Pacwest Bancorp (PACW) 8-K 2017 Fourth Quarter Results Investor Presentation

Exhibit 99.1

2017 Fourth Quarter Results Investor Presentation

This communication contains certain “forward-looking statements” about PacWest Bancorp (the “Company”) and its subsidiaries within the meaning of the Private Securities Litigation Reform Act of 1995, including certain plans, strategies, goals, and projections and including statements about our expectations regarding our allowance for loan and lease losses, credit trends, deposit growth, profitability, capital management, including reducing excess capital, interest rate risk ,estimated impacts of the Tax Cuts and Jobs Act and operating expenses. All statements contained in this communication that are not clearly historical in nature are forward-looking, and the words “anticipate,” “assume,” “intend,” “believe,” “forecast,” “expect,” “estimate,” “plan,” “continue,” “will,” “should,” “look forward” and similar expressions are generally intended to identify forward-looking statements. All forward-looking statements (including statements regarding future financial and operating results and future transactions and their results) involve risks, uncertainties and contingencies, many of which are beyond our control, which may cause actual results, performance, or achievements to differ materially from anticipated results, performance or achievements. Actual results could differ materially from those contained or implied by such forward-looking statements for a variety of factors, including without limitation: higher than anticipated delinquencies, charge-offs and loan and lease losses; reduced demand for our services due to strategic or regulatory reasons; changes in economic or competitive market conditions could negatively impact investment or lending opportunities or product pricing and services; credit quality deterioration or pronounced and sustained reduction in market values or other economic factors which adversely affect our borrowers’ ability to repay loans and leases and/or require an increased provision for loan and lease losses; compression of the net interest margin due to changes in our interest rate environment, loan products, spreads on newly originated loans and leases and/or asset mix; the impact of asset/liability repricing risk and liquidity risk on net interest margin and the value of investments; higher than anticipated increases in operating expenses; increased costs to manage and sell foreclosed assets; the need to retain capital for strategic or regulatory reasons; the financial performance of the Company; increased litigation; increased asset workout or loan servicing expenses; higher compensation costs and professional fees to retain and/or incent employees; our ability to complete future acquisitions and to successfully integrate such acquired entities or achieve expected benefits, synergies and/or operating efficiencies within expected timeframes or at all; the impact of the Dodd-Frank Wall Street Reform and Consumer Protection Act on our business and business strategies; and other risk factors described in documents filed by the Company with the U.S. Securities and Exchange Commission (“SEC”). All forward-looking statements included in this communication are based on information available at the time of the communication. Pro forma, projected and estimated numbers are used for illustrative purposes only and are not forecasts, and actual results may differ materially. We are under no obligation to (and expressly disclaim any such obligation to) update or alter our forward-looking statements, whether as a result of new information, future events or otherwise except as required by law. Forward-Looking Statements

Company Overview 4 Fourth Quarter Highlights 8 Investment Securities 15 Loans and Leases 17 Credit Quality 26 Deposits 30 Net Interest Margin 33 Controlled Expenses 38 Acquisitions 41 Strong Franchise Value 45 Non-GAAP Measurements 48 Presentation Index

Company Overview

We are a commercial bank focused on core deposit growth paired with national lending and venture banking platforms NASDAQ traded (PACW) with a market capitalization of $6.9 billion (1) Average daily trading volume of 978,738 shares over the last three months (1) Dividend: $2.00 per share, 3.77% yield (1) 5th largest publicly-traded bank headquartered in California with total assets of $25.0 billion, loans and leases of $17.0 billion and deposits of $18.9 billion at December 31, 2017 Profitable Growth Net earnings of $357.8 million, return on average assets (“ROAA”) of 1.58% and return on average tangible equity (“ROATE”) of 15.15% for FY2017 Industry leading tax equivalent NIM of 5.10% for FY2017 Loan and lease production of $1.6 billion in 4Q17 ($4.7 billion FY2017) $15.9 billion of core deposits with cost of average total deposits of 30 basis points for 4Q17 NPAs at 0.93% of total loans and leases and foreclosed assets Efficiency ratio of 41.0 % in 4Q17 (40.8% FY2017) Experienced acquirer with 29 bank and finance company acquisitions since 2000 CU Bancorp (“CUB”) acquisition closed on October 20, 2017. CUB added approximately $2.1 billion in loans and $2.7 billion in deposits. Analyst coverage: BMO Capital Markets, D.A. Davidson & Co., FIG Partners, B. Riley FBR, JMP Securities, Keefe, Bruyette & Woods, Piper Jaffray, Raymond James, Sandler O’Neill & Partners, Stephens Inc., SunTrust Robinson Humphrey, Wedbush Morgan, Wells Fargo Securities (1) As of January 24, 2018 Company Overview

Business Model Community Banking National Lending Venture Banking Pacific Western Bank Attractive branch network with 74 full service branches in California(1) Offers a full suite of deposit products and services, including on-line banking Focused on business lending products, including commercial real estate Limited consumer loan offerings Borrower relationships generally include a deposit account Efficient deposit model with average branch size of $169 million Diversified by loan and lease type, geography and industry Asset-Based Lending (ABL) Lender Finance & Timeshare, Equipment Financing, Healthcare & General ABL Security Cash Flow Lending Commercial Real Estate General, Multifamily, SBA, Healthcare and Construction Focus on small to middle market businesses Expertise in niche segments limits new competitors Borrower relationships may include deposit accounts and treasury services Five banking groups: Technology, Life Sciences, Equity Funds Group, Structured Finance, Specialty Finance Operates a single branch in Durham, NC with $6.1 billion in deposits Offices located in key innovative hubs across the United States Offers a comprehensive suite of financial services for venture-backed companies and their venture capital and private equity investors Provides comprehensive treasury management solutions, including credit cards and international-related products and services to clients Borrower relationships almost always include a deposit account Operates Square 1 Asset Management (registered investment advisor) (1) Reflects planned 2018 consolidation of two branches in connection with CUB merger.

Source: SNL Financial and FactSet Research Systems; Market data as of 12/31/2017. Note: KBW Regional Bank Index (KRX) includes 50 institutions with a median market cap of $4.3 billion as of 12/31/2017; median weighted by market capitalization. Five Year Total Return

Fourth Quarter Highlights

See “Non-GAAP Measurements” slides beginning on page 48. Fourth Quarter Highlights Robust Earnings Net earnings of $84.0 million EPS of $0.66 ROAA and ROATE of 1.34% and 13.75% (1) Q4 includes $16.1 million of acquisition and integration costs related to CUB acquisition Industry Leading Net Interest Margin Tax equivalent NIM of 4.97% Yield on average loans and leases of 5.89% Low Efficiency Ratio Efficiency ratio of 41.0% Average branch size of $245 million in deposits Noninterest expense to average assets of 2.29% Profitable Deposit Base Cost of average total deposits of 30 bps $2.4 billion net core deposit growth, primarily from CUB acquisition Core deposits now represent 85% of total deposits Loan and Lease Production and Credit Quality Loan and lease production of $1.6 billion Organic loan and lease growth of 17% annualized NPAs to total loans and leases and foreclosed assets, excluding PCI loans, of 0.93% compared to 1.08% at September 30, 2017 Classified loans and leases to total loans and leases of 1.64% compared to 2.20% at September 30, 2017 Strong Capital Levels Tangible common equity ratio of 10.50% (1) CET1 and total capital ratios of 10.91% and 13.75% Tangible book value per share of $18.24 (1) Repurchased 2,081,227 shares in Q4 at an average cost of $47.89

See “Non-GAAP Measurements” slides beginning on page 48. . Financial Highlights ? ($ in millions, except per share amounts) 4Q17 3Q17 Q / Q Total Assets 24,995 $ 22,243 $ 12% Loans and Leases Held for Investment, net of deferred fees 16,973 $ 15,691 $ 8% Total Deposits 18,866 $ 16,773 $ 12% Core Deposits 15,937 $ 13,531 $ 18% Net Earnings 84.0 $ 101.5 $ -17% Earnings Per Share 0.66 $ 0.84 $ -21% Return on Average Assets 1.34% 1.82% -0.48 Return on Average Tangible Equity (1) 13.75% 16.85% -3.10 Tangible Common Equity Ratio (1) 10.50% 12.02% -1.52 Tangible Book Value Per Share (1) 18.24 $ 19.84 $ -8% Tax Equivalent Net Interest Margin 4.97% 5.08% -0.11 Efficiency Ratio 41.0% 40.4% 0.6%

Solid Earnings Track Record ($ in millions, except EPS) 1Q16 2Q16 3Q16 4Q16 1Q17 2Q17 3Q17 4Q17 Net Earnings 90.5 $ 82.2 $ 93.9 $ 85.6 $ 78.7 $ 93.6 $ 101.5 $ 84.0 $ Diluted EPS 0.74 $ 0.68 $ 0.77 $ 0.71 $ 0.65 $ 0.77 $ 0.84 $ 0.66 $ $0.40 $0.50 $0.60 $0.70 $0.80 $0.90 $1.00 $50 $60 $70 $80 $90 $100 $110 1Q16 2Q16 3Q16 4Q16 1Q17 2Q17 3Q17 4Q17 EPS Millions Net Earnings Diluted EPS

Source: SNL Financial using data as of 12/31/17 Solid Capital Position – 4Q17 12.21% 11.38% 11.87% 12.12% 12.19% 11.54% 11.67% 11.75% 12.02% 10.50% 8.72% 8.60% 8.78% 8.68% 8.92% 8.64% 8.80% 8.81% 8.87% 8.79% 3Q15 4Q15 1Q16 2Q16 3Q16 4Q16 1Q17 2Q17 3Q17 4Q17 TCE / TA PACW Median Banks $15-$25B 12.04% 11.67% 11.51% 11.92% 12.13% 11.91% 11.87% 11.90% 12.02% 10.66% 9.31% 9.23% 9.04% 9.16% 9.14% 9.28% 9.29% 9.33% 9.33% 9.55% 3Q15 4Q15 1Q16 2Q16 3Q16 4Q16 1Q17 2Q17 3Q17 4Q17 T1 Leverage PACW Median Banks $15-$25B 16.32% 15.65% 15.96% 16.08% 16.18% 15.56% 15.56% 15.56% 15.74% 13.75% 13.38% 13.16% 13.05% 13.05% 13.05% 13.22% 13.16% 13.34% 13.17% 13.20% 3Q15 4Q15 1Q16 2Q16 3Q16 4Q16 1Q17 2Q17 3Q17 4Q17 Total Capital PACW Median Banks $15-$25B 12.74% 12.58% 12.63% 12.72% 12.83% 12.31% 12.31% 12.28% 12.52% 10.91% 10.71% 10.65% 10.61% 10.50% 10.44% 10.90% 10.88% 11.00% 10.87% 10.74% 3Q15 4Q15 1Q16 2Q16 3Q16 4Q16 1Q17 2Q17 3Q17 4Q17 CET1 PACW Median Banks $15-$25B

4Q17 Loan Sales/Loans Held For Sale Deemphasized cash flow lending; in 4Q17 made decision to sell cash flow loans totaling $1.5 billion and exit the CapitalSource Division origination operations related to general, technology and healthcare cash flow loans. Approximately $1.0 billion sold and settled prior to year-end Approximately $481 million sold of which 99% settled as of January 29, 2018 No nonaccrual loans sold $4.7 million of sold loans were classified Retained general, technology and healthcare cash flow portfolio contains approximately $39 million of classified loans at December 31, 2017 Impact to 4Q17 results and financial statements $481.1 million classified as LHFS on balance sheet at December 31, 2017 Gain on sale of loans of $2.0 million and other related costs of $1.3 million recorded to noninterest income Gross charge-offs in 4Q include $2.2 million to record loans sold and LHFS at lower of cost or market (“LOCOM”) Decreased provision for loan losses of $14.1 million due in part to release of general reserves on loans transferred to LHFS in excess of LOCOM charge-offs Compensation expense of $2.9 million related to exiting certain lending operations $0.6 million noninterest expense charge related to sold unfunded commitments Increase in DTA valuation allowance of $2.0 million related to loans sold which generated foreign-sourced income utilized for foreign tax credits Healthcare Cash Flow, $411mm General Cash Flow, $356mm Technology Cash Flow, $705mm Loans Sold by Loan Type Total = $1.5 billion Healthcare, $29mm General, $20mm Technology, $200mm Retained General, Technology & Healthcare Cash Flow Loans Total = $249 million

Impacts in 4th quarter 2017: Net DTAs reduced from $65.3 million at 9/30/17 to a net DTL of $2.3 million at 12/31/17 driven by: Approximately $100 million of bonus tax depreciation for leased assets placed in service in Q4 which resulted in increased deferred tax liabilities of approximately $40 million Accelerated deduction of a portion of the 2017 bonuses deemed fixed and determinable (to be paid in 2018) which resulted in decreased deferred tax assets of approximately $15 million Re-measured federal deferred tax assets and liabilities at newly enacted federal tax rate of 21% which resulted in a $1.2 million tax benefit Sold approximately $173 million of securities to realize the loss of $3.3 million at the higher 35% tax rate; reinvested into higher yielding securities; recapture of loss expected in approximately one year Expected impacts going forward: Federal statutory corporate income tax rate reduced from 35% to 21% Allows for immediate capital expensing of certain qualified property Tax-equivalent net interest margin will be reduced by approximately 5 bps beginning in 2018 Performance based executive compensation now subject to $1 million deduction cap and definition of “covered person” expanded for senior executive officer compensation greater than $1 million Approximately 35% to 40% of our FDIC insurance assessments will no longer be deductible; deduction fully phased out at $50 billion in assets Analysis ongoing currently estimates that our 2018 effective tax rate will range from 27% to 29% Continue to analyze the new tax law and monitor guidance as issued Impacts of the Tax Cuts and Jobs Act

Investment Securities

3.20% overall portfolio tax equivalent yield (2) (1) Fair value (2) Yield is for 4Q17 Investment Portfolio Average Life and Effective Duration Municipal Securities Composition Diversified Investment Portfolio SBA Securities, $160.3mm, 4% Agency Residential MBS, $246.3mm, 7% Agency Residential CMOs, $275.7mm, 7% Agency Commercial MBS, $1,164.0mm, 31% Private CMOs, $126.0mm, 3% Municipal Securities, $1,680.1mm, 45% Other, $122.1mm, 3% $3.8 Billion Total Portfolio (1) S&P Ratings % Total Issue Type % Total AAA 12% G.O. Limited 6% AA 79% G.O. Unlimited 45% A 3% Revenue 49% Not rated 6% 100% 100% Municipal Securities 6.1 7.0 6.7 6.8 7.0 4.8 5.7 5.7 5.9 6.0 3 4 5 6 7 8 4Q16 1Q17 2Q17 3Q17 4Q17 Years Average Life Effective Duration

Loans and Leases

Diversified Loan and Lease Portfolio ($ in millions) $ Mix $ Mix Lender Finance & Timeshare 1,610 $ 9% 1,667 $ 11% Equipment Finance 657 4% 692 4% Healthcare Asset-Based 93 1% 181 1% Other Asset-Based 1,308 8% 764 5% Total Asset-Based 3,668 22% 3,304 21% Security Cash Flow 573 3% 440 3% Technology Cash Flow 200 2% 1,048 7% General and Other Cash Flow 183 1% 564 4% Healthcare Cash Flow 29 0% 799 5% Total Cash Flow 985 6% 2,851 19% Commercial Real Estate 3,990 24% 2,987 19% Income Producing Residential 2,245 13% 1,169 8% Construction and Land 1,591 9% 965 6% Healthcare Real Estate 844 5% 955 6% Small Business 552 3% 454 3% Owner-Occupied Residential 222 1% 145 1% Total Real Estate 9,444 55% 6,675 43% Venture Capital 2,123 13% 1,988 13% Other 753 4% 638 4% Total Loans HFI (1) 16,973 $ 100% 15,456 $ 100% (1) Net of deferred fees and costs 12/31/2017 12/31/2016 Lender Finance & Timeshare Equipment Finance Healthcare Asset - Based Other Asset - Based Security Cash Flow Technology Cash Flow General and Other Cash Flow Healthcare Cash Flow Commercial Real Estate Income Producing Residential Construction and Land Healthcare Real Estate Small Business Owner - Occupied Residential Venture Capital Other As of December 31, 2017

Diversified Loan and Lease Portfolio Healthcare, $844mm, 9% SBA, $552mm, 6% Hospitality, $722mm, 8% Retail, $568mm, 6% Multifamily, $2,085mm, 22% Office, $912mm, 10% Owner - occupied, $1,314mm, 14% Construction, $1,591mm, 16% Other, $856mm, 9% Real Estate ($9.4B) Technology, $200mm, 20% Healthcare, $29mm, 3% Security, $573mm, 58% General, $20mm, 2% Municipal, $67mm, 7% SBA, $96mm, 10% Cash Flow ($1.0B) Lender Finance & Timeshare, $1,610mm, 44% Equipment Finance, $657mm, 18% Healthcare, $93mm, 2% Other, $1,308mm, 36% Asset - Based ($3.7B) Later Stage, $255mm, 12% Expansion Stage, $953mm, 45% Equity Funds Group, $471mm, 22% Early Stage, $443mm, 21% Venture Capital ($2.1B)

Our CapitalSource Division has been an active, disciplined Healthcare CRE lender since 2001 From 2001 to 2017, the CapitalSource Division originated $5.1 billion of Healthcare CRE loans with total aggregate losses of $33.3 million (66 bps) 65% of our Healthcare CRE portfolio is secured by skilled nursing facilities (SNFs) Underwriting discipline includes: Lending at a conservative ratio of loan-to-value The facility-level underwritten projected “debt yield” (net operating income ÷ first lien debt) generally exceeds 15% Focus on experienced and reputable sponsors and operators On-staff licensed nursing home administrator to evaluate clinical compliance and quality of care Use of market per-bed or per-unit valuation trends and caps in conjunction with appraised values and underwritten values Analysis of payor mix and state and federal revenue sources to monitor cash flows Healthcare CRE Loans - $844 Million as of 4Q17 Non - classified, 92% Classified, 8% (3 loans) Total Healthcare CRE Portfolio By Risk Rating SNF, $549mm Assisted living, $144mm Continuing care, $65mm Hospital & Medical Office, $16mm Other, $70mm Total Healthcare CRE Portfolio By Property Type CA, $45mm PA, $86mm FL, $87mm NJ, $37mm VA, $71mm MN, $29mm NY, $27mm AZ, $31mm TX, $28mm Other, $108mm SNF Loans By State

Loan Types Construction- significant projects include: Redevelopment in Chicago’s exclusive Gold Coast luxury retail district A Walmart Supercenter-anchored shopping center in Inland Empire region of Southern California Development in a high density Brooklyn retail neighborhood that includes an Apple Store, Whole Foods, J. Crew, etc. High traffic retail infill on San Vicente Blvd. in Los Angeles Owner-Occupied Not adversely affected by rental market volatility SBA retail is 100% owner-occupied SBA guaranteed portions retained (75% avg. guarantee) CRE Traditional retail-focused commercial real estate lending including: CapitalSource Division $207mm portfolio of 10 loans across 7 states with $20.7mm average balance focused on lifestyle centers, urban luxury centers and grocery-anchored centers Community Bank Division $360mm portfolio almost entirely in California focused on suburban retail/strip centers and single tenant retail storefronts (1) $6.9 million classified at December 31, 2017 with related SBA guarantees totaling $1.9 million. Retail Real Estate Portfolio Overview Outstanding balance: $821mm (1) /4.8% of Loans

SNCs are not a line of business. SNC relationships are included in business line balances. SNCs are facilities greater than $20 million with a federally supervised agent/lead bank shared by three or more federally supervised financial institutions. At December 31st, approximately 55 SNC borrowers with $1.2 billion outstanding. Adhere to same credit underwriting standards as the rest of loan portfolio. No energy-related SNCs. At December 31st, $15 million (1.2%) on nonaccrual and $41 million (3.5%) classified. (1) Excludes loans held for sale at December 31, 2017 Shared National Credit (SNC) Relationships Management Consulting, $23mm, 1% Manufacturing, $117mm, 5% Other, $141mm, 7% Security, $257mm, 12% Technology, $577mm, 28% Transportation, $78mm, 4% Communications, $167mm, 8% Consumer Finance, $167mm, 8% Healthcare Cash Flow, $438mm, 21% Healthcare RE, $122mm, 6% $2.1B of Loans at 9/30/2017 Management Consulting, $0mm, 0% Manufacturing, $0mm, 0% Other, $243mm, 21% Security, $230mm, 19% Technology, $263mm, 22% Transportation, $43mm, 4% Communications, $0mm, 0% Consumer Finance, $207mm, 17% Healthcare Cash Flow, $83mm, 7% Healthcare RE, $121mm, 10% $1.2B of Loans at 12/31/2017 (1) Loan Sale + CUB

CapitalSource Credit Profile: Lessons Learned and Changes Implemented CapitalSource experienced elevated losses on loans originated between 2003 and 2008. 7.5% cumulative losses on $24 billion of originations, the substantial majority from lending products which were subsequently discontinued During 2008–09, a transformative de-risking effort was launched that included executive management changes, acquired an FDIC-insured bank subsidiary and made significant adjustments to lending practices. Management changes included the promotion of Jim Pieczynski to CEO in 2010 CapitalSource Bank adopted new bank-standard lending policies appropriate for an FDIC-insured institution Lending products that comprised nearly two-thirds of the aggregate losses were discontinued, including: Other lending product standards were adjusted: Limited general cash flow lending to selected industries and borrowers with strong market share, barriers to entry and support of proven equity sponsors Focused CRE lending on stabilized cash-flowing collateral Narrowed focus of Lender Finance group Added new lower-risk lending products, including SBA, multi-family and life insurance premium finance. Of the $24 billion originated from 2003 to 2008, approximately $342 million remains outstanding with $0.1 million classified as of December 31, 2017. (1) The CapitalSource Division reintroduced this product in 2015. CapitalSource Transition from Finance Company to Bank Subprime residential mortgage Media and retail cash flow loans Resort vacation club loans Second lien/mezzanine CRE Land loans Construction loans (other than SBA)(1) Eliminated Products, 33% Adjusted Products, 34% Unchanged Products, 33% 2003 - 2008 CapitalSource Division Originations ($24 Billion) Eliminated Products, 63% Adjusted Products, 33% Unchanged Products, 4% Cumulative Losses ($1.8 Billion)

Loan and Lease Production of $1.6 Billion in 4Q17 The weighted average rate on new production presents contractual rates and does not include amortized fees. Amortized fees added approximately 30 basis points to loan yields in 2017. $1,273 $1,049 $1,078 $1,003 $1,556 $765 $1,057 $700 $722 $724 $709 $1,213 $956 $903 $729 $582 $732 $587 $638 $813 $2,038 $2,106 $1,778 $1,725 $2,280 $1,291 $1,945 $1,543 $1,541 $1,542 4.0% 4.5% 5.0% 5.5% 6.0% $0 $500 $1,000 $1,500 $2,000 $2,500 Q4 Q1 Q2 Q3 Q4 2016 2017 Avg. Rate on Production Millions Production Disbursements Payoffs Paydowns Avg Production/Disbursement Avg Payoffs/Paydowns Rate on Production ($ in millions) Production/ Disbursement Payoffs/ Paydowns Net Change Rate on Production (1) 4Q17 2,280 $ 1,542 $ 738 $ 4.95% 3Q17 1,725 1,541 184 5.04% 2Q17 1,778 1,543 235 4.93% 1Q17 2,106 1,945 161 4.91% 4Q16 2,038 1,291 747 4.83%

Impact of Rising Rates on the Loan and Lease Portfolio (In Millions) Loan Rate Above Floor 1 to 25 Bps 26 to 100 Bps >100 Bps Total 1ML 5,489 1 59 - 5,549 3ML 287 - - - 287 Prime 3,601 133 27 99 3,860 Other 1,214 65 35 54 1,368 Total 10,591 199 121 153 11,064 Varaiable Loans Lift Off of Loan Floors Cumulative Amount of Loans Rate Increase Needed to Reprice ($ in millions) $10,911 1 to 100 bps $11,064 > 100 bps Repricing of Variable Rate Loans Amount % ($ in millions) 1-month LIBOR 5,597 $ 2-month LIBOR 46 3-month LIBOR 287 6-month LIBOR 1,600 12-month LIBOR 25 Total LIBOR-based Loans 7,555 56% Prime Rate 4,560 34% Other Index 1,302 10% Total Variable/Hybrid Loans 13,417 $ 100% Variable Rate and Hybrid Loans by Index $1,146 $827 $777 $3,217 1 Year 2 Years 3 Years > 3 Years Fixed/Hybrid Years to Maturity/Repricing ($ in Millions) Fixed Rate, 21% Variable Rate, 65% Hybrid, 14% Loan Portfolio by Repricing Type

Credit Quality

Classified loans and leases are those with a credit risk rating of substandard or doubtful Allowance for credit losses includes allowance for loan and lease losses and reserve for unfunded commitments Non-PCI Credit Quality ($ in thousands) 4Q17 3Q17 2Q17 1Q17 4Q16 Nonaccrual Loans and Leases HFI $ 155,784 157,697 172,576 173,030 170,599 As a % of Loans and Leases HFI % 0.92% 1.00% 1.11% 1.11% 1.11% Nonperforming Assets $ 157,113 169,327 185,854 185,872 183,575 As a % of Loans and Leases & Foreclosed Assets % 0.93% 1.08% 1.20% 1.20% 1.19% Classified Loans and Leases HFI (1) $ 278,405 344,777 339,977 424,399 409,645 As a % of Loans and Leases HFI % 1.64% 2.20% 2.19% 2.73% 2.66% Credit Loss Provision $ 6,500 15,500 12,500 24,500 21,000 As a % of Average Loans and Leases (annualized) % 0.15% 0.40% 0.33% 0.64% 0.56% Trailing Twelve Months Net Charge-offs $ 62,957 53,991 56,802 36,287 21,990 As a % of Average Loans and Leases % 0.40% 0.35% 0.37% 0.24% 0.15% Allowance for Credit Losses (ACL) (2) $ 161,647 173,579 159,142 167,589 161,278 As a % of Loans and Leases HFI % 0.95% 1.11% 1.02% 1.08% 1.05% ACL / Nonaccrual Loans and Leases HFI % 103.77% 110.08% 92.22% 96.86% 94.54%

Key Credit Trends – Non-PCI Loans HFI 1.05% 1.08% 1.02% 1.11% 0.95% 4Q16 1Q17 2Q17 3Q17 4Q17 ACL / Loans and Leases 2.66% 2.73% 2.19% 2.20% 1.64% 4Q16 1Q17 2Q17 3Q17 4Q17 Classified Loans and Leases / Average Loans and Leases 1.11% 1.11% 1.11% 1.00% 0.92% 4Q16 1Q17 2Q17 3Q17 4Q17 Nonaccrual Loans and Leases / Loans and Leases 1.19% 1.20% 1.20% 1.08% 0.93% 4Q16 1Q17 2Q17 3Q17 4Q17 NPAs / Loans and Leases and Foreclosed Assets

At December 31, 2017, the Company’s ten largest Non-PCI loan relationships on nonaccrual status had an aggregate book balance of $120 million and represented 77% of total Non-PCI nonaccrual loans and leases. Non-PCI Nonaccrual Loan and Lease Detail Excludes loans held for sale at lower of cost or fair value at December 31, 2017. The majority of the loans representing the increase in Non-PCI accruing 30-89 past due loans have subsequently been brought current, renewed or are subject to guarantees. % of Loan % of Loan 12/31/2017 9/30/2017 ($ in thousands) Balance Category Balance Category Balance Balance Real estate mortgage: Commercial 65,563 $ 1.2% 63,096 $ 1.5% 27,234 $ 1,446 $ Residential 3,350 0.1% 3,186 0.2% 6,629 282 Total real estate mortgage 68,913 0.9% 66,282 1.1% 33,863 1,728 Real estate construction and land: Commercial - 0.0% - 0.0% - - Residential - 0.0% - 0.0% 2,081 - Total R.E. construction and land - 0.0% - 0.0% 2,081 - Commercial: Cash flow 23,315 1.8% 33,514 1.2% 924 72 Equipment finance 30,938 4.7% 30,942 5.2% 1,512 - Venture capital 29,424 1.4% 22,686 1.2% 5,959 2,720 Asset-based 3,174 0.1% 3,977 0.2% 344 - Total commercial 86,851 1.2% 91,119 1.2% 8,739 2,792 Consumer 20 0.0% 296 0.1% 562 286 Total Loans HFI (1)(2) 155,784 $ 0.9% 157,697 $ 1.0% 45,245 $ 4,806 $ 12/31/2017 Nonaccrual Loans and Leases 9/30/2017 Accruing and 30 -89 Days Past Due

Deposits

Does not include $2.1 billion and $1.3 billion of client investment funds held at December 31, 2017 and December 31, 2016, respectively. Deposit Detail Core: 85% Core: 79% ($ in millions) Deposit Category Amount % of Total Amount % of Total Noninterest-bearing demand deposits 8,508 $ 45% 6,659 $ 42% Interest checking deposits 2,227 12% 1,448 9% Money market deposits 4,512 24% 3,706 23% Savings deposits 690 4% 711 5% Total core deposits 15,937 85% 12,524 79% Non-core non-maturity deposits 863 4% 1,175 7% Total non-maturity deposits 16,800 89% 13,699 86% Time deposits $250,000 and under 1,710 9% 1,758 11% Time deposits over $250,000 355 2% 414 3% Total time deposits 2,065 11% 2,172 14% Total deposits (1) 18,865 $ 100% 15,871 $ 100% December 31, 2017 December 31, 2016 Noninterest - bearing demand deposits Interest checking deposits Money market deposits Savings deposits Non - core non - maturity deposits Time deposits $250,000 and under Time deposits over $250,000 December 31, 2017 Noninterest - bearing demand deposits Interest checking deposits Money market deposits Savings deposits Non - core non - maturity deposits Time deposits $250,000 and under Time deposits over $250,000 December 31, 2016

Deposit Portfolio Includes brokered deposits of $682 million with a weighted average maturity of 4 months. $15.9 $16.3 $16.9 $16.8 $18.9 0.10% 0.20% 0.30% 0.40% 0.50% 0.60% 0.0 5.0 10.0 15.0 20.0 25.0 4Q16 1Q17 2Q17 3Q17 4Q17 Cost Balance ($ in Billions) Core Deposits Non-Core Deposits Cost of Interest-Bearing Deposits Cost of Total Deposits ($ in millions) Time Deposits Time Deposits Total $250,000 Over Time Time Deposit Maturities and Under $250,000 Deposits Due in three months or less 632 $ 182 $ 814 $ Due in over three months through six months 516 101 617 Due in over six months through twelve months 446 54 500 Due in over 12 months through 24 months 77 10 87 Due in over 24 months 39 8 47 Total 1,710 $ (1) 355 $ 2,065 $ December 31, 2017

Net Interest Margin

Includes 27bps in Q1 2016 and 29bps in Q4 2016 due to accelerated discount accretion from the payoff of nonaccrual PCI loans. Source: SNL Financial using data as of 1/26/18 (1) Industry Leading Tax Equivalent Net Interest Margin (1) (1)

Includes 34bps in Q1 2016 and 35bps in Q4 2016 due to accelerated discount accretion from the payoff of nonaccrual PCI loans. Source: SNL Financial using data as of 1/26/18 Higher Loan Yields From Disciplined & Diversified Lending (1) (1) (1)

Source: SNL Financial using data as of 1/26/18 Deposit Franchise: 4Q17 Deposit Cost of 30 Basis Points

Asset-Sensitive Balance Sheet Benefits From Rising Rates (1) The above table presents forecasted net interest income and net interest margin for the next 12 months using the forward yield curve as the base scenario and shocking the static balance sheet for immediate and sustained parallel upward movements in interest rates of 100, 200 and 300 basis points. ($ in millions) Forecasted Percentage Forecasted Net Interest Income Change Net Interest Margin Interest Rate Scenario (Tax Equivalent) From Base (Tax Equivalent) Up 300 basis points 1,208.3 $ 13.3% 5.63% Up 200 basis points 1,163.1 9.1% 5.42% Up 100 basis points 1,116.6 4.7% 5.20% Base case 1,066.3 - 4.97% December 31, 2017 0.0% 2.0% 4.0% 6.0% 8.0% 10.0% 12.0% 14.0% Base Up 100 Up 200 Up 300 PacWest Bancorp IRR Model Results - % Change in NII - Year 1 Static Balance Sheet - December 31, 2017 Sudden Parallel Shocks (1) PACW

Controlled Expenses

Source: SNL Financial using data as of 1/26/18 Efficiency Ratio Trend

Focus and Execution Drive Efficiency 55.0% 54.0% 56.4% 60.7% 41.6% 38.5% 39.8% 40.8% 2010 2011 2012 2013 2014 2015 2016 2017 Efficiency Ratio $57 $60 $70 $72 $147 $193 $203 $245 2010 2011 2012 2013 2014 2015 2016 2017 Average Branch Size ($ - M)

Acquisitions

Acquisition Strategy In-Market Consolidation Market Expansion Asset Generation Capability Strong Core Deposit Base Sound Strategic Focus Key Drivers of Accretion Cost Savings Customer Retention Margin Improvement

CU Bancorp – Transaction Summary 7 branches were consolidated in 4Q17 with an additional 2 branches to be consolidated in 1Q18 Leading C&I community bank in the LA metro area which will complement the PacWest franchise Growth opportunity for larger loans and deposits from existing customers A PacWest management team that is highly experienced in M&A, having completed 29 deals since inception System conversion completed in December 2017 Low risk transaction with significant efficiency opportunities Exceptional credit in similar businesses Historically strong organic loan growth Exceptional credit quality with 0.14% NPA/Assets (2) Very similar loan profile to PacWest’s Community Bank Division Closing Date: October 20, 2017 Transaction Value: $671 million in aggregate (1) Consideration Mix: 70% PACW common stock / 30% cash Fixed Exchange Ratio: 0.5308x Cash per Share: $12.00 Transaction Summary Improves Deposit and Liquidity Position Outstanding deposit franchise: 55% non-interest bearing deposits; 15 basis point total cost of deposits (2) Large efficient branches similar to PacWest’s existing network Asset-sensitive balance sheet consistent with PacWest’s asset-liability profile Liquid balance sheet with 78% loan-to-deposits ratio (2) Based on PacWest’s closing price on October 20, 2017. Financial data as of 9/30/2017.

CU Bancorp – Closing Balance Sheet (10/20/17)* MTM/ Adjusted Purchase Pro PacWest CUB Adjustments CUB Accounting Forma Assets: Cash and Securities 3,819 $ 848 $ (4) $ (1) 844 $ (237) $ (5) 4,426 $ Gross Loans 15,691 2,100 (24) (2) 2,076 - 17,767 Loan Loss Reserve (160) (19) 19 (2) - - (160) Net Loans 15,531 2,081 (5) 2,076 - 17,607 Other Tangible Assets 692 120 - 120 (13) (6) 799 Total Tangible Assets 20,042 3,049 (9) 3,040 (250) 22,832 Goodwill 2,174 65 (65) (3) - 375 (7) 2,549 Other Intangibles 27 5 (5) (3) - 58 (8) 85 Intangible Assets 2,201 70 (70) - 433 2,634 Total Assets 22,243 $ 3,119 $ (79) $ 3,040 $ 183 $ 25,466 $ Liabilities & Shareholders' Equity: Deposits 16,773 $ 2,720 $ - $ 2,720 $ - $ 19,493 $ Borrowings 699 34 - 34 - 733 Other Liabilities 160 22 9 (4) 31 - 191 Liabilities & Borrowings 17,632 2,776 9 2,785 - 20,417 Shareholders' Equity 4,611 343 (88) 255 183 (9) 5,049 Liabilities & Shareholders' Equity 22,243 $ 3,119 $ (79) $ 3,040 $ 183 $ 25,466 $ * Pro forma information is based on estimates and is subject to change upon completion of CUB final tax returns. Notes: (1) To record FV mark on investment securities (2) To record FV mark on loans and eliminate CUB's ALLL (3) To eliminate CUB's goodwill and intangibles (4) To record FV mark on reserve for unfunded commitments and other liabilities (5) Estimated after-tax purchaser transaction costs and cash consideration (6) Estimated net DTL related to FV marks and CDI (7) Estimated transaction goodwill (8) Estimated CDI at 2.15% of core deposits (9) To reflect equity portion of the purchase price, net of estimated after-tax purchaser transaction costs and goodwill Standalone 10/20/17

Strong Franchise Value

National Lending Combined With California Branch Network Source: SNL Financial Los Angeles, CA Durham, NC Chevy Chase, MD Chicago, IL St. Louis, MO Denver, CO New York, NY Boston, MA Minneapolis, MN Austin, TX Campbell, CA Menlo Park, CA San Francisco, CA Seattle, WA Atlanta, GA San Diego, CA CapitalSource Division office Square 1 Bank Division office Pacific Western Bank branch

Source: SNL Financial using data as of 1/30/2018 California Public Banks and Thrifts As of December 31, 2017 Rank Company Name Ticker Assets ($000) 1 Wells Fargo & Company WFC $ 1,951,757,000 2 First Republic Bank FRC $ 87,750,507 3 SVB Financial Group SIVB $ 51,214,467 4 East West Bancorp, Inc. EWBC $ 37,150,249 5 PacWest Bancorp PACW $ 24,994,876 6 Cathay General Bancorp CATY $ 15,728,417 7 Hope Bancorp, Inc. HOPE $ 14,150,021 8 Banc of California, Inc. BANC $ 10,327,852 9 BofI Holding, Inc. BOFI $ 8,581,628 10 CVB Financial Corp. CVBF $ 8,270,586 11 Pacific Premier Bancorp, Inc. PPBI $ 8,024,501 12 Opus Bank OPB $ 7,486,809 13 Farmers & Merchants Bank of Long Beach FMBL $ 6,991,578 14 Luther Burbank Corporation LBC $ 5,704,380 15 Mechanics Bank MCHB $ 5,702,388 16 Westamerica Bancorporation WABC $ 5,513,046 17 Hanmi Financial Corporation HAFC $ 5,210,485 18 TriCo Bancshares TCBK $ 4,656,435 19 First Foundation, Inc. FFWM $ 4,051,061 20 Preferred Bank PFBC $ 3,769,859 21 Community Bank CYHT $ 3,747,398 22 Grandpoint Capital Inc. GPNC $ 3,193,934 23 Farmers & Merchants Bancorp FMCB $ 3,071,775 24 1867 Western Financial Corporation WFCL $ 2,906,569 25 Heritage Commerce Corp HTBK $ 2,843,577 26 Bank of Marin Bancorp BMRC $ 2,468,154 27 Sierra Bancorp BSRR $ 2,340,298 28 Exchange Bank EXSR $ 2,258,824 29 River City Bank RCBC $ 2,037,816 30 American Business Bank AMBZ $ 1,752,656

The Company uses certain non-GAAP financial measures to provide meaningful supplemental information regarding the Company’s operational performance and to enhance investors’ overall understanding of such financial performance. These non-GAAP financial measures should not be considered a substitute for financial information presented in accordance with GAAP and may be different from non-GAAP financial measures used by other companies. The table on the following slide presents reconciliations of certain GAAP to non-GAAP financial measures. Non-GAAP Measurements

Tangible Common Equity Ratio/Tangible Book Value Per Share December 31, September 30, June 30, March 31, December 31, ($ in thousands, except per share amounts) 2017 2017 2017 2017 2016 Tangible Common Equity Ratio & Tangible Book Value Per Share Stockholders' equity 4,977,598 $ 4,610,668 $ 4,559,905 $ 4,508,106 $ 4,479,055 $ Less: Intangible assets 2,628,296 2,201,137 2,204,186 2,207,251 2,210,315 Tangible common equity 2,349,302 $ 2,409,531 $ 2,355,719 $ 2,300,855 $ 2,268,740 $ Total assets 24,994,876 $ 22,242,932 $ 22,246,877 $ 21,927,254 $ 21,869,767 $ Less: Intangible assets 2,628,296 2,201,137 2,204,186 2,207,251 2,210,315 Tangible assets 22,366,580 $ 20,041,795 $ 20,042,691 $ 19,720,003 $ 19,659,452 $ Equity to assets ratio 19.91% 20.73% 20.50% 20.56% 20.48% Tangible common equity ratio (1) 10.50% 12.02% 11.75% 11.67% 11.54% Book value per share 38.65 $ 37.96 $ 37.55 $ 37.13 $ 36.93 $ Tangible book value per share (2) 18.24 $ 19.84 $ 19.40 $ 18.95 $ 18.71 $ Shares outstanding 128,782,878 121,449,794 121,448,321 121,408,133 121,283,669 Return on Average Tangible Equity Net earnings 84,037 $ 101,466 $ 93,647 $ 78,668 $ 85,647 $ Average stockholders' equity 4,920,498 $ 4,592,489 $ 4,545,276 $ 4,503,675 $ 4,501,948 $ Less: Average intangible assets 2,495,876 2,202,922 2,205,814 2,209,112 2,212,042 Average tangible common equity 2,424,622 $ 2,389,567 $ 2,339,462 $ 2,294,563 $ 2,289,906 $ Return on average equity 6.78% 8.77% 8.26% 8.24% 8.05% Return on average tangible equity (3) 13.75% 16.85% 16.06% 13.90% 14.88% (1) Tangible common equity divided by tangible assets (2) Tangible common equity divided by shares outstanding (3) Annualized net earnings divided by average tangible common equity PacWest Bancorp Consolidated