8-K

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT
PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934

Date of Report (Date of earliest
event reported) March 1, 2015

PacWest Bancorp

(Exact name of registrant as specified in its charter)

Delaware	00-30747	33-0885320
(State of	(Commission File Number)	(IRS Employer
Incorporation)		Identification No.)

10250 Constellation Blvd., Suite 1640, Los Angeles, California 90067

(Address of principal executive offices and zip code)

(310) 286-1144

(Registrant’s telephone number, including area code)

N/A

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

x Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230-425)

o Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

o Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

o Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 8.01 Other Events.

On March 2, 2015, PacWest Bancorp (“PacWest”) and Square 1 Financial, Inc. (“Square 1”) issued a joint press release announcing the execution of an Agreement and Plan of Merger, dated as of March 1, 2015, by and between PacWest and Square 1, pursuant to which PacWest and Square 1 will merge, subject to the terms and conditions set forth therein.  A copy of the press release is attached hereto as Exhibit 99.1 and is incorporated herein by reference.  In addition, PacWest and Square 1 intend to make available to investors on PacWest’s website the slides attached hereto as Exhibit 99.2, which are incorporated herein by reference.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits.

Exhibit
No.	Description
99.1	Joint Press Release, dated March 2, 2015.
99.2	Investor Presentation, dated March 2, 2015.

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SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

PacWest Bancorp
By:	/s/ Kori L. Ogrosky
Name:	Kori L. Ogrosky
Title:	Executive Vice President, General Counsel & Corporate Secretary

Date:  March 2, 2015

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EXHIBIT INDEX

Exhibit No.	Description
99.1	Joint Press Release, dated March 2, 2015.
99.2	Investor Presentation, dated March 2, 2015.

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EX-99.1

Exhibit 99.1

PRESS RELEASE

PacWest Bancorp 10250 Constellation Blvd., Suite 1640 Los Angeles, CA 90067	Square 1 Financial, Inc. 406 Blackwell Street, Suite 240 Durham, NC 27701
Contacts: Matthew P. Wagner President and Chief Executive Officer (310) 728-1020	Contacts: Douglas H. Bowers President and Chief Executive Officer (919) 627-6339

FOR IMMEDIATE RELEASE March 2, 2015

PACWEST BANCORP AND SQUARE 1 FINANCIAL, INC. AGREE TO MERGE

—Transaction will create a $19.8 billion asset commercial bank —

— Square 1 stockholders will receive at closing PacWest common stock based on a fixed exchange ratio of 0.5997—

—Based on the PacWest pre-announcement closing common stock price, total consideration

for each Square 1 share would be $27.49—

—Transaction valued at approximately $849 million—

LOS ANGELES, CA, and DURHAM, NC, March 2, 2015. PacWest Bancorp (NASDAQ: PACW — “PacWest”) and Square 1 Financial, Inc. (NASDAQ: SQBK — “Square 1”) today announced the signing of a definitive agreement and plan of merger (the “Agreement”) whereby PacWest will acquire Square 1 in a transaction valued at approximately $849 million.  The Square 1 lending operations will continue to do business under the name Square 1 as a division of Pacific Western Bank.

Square 1 Financial, Inc., headquartered in Durham, North Carolina, is the parent of Square 1 Bank, a North Carolina commercial bank with approximately $3.1 billion in assets at December 31, 2014, one banking office in Durham, and twelve loan production offices throughout the United States.  In connection with the transaction, Square 1 Bank will be merged into Pacific Western Bank, the Los Angeles-based, wholly-owned subsidiary of PacWest Bancorp.  PacWest had $16.2 billion in assets at December 31, 2014 and 80 branches located primarily in southern and central California.  The combined company will remain headquartered in Los Angeles and will have senior executives from each of the organizations in key positions.  Upon completion of the transaction, one former Square 1 director will be appointed to the PacWest board.

The transaction, currently expected to close in the fourth quarter of 2015, is subject to customary conditions, including the approval of bank regulatory authorities and the Square 1 stockholders. Certain stockholders of Square 1 have agreed to vote in favor of the transaction.

As of December 31, 2014, on a pro forma consolidated basis, the combined company would have had approximately $19.8 billion in assets with 80 branches throughout California and one in North Carolina.  The combined institution would be the 6th largest publicly-owned bank headquartered in California.

Under the terms of the Agreement, Square 1 stockholders will receive 0.5997 shares of PacWest common stock for each share of Square 1 common stock. The total value of the per share merger consideration, based on the closing price of PacWest common stock on February 27, 2015, of $45.84 is $27.49.

The transaction is intended to qualify as a tax-free reorganization for U.S. federal income tax purposes and Square 1 stockholders are not expected to recognize gain or loss to the extent of the stock consideration received.

Matt Wagner, CEO of PacWest Bancorp, commented, “We are very excited to align ourselves with the Square 1 team. Thanks to the talented professionals and founders that built this successful institution, we are confident this transaction with Square 1 represents an excellent opportunity to grow core deposits, expand our nationwide lending platform, and increase our presence in the dynamic technology and life-sciences markets.”

“Joining PacWest will be a terrific opportunity for our clients, employees, and stockholders,” said Doug Bowers, CEO of Square 1.  “Square 1 offers PacWest a complementary line of business and significant core deposit growth.  As part of PacWest, we will maintain our steadfast commitment to the entrepreneurial and venture communities, will be able to offer clients a wider array of products and will be well-positioned to continue to serve them through all stages of their growth.”

In connection with the announcement of the transaction, an investor presentation will be filed with the SEC and is available on the websites of both PacWest Bancorp and Square 1.  On the PacWest Bancorp website, the presentation can be found under the link for “Presentations”.  On the Square 1 website, the presentation can be found under the link for “Events & Presentations”.

Sandler O’Neill acted as financial advisor to Square 1 in the transaction and delivered a fairness opinion to the Board of Directors of Square 1. Wachtell, Lipton, Rosen & Katz served as legal counsel to Square 1.  Jefferies LLC acted as financial advisor to PacWest.  Sullivan & Cromwell LLP served as legal counsel to PacWest.

ABOUT PACWEST BANCORP

PacWest Bancorp (“PacWest”) is a bank holding company with over $16 billion in assets as of December 31, 2014, with one wholly-owned banking subsidiary, Pacific Western Bank (“Pacific Western”). Through 80 full-service branches located throughout the state of California, Pacific Western provides commercial banking services, including real estate, construction, and commercial loans, to small and medium-sized businesses. Through its CapitalSource division it delivers a full spectrum of financing solutions nationwide across numerous industries and property types. Pacific Western Bank has key lending offices located in Chevy Chase, Maryland, Southern California, including Los Angeles, St. Louis, Missouri, Denver, Colorado, Chicago, Illinois, New York, New York, and Midvale, Utah. Pacific Western Bank also maintains a number of smaller lending offices throughout the country. For more information about PacWest Bancorp, visit www.pacwestbancorp.com, or to learn more about Pacific Western Bank, visit www.pacificwesternbank.com.

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ABOUT SQUARE 1 FINANCIAL, INC.

Square 1 is a financial services company focused primarily on serving entrepreneurs and their investors. Square 1 (Nasdaq:SQBK) is headquartered in Durham, North Carolina with twelve loan production offices located in key innovation hubs across the United States. Through Square 1 Bank, which was formed by experienced venture bankers, commercial bankers and entrepreneurs, Square 1 offers a full range of banking and financial products focused on the entrepreneurial community and their venture capital and private equity investors. Since inception, Square 1 has operated as a highly-focused venture bank and has provided a broad range of financial services to entrepreneurs, growing entrepreneurial companies and the venture capital and private equity communities. Square 1 provides banking services to its clients, including venture, commercial and international banking services, asset-based lending programs, and SBA and USDA commercial and real estate loan programs.  Square 1 also provides investment advisory and asset management services to its clients through Square 1 Asset Management, a subsidiary of Square 1 Bank.  More information can be found at www.square1financial.com.

FORWARD-LOOKING STATEMENTS

This communication contains certain forward-looking information about PacWest, Square 1, and the combined company after the close of the transaction that is intended to be covered by the safe harbor for “forward-looking statements” provided by the Private Securities Litigation Reform Act of 1995. All statements other than statements of historical fact are forward-looking statements. Such statements involve inherent risks and uncertainties, many of which are difficult to predict and are generally beyond the control of PacWest, Square 1 and the combined company. Forward-looking statements speak only as of the date they are made and we assume no duty to update such statements. We caution readers that a number of important factors could cause actual results to differ materially from those expressed in, or implied or projected by, such forward-looking statements. In addition to factors previously disclosed in reports filed by PacWest and Square 1 with the SEC, risks and uncertainties for each institution and the combined institution include, but are not limited to: lower than expected revenues; credit quality deterioration or a reduction in real estate values could cause an increase in the allowance for credit losses and a reduction in net earnings; increased competitive pressure among depository institutions; the ability to complete the proposed transaction, including obtaining regulatory approvals and approval by the stockholders of Square 1, or any future transaction, successfully integrate such acquired entities, or achieve expected beneficial synergies and/or operating efficiencies, in each case within expected time-frames or at all; regulatory approvals may not be received on expected timeframes or at all; the possibility that personnel changes will not proceed as planned; the possibility that the cost of additional capital may be more than expected; the possibility that a change in the interest rate environment may reduce net interest margins; asset/liability re-pricing risks and liquidity risks; pending legal matters may take longer or cost more to resolve or may be resolved adversely; general economic conditions, either nationally or in the market areas in which the entities operate or anticipate doing business, are less favorable than expected; and environmental conditions, including natural disasters, may disrupt business, impede operations, or negatively impact the values of collateral securing loans.

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ADDITIONAL INFORMATION ABOUT THE PROPOSED TRANSACTION AND WHERE TO FIND IT

Investors and security holders are urged to carefully review and consider each of PacWest Bancorp’s and Square 1’s public filings with the SEC, including but not limited to their Annual Reports on Form 10-K, their proxy statements, their Current Reports on Form 8-K and their Quarterly Reports on Form 10-Q.  The documents filed by PacWest with the SEC may be obtained free of charge at PacWest’s website at www.pacwestbancorp.com or at the SEC’s website at www.sec.gov. These documents may also be obtained free of charge from PacWest by requesting them in writing to PacWest Bancorp, c/o Pacific Western Bank, 130 S. State College Blvd., Brea, CA 92821, Attention: Investor Relations, telephone (714) 671-6800, or via e-mail to investor-relations@pacwestbancorp.com.

The documents filed by Square 1 with the SEC may be obtained free of charge at Square 1’s website at www.square1bank.com or at the SEC’s website at www.sec.gov. These documents may also be obtained free of charge from Square 1 by requesting them in writing to Square 1 Financial, c/o Square 1 Bank, 406 Blackwell Street, Suite 240, Durham, NC 27701; Attention: Investor Relations, or by telephone at Phone: (866) 355-0468.

PacWest intends to file a registration statement with the SEC which will include a proxy statement of Square 1 and a prospectus of PacWest, and each party will file other documents regarding the proposed transaction with the SEC.  Before making any voting or investment decision, investors and security holders of Square 1 are urged to carefully read the entire registration statement and proxy statement/prospectus, when they become available, as well as any amendments or supplements to these documents, because they will contain important information about the proposed transaction. A definitive proxy statement/prospectus will be sent to the stockholders of Square 1 seeking any required stockholder approvals. Investors and security holders will be able to obtain the registration statement and the proxy statement/prospectus free of charge from the SEC’s website or from PacWest or Square 1 by writing to the addresses provided for each company set forth in the paragraphs above.

PacWest, Square 1, their directors, executive officers and certain other persons may be deemed to be participants in the solicitation of proxies from Square 1 stockholders in favor of the approval of the transaction.  Information about the directors and executive officers of PacWest and their ownership of PacWest common stock is set forth in the proxy statement for PacWest’s 2014 annual meeting of stockholders, as previously filed with the SEC.  Information about the directors and executive officers of Square 1 and their ownership of Square 1 common stock is set forth in the proxy statement for Square 1’s 2014 annual meeting of stockholders, as previously filed with the SEC.  Stockholders may obtain additional information regarding the interests of such participants by reading the registration statement and the proxy statement/prospectus when they become available.

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EX-99.2

Exhibit 99.2

ACQUISITION OF SQUARE 1 FINANCIAL March 2, 2015

 This communication contains certain forward-looking information about PacWest, Square 1, and the combined company after the close of the transaction that is intended to be covered by the safe harbor for “forward-looking statements” provided by the Private Securities Litigation Reform Act of 1995. All statements other than statements of historical fact are forward-looking statements. Such statements involve inherent risks and uncertainties, many of which are difficult to predict and are generally beyond the control of PacWest, Square 1 and the combined company. Forward-looking statements speak only as of the date they are made and we assume no duty to update such statements. We caution readers that a number of important factors could cause actual results to differ materially from those expressed in, or implied or projected by, such forward-looking statements. In addition to factors previously disclosed in reports filed by PacWest and Square 1 with the SEC, risks and uncertainties for each institution and the combined institution include, but are not limited to: lower than expected revenues; credit quality deterioration or a reduction in real estate values could cause an increase in the allowance for credit losses and a reduction in net earnings; increased competitive pressure among depository institutions; the ability to complete the proposed transaction, including obtaining regulatory approvals and approval by the stockholders of Square 1, or any future transaction, successfully integrate such acquired entities, or achieve expected beneficial synergies and/or operating efficiencies, in each case within expected time-frames or at all; regulatory approvals may not be received on expected timeframes or at all; the possibility that personnel changes will not proceed as planned; the possibility that the cost of additional capital may be more than expected; the possibility that a change in the interest rate environment may reduce net interest margins; asset/liability re-pricing risks and liquidity risks; pending legal matters may take longer or cost more to resolve or may be resolved adversely; general economic conditions, either nationally or in the market areas in which the entities operate or anticipate doing business, are less favorable than expected; and environmental conditions, including natural disasters, may disrupt business, impede operations, or negatively impact the values of collateral securing loans. Pro forma, projected and estimated numbers are used for illustrative purposes only and are not forecasts, and actual results may differ materially. Forward-Looking Statements

Summary of Transaction Highly Valued Business Model: California commercial bank Proven track record of generating core deposits National lending platform Robust loan and lease generation engine Outstanding track record of performance Experienced acquiror Current Priorities: Replace CDs from CapitalSource acquisition with core deposits Add highly-valued business lines Continue earnings growth and industry leading returns Highly Valued Business Model: Commercial bank focusing on technology with entrepreneurs nationwide Outstanding core deposit base High growth loan portfolio Success since launch in 2005 Meets PacWest Priorities: Accelerates replacement of CapitalSource CDs with core deposits New high-margin nationwide commercial business line Supports continued earnings growth through balance sheet improvement

Transaction Metrics Per Share Price: $27.49 per share Transaction Value: $849 million in aggregate Consideration Mix: 100% PacWest Common Stock Cash for outstanding options, warrants, RSUs Fixed Exchange Ratio: 0.5997x Assumed Closing: 4Q15 Transaction Summary Capital Ratios at Close TCE / TA ratio of 11.5% Price / 2015E EPS(1): 22.0x Price / Tangible Book Value: 2.63x Core Deposit Premium(2): 14.2% Transaction Valuation 2016E EPS Impact(1): < 1% Dilutive 2017E EPS Impact(1): 0% Pro Forma TBV / Share Dilution at Close(3): < 2% IRR(4): > 15.0% PACW Financial Impact Note: Market data as of February 27, 2015 Estimated financial impact is presented solely for illustrative purposes using IBES consensus estimates. Neither PacWest nor Square 1 endorse the IBES estimates or publish financial guidance. Actual results may differ materially Core deposits are defined as total deposits (including an estimated $1.1bn Client Investment Funds moving on balance sheet) less time deposits Includes restructuring charges Assumes a 9.0% TCE / TA threshold and 15.0x forward P/E exit multiple

Additional Information Cost savings equal to 20% of Square 1 operating expense base ($13.9mm pre-tax) realized in 2016 Pre-tax restructuring charge and transaction costs equal to $33.0mm ($21.9mm after-tax) Cost Savings / Restructuring Charge Other Assumed closing in 4Q15 40% tax rate Approximately $1.1bn of Square 1’s $1.4bn Client Investment Funds (“CIF”) pool used to replace PACW time deposits Savings of ~50 basis points pre-tax on CIF used to replace time deposits Funding Synergies $17 million loan write-down(1) (includes $8mm accretable discount over 4-year life) $6mm securities write-up (premium amortized over 2-year life) CDI equal to $18mm (amortized over 7-year life) Fair Value Marks - Net Earnings Impact Comprised of $23mm credit mark (existing ALLL) offset by $6mm premium for interest rate mark

Transaction Rationale Reduced reliance on higher-cost CDs Enhanced balance sheet liquidity ratios Better positioned for rising rates Improves Deposit and Liquidity Position Seasoned management team with an extensive network and a proven track record Bankers adding valuable industry experience within niche banking areas are expected to remain with the combined company Enhances Loan Growth and Product Diversification Preserves Senior Management within Business Lines Strong historical loan growth Supplements existing specialty lending practices with focus on venture-backed technology and science companies Loan portfolio diversified across industry, stage, geography and size Contributes additional sources of fee income Attractive returns (ROAA, ROATCE) at levels above peers are expected to continue All stock transaction preserves capital ratios with minimal impact High growth loan portfolio with track record of strong performance through and after the financial crisis Compelling Financial Metrics

Seattle, WA Menlo Park, CA San Diego, CA Los Angeles, CA Denver, CO Austin, TX Durham, NC (headquarters and single registered branch) Chevy Chase, MD New York, NY Waltham, MA San Francisco, CA Orange County, CA Campbell, CA Square 1 Financial Franchise Overview & Office Locations $3.1 billion bank holding company Founded in 2005 by veteran venture bankers with expertise in lending to venture-backed companies and their investors Based in Durham, NC with 13 offices located in key innovation markets Company / History Target customers are venture-backed technology and life sciences companies Deploy low cost deposits primarily to fund loans to venture-backed companies from their first investments through post-IPO or acquisition, and cross-sell other banking services Provide loans, deposits, treasury management services and investment advisory services catering to the venture capital community Business / Services

Square 1 Loan and Deposit Growth Loan Growth Organic growth across all business lines Growth in loans tied to deeper coverage in key markets and increase in brand awareness Funded by continued success in growing low cost deposits Compound Annual Loan Growth Rate of 29% since 2010 Deposit Growth Growth in deposits is tied to growth in client base and strong venture capital funding environment Average annual deposit growth of 19% since 2011 Compound Annual Deposit Growth Rate (including Client Investment Funds) of 25% since 2010 CAGR: 29% CAGR (including Client Investment Funds): 25%

Square 1 Operating Metrics Source: SNL Financial and company filings (1) Adjusted ROAA excludes realized loss on securities 7.02 6.94 6.77 6.34 6.32 4.22 4.02 4.14 3.91 4.06 2010Y 2011Y 2012Y 2013Y 2014Y Loan Yield (%) NIM (%) 0.11 0.06 0.03 0.04 0.02 2010Y 2011Y 2012Y 2013Y 2014Y Deposit COF (%) 0.42 0.68 0.84 1.06 1.25 2010Y 2011Y 2012Y 2013Y 2014Y Adj ROAA (%) (1)

Pro Forma Loan and Deposit Composition Source: Company filings (1) Includes $1.1 billion of Client Investment Funds moving on balance sheet as MMDA deposits (1) (1) Total Deposits = $15.6 bn PACW Square 1 Pro Forma Gross Loans = $11.9 bn Gross Loans = $1.3 bn Gross Loans = $13.2 bn Total Deposits = $11.8 bn Total Deposits & CIF = $4.2 bn Technology, 7% Healthcare, 5% SBA, 4% Lender Finance , 12% Consumer, 1% Construction 3% Comm. RE, 26% Multifamily, 7% Residential RE, 2% Healthcare RE, 9% Professional Practice, 1% Security, 3% General Cash Flow, 5% Other ABL, 6% Healthcare ABL, 1% Equip Finance, 8% Technology, 47% Life Sciences, 21% SBA & USDA, 3% Other Comm., 1% Construction <1% Real Estate, 3% Asset Based, 13% VC / PE, 13% Technology, 11% Life Sciences, 2% SBA RE, 3% Other C&I, 40% Consumer & Other, 1% Construction ,2% Comm. RE, 23% Multifamily RE, 6% Residential RE, 2% Healthcare RE, 8% VC / PE, 1% Savings, 6% MMDA, 15% Interest Checking, 6% Brokered Deposits, 1% Non. Int. Bearing, 25% Time Deposits, 47% MMDA, 20% Interest Checking, 2% Non. Int. Bearing, 44% Time Deposits, <1% Client Investment Funds, 34% Savings, 5% MMDA, 23% Interest Checking, 5% Brokered Deposits, 1% Non. Int. Bearing, 31% Time Deposits, 35%

Pro Forma Capital Ratios Capital ratios are based on applying the 2015 Basel III phase in rules Pro Forma PacWest With Consolidated Capital Ratios Standalone Square 1 Tier 1 Common Equity Ratio 12.3% 12.6% Tier 1 Risk-Based Capital Ratio 12.3% 12.6% Total Risk-Based Capital Ratio 15.9% 15.7% Tier 1 Leverage Ratio 11.9% 11.1% Tangible Common Equity Ratio 12.2% 11.5% At December 31, 2014

Conclusion Adds a highly liquid balance sheet with a very low all-in cost of funds at 2 bps Additional $1.4 billion pool of low-cost deposits available from Client Investment Funds Diversifies PACW’s nationwide lending platform across high growth venture capital and life science business lines Portfolio with 29% compound annual growth since 2010 Established track record of strong asset quality SQBK has an attractive profitability profile (1.25% 2014 ROAA) with ability for improved returns in a rising rate environment Variable rate loans comprise 92% of Square 1’s loan portfolio Non-interest bearing deposits represent 67% of total on-balance sheet deposits Enhances PACW franchise through a team of seasoned bankers with extensive expertise in lending to venture backed companies

Appendix – 12/31/2014 Pro Forma Balance Sheet $6mm write-up of securities. $23mm loan credit mark and $6mm loan rate write-up. Elimination of Square 1’s loan loss reserves. Reduction of deferred tax liability related to mark-to-market adjustments. $41K time deposit write-down. $36mm cash out of equity awards and $22mm after-tax restructuring charge. Elimination of Square 1’s intangibles. Elimination of Square 1’s equity and $22mm after-tax restructuring charge. $7mm deferred tax asset reduction related to core deposit intangible. $5mm deferred tax asset increase related to tax credit adjustment for RSU expense. Core deposit intangible. $813mm equity issued and $5mm tax credit adjustment for RSU expense. Standalone 12/31/14 Adjusted Purchase Accounting Pro PacWest Square 1 MTM Square 1 Eliminations Additions Forma Assets: Cash and Securities $1,921.0 $1,683.1 $6.0 $1,689.1 ($57.9) $0.0 $3,552.2 Gross Loans 11,882.4 1,346.4 (16.8) 1,329.6 0.0 0.0 13,212.1 Loan Loss Reserve (84.5) (22.9) 22.9 0.0 0.0 0.0 (84.5) Net Loans 11,798.0 1,323.5 6.1 1,329.6 0.0 0.0 13,127.6 Other Tangible Assets 778.1 87.8 (4.9) 82.9 0.0 (2.4) 858.7 Total Tangible Assets 14,497.1 3,094.5 7.2 3,101.7 (57.9) (2.4) 17,538.5 Goodwill 1,720.5 0.0 0.0 0.0 0.0 528.6 2,249.1 Other Intangibles 17.2 0.4 0.0 0.4 (0.4) 18.0 35.2 Intangible Assets 1,737.7 0.4 0.0 0.4 (0.4) 546.6 2,284.3 Assets $16,234.8 $3,094.9 $7.2 $3,102.1 ($58.3) $544.2 $19,822.8 Liabilities & Shareholders' Equity: Deposits $11,755.1 $2,776.6 ($0.0) $2,776.5 $0.0 $0.0 $14,531.6 Borrowings 817.0 0.0 0.0 0.0 0.0 0.0 817.0 Other Liabilities 156.3 15.6 0.0 15.6 0.0 0.0 171.9 Liabilities and Borrowings 12,728.4 2,792.2 (0.0) 2,792.1 0.0 0.0 15,520.5 Common Equity 3,506.4 302.7 7.3 310.0 (331.9) 817.8 4,302.3 Liabilities & Shareholders' Equity $16,234.8 $3,094.9 $7.2 $3,102.1 ($331.9) $817.8 $19,822.8 (1) (2) (4) (3) (5) (6) (7) (8) (9) (10) (11)

Investors and security holders are urged to carefully review and consider each of PacWest Bancorp’s and Square 1’s public filings with the SEC, including but not limited to their Annual Reports on Form 10-K, their proxy statements, their Current Reports on Form 8-K and their Quarterly Reports on Form 10-Q. The documents filed by PacWest with the SEC may be obtained free of charge at PacWest’s website at www.pacwestbancorp.com or at the SEC’s website at www.sec.gov. These documents may also be obtained free of charge from PacWest by requesting them in writing to PacWest Bancorp, c/o Pacific Western Bank, 130 S. State College Boulevard, Brea, CA 92821; Attention: Investor Relations, by telephone at (714) 671-6800 or via e-mail to investor-relations@pacwestbancorp.com. The documents filed by Square 1 with the SEC may be obtained free of charge at Square 1’s website at www.square1bank.com or at the SEC’s website at www.sec.gov. These documents may also be obtained free of charge from Square 1 by requesting them in writing to Square 1 Financial, c/o Square 1 Bank, 406 Blackwell Street, Suite 240, Durham, NC 27701; Attention: Investor Relations, or by telephone at Phone: (866) 355-0468. PacWest intends to file a registration statement with the SEC which will include a proxy statement of Square 1 and a prospectus of PacWest, and each party will file other documents regarding the proposed transaction with the SEC. Before making any voting or investment decision, investors and security holders of Square 1 are urged to carefully read the entire registration statement and proxy statement/prospectus, when they become available, as well as any amendments or supplements to these documents, because they will contain important information about the proposed transaction. A definitive proxy statement/prospectus will be sent to the stockholders of Square 1 seeking any required stockholder approvals. Investors and security holders will be able to obtain the registration statement and the proxy statement/prospectus free of charge from the SEC’s website or from PacWest or Square 1 by writing to the addresses provided for each company set forth in the paragraphs above. PacWest, Square 1, their directors, executive officers and certain other persons may be deemed to be participants in the solicitation of proxies from Square 1 stockholders in favor of the approval of the transaction. Information about the directors and executive officers of PacWest and their ownership of PacWest common stock is set forth in the proxy statement for PacWest’s 2014 annual meeting of stockholders, as previously filed with the SEC. Information about the directors and executive officers of Square 1 and their ownership of Square 1 common stock is set forth in the proxy statement for Square 1’s 2014 annual meeting of stockholders, as previously filed with the SEC. Stockholders may obtain additional information regarding the interests of such participants by reading the registration statement and the proxy statement/prospectus when they become available. Additional Information About the Transaction and Where to Find It