information is derived.