Exhibit 99.1

PRESS RELEASE

PacWest Bancorp

(NASDAQ: PACW)

PACWEST BANCORP ANNOUNCES RESULTS

FOR THE FIRST QUARTER OF 2011

—Net Earnings of $10.7 Million—

—Net Interest Margin Increases to 5.34%—

—Credit Loss Reserve at 3.41% of Net Non-Covered Loans—

—Core Deposits Grow $53.1 Million—

—Noninterest-Bearing Deposits at 35% of Total Deposits—

Los Angeles, California . . . PacWest Bancorp (Nasdaq: PACW) today announced net earnings for the first quarter of 2011 of $10.7 million, or $0.29 per diluted share, compared to a net loss of $7.7 million, or $0.22 per diluted share, for the fourth quarter of 2010.  The $18.4 million increase in net earnings for the linked quarters was due primarily to a lower credit loss provision on non-covered loans of $27.5 million ($16.0 million after-tax) and lower noninterest expense of $7.9 million ($4.6 million after-tax).

This press release contains non-GAAP financial disclosures for tangible common equity.  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.  Given the use of tangible common equity amounts and ratios is prevalent among banking regulators, investors and analysts, we disclose our tangible common equity ratios in addition to equity-to-assets ratios.  Also, as analysts and investors view pre-credit, pre-tax earnings as an indicator of the Company’s ability to absorb credit losses, we disclose this amount in addition to net earnings.  Please refer to the table at the end of this release for a presentation of performance ratios in accordance with GAAP and a reconciliation of the non-GAAP financial measures to the GAAP financial measures.

1

FIRST QUARTER RESULTS

(1) FDIC loss sharing income and net covered OREO costs reduced the first quarter 2011 and increased fourth quarter 2010 efficiency ratios by 491 bps and 209 bps, respectively.

(2) Non-covered loans exclude loans from the Los Padres and Affinity acquisitions covered by a loss sharing agreement with the FDIC.

The improvement in first quarter net earnings compared to the prior quarter was due to a combination of lower provision for credit losses on non-covered loans, higher FDIC loss sharing income, and lower noninterest expense, offset partially by lower net interest income.  Net interest income declined due primarily to lower average loans during the current quarter attributable to the $74.9 million classified loan sale in December 2010 and the continuing decline in the loan portfolio. FDIC loss sharing income grew principally due to an increase in covered loan credit costs. Noninterest expense decreased mostly due to lower compensation costs, OREO costs and other expense.

2

Net credit costs on a pre-tax basis are shown in the following table:

The credit loss provision for the first quarter had two components: $7.8 million for non-covered loans and $5.7 million for covered loans.  The first quarter non-covered credit loss provision was driven by (a) non-covered loan net charge-offs of $7.9 million and (b) the level and trends of nonaccrual and classified loans.   The covered loan credit loss provision was driven by decreases in expected cash flows on covered loans compared to those previously estimated.  The covered loan credit loss provision and covered net OREO income or expense are offset partially by an increase in the FDIC loss sharing asset, which represents the FDIC’s share of these net costs.

Matt Wagner, Chief Executive Officer, commented, “We are very pleased with the positive earnings we generated this quarter.  As we commented previously, we have maintained our solid core earnings engine, which was overshadowed by higher provisioning during the past several quarters as we addressed this credit cycle head-on.  Our core earnings generation ability and balance sheet strength gives us the flexibility to address issues timely and appropriately.”

“In addition to our solid first quarter earnings performance,” continued Mr. Wagner, “we substantially increased core deposits through organic growth.   While we remain vigilant about credit and cautious on its outlook, we are well-positioned to take advantage of potential growth opportunities.  Our Company remains well-capitalized and our balance sheet strength is evidenced by our credit loss reserve coverage ratios of 3.4% to total loans and 136% to nonaccrual loans.”

Vic Santoro, Executive Vice President and Chief Financial Officer, stated, “The events of the first quarter reflect the strengths of our core business and the focus we’ve had on earnings improvement.  Our net interest margin expanded to the level it was in 2008, our all-in deposit cost remains quite low, and noninterest expenses are managed.  On a pre-credit, pre-tax basis, our earnings exceeded $28 million for the first quarter.  Our core deposits increased over $53 million and noninterest-bearing deposits were at 35% of total deposits at quarter-end.”

3

Mr. Santoro continued, “The Company’s cash and available-for-sale securities exceed $1 billion and represent almost 20% of assets at quarter-end.  Our capital position is strong, as the earnings generated in the first quarter contributed to increases in total capital of over $12 million and tangible capital of over $15 million.  The combination of strong liquidity and capital enables us to take advantage of growth opportunities as they arise.”

BALANCE SHEET CHANGES

During the first quarter total loans declined $152.5 million on a net basis, including a $103.4 million decrease in non-covered loans.  The loan portfolio continues to decline generally due to repayments, resolution activities and low loan demand.  Non-covered loans, net of unearned income, were $3.1 billion at March 31, 2011 and the covered loan portfolio was $859.4 million at March 31, 2011.

While total assets declined $58.5 million during the first quarter, on-balance sheet liquidity increased $98.1 million, including a $78.6 million increase in overnight funds held at the Federal Reserve Bank.  Investment securities available-for-sale grew $13.1 million during the first quarter due to the purchase of $71.1 million in government-sponsored entity pass through securities, offset partially by principal reductions.

Total deposits declined $65.0 million during the first quarter to $4.6 billion at March 31, 2011 largely as a result of brokered deposit maturities and runoff of higher cost acquired time deposit accounts.  Time deposits decreased $118.1 million during the first quarter, including brokered deposit maturities of $36.2 million, to $1.1 billion at March 31, 2011.  We had no brokered deposits at March 31, 2011.  Core deposits, which include noninterest-bearing demand, interest checking, money market and savings accounts, increased $53.1 million during the first quarter and totaled $3.5 billion at March 31, 2011, or 76% of total deposits at that date.  Noninterest-bearing demand deposits grew $140.6 million during the first quarter to $1.6 billion and represented 35% of total deposits at March 31, 2011.

COVERED ASSETS

As part of the Los Padres and Affinity acquisitions we entered into loss sharing agreements with the FDIC that cover a substantial portion of losses incurred after the acquisition dates on loans and other real estate owned, and in the case of the Affinity acquisition, certain investment securities.

4

A summary of the covered assets at March 31, 2011 and December 31, 2010 is shown in the following table:

NET INTEREST INCOME

Net interest income was $65.7 million for the first quarter of 2011 compared to $68.5 million for the fourth quarter of 2010.  The $2.8 million decline is due mostly to a $3.2 million decrease in interest income, which is attributed mainly to lower average loans as a result of the $74.9 million classified loan sale in the fourth quarter and the continued decline of the loan portfolio from loan payoffs.  Partially offsetting the decline in net interest income was a reduction in interest expense of $459,000 due mainly to the early repayment of $50 million in FHLB advances during the fourth quarter of 2010.

NET INTEREST MARGIN

Our net interest margin for the first quarter of 2011 was 5.34%, an increase of 13 basis points from the 5.21% posted for the fourth quarter of 2010. The yield on average loans was 6.78% for the first quarter of 2011 compared to 6.64% for the prior quarter.  The loan yield, earning asset yield and net interest margin are all affected by loans being placed on or removed from nonaccrual status and the acceleration of purchase discounts on covered loan pay-offs; the loan yield and net interest margin for the first quarter were positively impacted by 27 basis points and 22 basis points, respectively, from the combination of these items.  The loan yield and net interest margin for the fourth quarter were positively impacted by 20 basis points and 16 basis points, respectively, from these items.  The cost of interest-bearing deposits and all-in deposit cost increased 6 basis points and 2 basis points to 0.79% and 0.52%, respectively, due mostly to an increase in the cost of time deposits.  The cost of time deposits increased primarily from lower discount accretion on certain acquired time deposits, the maturities of brokered deposits having a lower rate than the overall time deposit rate, and an increase in the average remaining life of the time deposit portfolio.

NONINTEREST INCOME

Noninterest income for the first quarter of 2011 totaled $7.6 million compared to $4.6 million for the fourth quarter of 2010.  The $3.0 million increase was due mostly to higher FDIC loss sharing income stemming from higher credit-related net costs on covered loans and OREO.  Contributing to the growth in noninterest income was an increase in service charges on deposit accounts attributable to mid-quarter increases in rates charged for certain deposit services.

5

NONINTEREST EXPENSE

Noninterest expense totaled $41.4 million for the first quarter of 2011 compared to $49.3 million for the fourth quarter of 2010.  The $7.9 million decline was due mostly to decreases in compensation expense, covered OREO costs and other expense.  Compensation expense decreased by $2.0 million due mostly to a higher discretionary bonus accrual in the prior quarter.   Covered OREO costs decreased by $3.3 million due principally to a $3.3 million gain on sale of one commercial real estate property during the current quarter.  Other expense declined by $2.2 million due mostly to a $1.9 million penalty recorded in the prior quarter for the early repayment of $50 million in FHLB advances; there was no similar expense item in 2011.  We consolidated five acquired Los Padres branches into nearby branch locations in February 2011.

Noninterest expense includes amortization of time-based restricted stock, which is included in compensation, and intangible asset amortization.  Amortization of restricted stock totaled $2.0 million for the first quarter of 2011 and $1.9 million for the fourth quarter of 2010.  Intangible asset amortization totaled $2.3 million and $2.4 million for the first quarter of 2011 and the fourth quarter of 2010, respectively.

CREDIT QUALITY

(1) Classified loans are those with a credit risk rating of substandard or doutbtful.

Credit Loss Provisions

The first quarter of 2011 provision for credit losses totaled $13.5 million and was composed of $7.8 million on the non-covered loan portfolio and $5.7 million on the covered loan portfolio. The fourth quarter provision for credit losses totaled $37.4 million and was composed of $35.3 million on the non-covered loan portfolio, including $14.3 million attributed to the December classified loan sale, and $2.1 million on the covered loan portfolio.  The provision on the non-covered portfolio is generated by our allowance methodology and reflects net charge-offs, the levels of nonaccrual and classified loans, and the migration of loans into various risk classifications.  The covered loan credit loss provision increases the covered loan allowance for credit losses and results from decreases in expected cash flows on covered loans compared to those previously estimated.

6

First quarter of 2011 net charge-offs on non-covered loans totaled $7.9 million compared to fourth quarter net charge-offs on non-covered loans of $32.2 million. The fourth quarter net charge-offs included $20.9 million in charge-offs from the $74.9 million of classified loans sold in the same quarter. The allowance for credit losses on the non-covered portfolio totaled $104.2 million and $104.3 million at March 31, 2011 and December 31, 2010, respectively, and represented 3.41% and 3.30% of the non-covered loan balances at those respective dates.  The allowance for credit losses as a percent of nonaccrual loans was 136% and 111% at March 31, 2011 and December 31, 2010, respectively.

Non-covered Nonaccrual Loans and Other Real Estate Owned

Non-covered nonperforming assets include non-covered nonaccrual loans and non-covered OREO and totaled $125.2 million at March 31, 2011 compared to $119.8 million at December 31, 2010. The $5.4 million increase in non-covered nonperforming assets is due primarily to a higher non-covered OREO balance at March 31, 2011.  During the first quarter of 2011, two non-covered nonaccrual loans with an aggregate balance of $23.0 million secured by the same undeveloped land located in Ventura County were foreclosed and transferred to non-covered OREO.  The ratio of non-covered nonperforming assets to non-covered loans and non-covered OREO increased to 4.03% at March 31, 2011 from 3.76% at December 31, 2010.

The amount of new nonaccrual loans has slowed over the last several quarters as shown in the following chart.

7

The types and balances of non-covered loans included in the categories of nonaccrual and accruing loans past due between 30 and 89 days at March 31, 2011 and December 31, 2010 follow:

(1) Excludes covered loans acquired from the Los Padres and Affinity acquisitions.

The $17.3 million decline in non-covered nonaccrual loans during the first quarter was attributable to (a) foreclosures of $25.1 million, (b) other reductions, payoffs and returns to accrual status of $6.6 million, (c) charge-offs of $8.8 million, and (d) additions of $23.2 million.

8

The following lending relationships, excluding SBA-related loans, were on nonaccrual status at March 31, 2011:

The details of non-covered OREO as of the dates indicated follow:

9

The activity in non-covered and covered OREO for the first quarter is shown in the following table:

The increase in non-covered OREO relates to the foreclosure on undeveloped land located in Ventura County which secured two non-covered loans with an aggregate balance of $23.0 million.   During the first quarter of 2011, there were gains of $152,000 and $3.8 million on the sales of non-covered and covered OREO, respectively.

REGULATORY CAPITAL MEASURES ARE ABOVE THE WELL-CAPITALIZED MINIMUMS

PacWest and its wholly-owned banking subsidiary, Pacific Western Bank, each remained well capitalized at March 31, 2011 as shown in the following table.

ABOUT PACWEST BANCORP

PacWest Bancorp (“PacWest”) is a bank holding company with $5.5 billion in assets as of March 31, 2011, with one wholly-owned banking subsidiary, Pacific Western Bank (“Pacific Western”). Through 77 full-service community banking branches, Pacific Western provides commercial banking services, including real estate, construction and commercial loans, to small and medium-sized businesses. Pacific Western’s branches are located in Los Angeles, Orange, Riverside, San Bernardino, Santa Barbara, San Diego, San Francisco, San Luis Obispo, San Mateo and Ventura Counties in California and Maricopa County in Arizona.  Through its subsidiary BFI Business Finance and its division First Community Financial, Pacific Western also provides working capital financing to growing companies located throughout the Southwest, primarily in the states of Arizona, California and Texas. Additional information regarding PacWest Bancorp is available on the Internet at www.pacwestbancorp.com.  Information regarding Pacific Western Bank is also available on the Internet at www.pacificwesternbank.com.

10

FORWARD-LOOKING STATEMENTS

This press release contains certain forward-looking information about PacWest 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 the Company. We caution readers that a number of important factors could cause actual results to differ materially from those expressed in, implied or projected by, such forward-looking statements. Risks and uncertainties 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 Company’s ability to complete future acquisitions, successfully integrate such acquired entities, or achieve expected beneficial synergies and/or operating efficiencies within expected time-frames or at all; settlements with the FDIC related to our loss-sharing arrangement and other adjustments related to the Los Padres Bank and Affinity Bank acquisitions; the possibility that personnel changes will not proceed as planned; the cost of additional capital is more than expected; a change in the interest rate environment reduces interest margins; asset/liability repricing risks and liquidity risks; pending legal matters may take longer or cost more to resolve or may be resolved adversely to the Company; general economic conditions, either nationally or in the market areas in which the Company does or anticipates doing business, are less favorable than expected; environmental conditions, including natural disasters, may disrupt our business, impede our operations, negatively impact the values of collateral securing the Company’s loans or impair the ability of our borrowers to support their debt obligations; the economic and regulatory effects of the continuing war on terrorism and other events of war, including the conflicts in the Middle East; legislative or regulatory requirements or changes adversely affecting the Company’s business; and changes in the securities markets; regulatory approvals for any capital activities cannot be obtained on the terms expected or on the anticipated schedule; and, other risks that are described in PacWest’s public filings with the U.S. Securities and Exchange Commission (the “SEC”). If any of these risks or uncertainties materializes or if any of the assumptions underlying such forward-looking statements proves to be incorrect, PacWest’s results could differ materially from those expressed in, implied or projected by such forward-looking statements. PacWest assumes no obligation to update such forward-looking statements.

For a more complete discussion of risks and uncertainties, investors and security holders are urged to read PacWest Bancorp’s annual report on Form 10-K, quarterly reports on Form 10-Q and other reports filed by PacWest with the SEC.  The documents filed by PacWest with the SEC may be obtained at PacWest Bancorp’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 directing a request to: PacWest Bancorp c/o Pacific Western Bank, 275 North Brea Boulevard, Brea, CA 92821.  Attention: Investor Relations. Telephone 714-671-6800.

11

PACWEST BANCORP AND SUBSIDIARIES

CONDENSED CONSOLIDATED BALANCE SHEETS

(Unaudited)

12

PACWEST BANCORP AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF EARNINGS (LOSS)

(Unaudited)

13

PACWEST BANCORP AND SUBSIDIARIES

AVERAGE BALANCE SHEETS AND YIELD ANALYSIS

(Unaudited)

(1) Average funding sources is the sum of average interest-bearing liabilities plus average noninterest-bearing deposits.

(2) Interest rate spread is calculated as the yield on average interest-earning assets less the cost of average interest-bearing liabilities.

(3) Net interest rate margin is calculated as annualized net interest income divided by average interest-earning assets.

(4) Cost of average deposits is calculated as annualized interest expense on deposits divided by average deposits.

(5) Cost of average funding sources is calculated as annualized total interest expense divided by average funding sources.

14

PACWEST BANCORP AND SUBSIDIARIES

NON-COVERED LOAN CONCENTRATION

(Unaudited)

PACWEST BANCORP AND SUBSIDIARIES

COVERED LOAN CONCENTRATION

(Unaudited)