Columbia Banking System 8K Form of Voting Andnon-competition Agreement | COLB 10 Jan 17

Acquisition of

Pacific Continental Corporation

January 10, 2017

Investor Presentation

Exhibit 99.4

Cautionary Note: Forward-looking Statements

This presentation includes forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. All statements

other than statements of historical fact are forward-looking statements. These forward-looking statements involve known and unknown risks,

uncertainties and other factors which may cause Columbia Banking System, Inc.’s (“Columbia”) or Pacific Continental Corporation’s (“PCBK”)

performance or achievements to be materially different from any expected future results, performance, or achievements.

Forward-looking statements speak only as of the date they are made and neither Columbia nor PCBK assumes any duty to update forward-looking

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. Such forward-looking statements include, but are not limited to, statements about the

benefits of the business combination transaction involving Columbia and PCBK, including future financial and operating results, the combined

company’s plans, objectives, expectations and intentions and other statements that are not historical facts. The following factors, among others,

could

cause

actual

results

differ

from

those

set

forth

the

forward-looking

statements:

(i)

the

possibility

that

the

merger

does

not

when

expected or at all because required regulatory, shareholder or other approvals and other conditions to closing are not received or satisfied on a

timely basis or at all; (ii) changes in Columbia’s stock price before closing, including as a result of the financial performance of PCBK prior to closing,

generally

due

broader

stock

market

movements,

and

the

performance

financial

companies

and

peer

group

companies;

(iii)

the

risk

that the benefits from the transaction may not be fully realized or may take longer to realize than expected, including as a result of changes in

general economic and market conditions, interest and exchange rates, monetary policy, laws and regulations and their enforcement, and the degree

of competition in the geographic and business areas in which Columbia and PCBK operate; (iv) the ability to promptly and effectively integrate the

businesses of Columbia and PCBK; (v) the reaction to the transaction of the companies’ customers, employees and counterparties; (vi) diversion of

management time on merger-related issues; (vii) lower than expected revenues, credit quality deterioration or a reduction in real estate values or a

reduction in net earnings; and (viii) other risks that are described in Columbia’s and PCBK’s public filings with the Securities and Exchange

Commission (the “SEC”). For more information, see the risk factors described in each of Columbia’s and PCBK’s Annual Reports on Form 10-K,

Quarterly Reports on Form 10-Q and other filings with the SEC.

Annualized, pro forma, projected and estimated numbers and percentages are used for illustrative purposes only, are not forecasts and may not

reflect actual results.

Transaction Highlights

Transaction

Rationale

Attractive

Financial

Returns

•

Strengthens COLB’s presence in key metropolitan markets in the Northwest

Significantly increases COLB’s market share in the Eugene MSA and provides opportunities to

enhance efficiency in the Seattle and Portland markets

•

PCBK is the 2

largest community bank headquartered in Oregon with $2.5 billion in assets

•

Solidifies Columbia as the largest bank solely focused on the NW with ~$12 billion in assets

•

Complementary community-focused banking models built around strong core deposit cultures

Noninterest bearing deposits of 49% and 42% for COLB and PCBK, respectively

•

Expands healthcare lending platform

•

Delivers COLB’s expanded product suite and higher lending capacity to PCBK’s customer base

•

~8% earnings accretion in 2018 and ~10% earnings accretion in 2019

•

> 15% IRR

•

Tangible Book Value Earnback of ~3.7 years

•

~6% TBV Dilution at Close

Risk

Management

•

Pro forma assumptions driven by significant due diligence

•

COLB is well-positioned to cross the $10 billion asset threshold

•

Track

record

successfully

integrated

acquisitions

over

the

last

years

(1)

Based on COLB’s closing stock price as of 1/9/17. Merger consideration value and price per share will change, and partial cash consideration may be included,

based on the fluctuation in COLB’s stock price. Please see Appendix.

(2)

Includes aggregate stock consideration of $629.5 million paid to PCBK shareholders and aggregate cash consideration of $14.6 million to cash out all outstanding

stock options, stock appreciation rights (“SARs”) and restricted stock units (“RSUs”) at close.

Transaction Overview

Aggregate transaction value of ~$644.1 million

Transaction Value

(1)(2)

Price per Share

(1)

Consideration

Pro Forma Ownership

Board

Due Diligence

Termination Fee

Required Approvals

Targeted Closing

$27.85

Fixed exchange ratio of 0.6430; subject to adjustments described below

100% stock consideration to PCBK shareholders

80.0% COLB / 20.0% PCBK

One current community-based board member from PCBK to join COLB Board of

Directors; pro forma board will have 12 members

Completed, including an extensive loan review

$18.75 million for superior offer and other customary events

Customary regulatory and shareholder approvals

Mid-2017

Collars & Walkaway

Fixed exchange ratio when COLB stock is between $27.76 and $37.56;

Outside the range, price fixes if COLB outperforms (above the range)/underperforms

(below the range) the KBW Regional Bank Index by 15% or more;

COLB and PCBK have termination rights should COLB stock drop below $26.13 (with PCBK’s

right to reinstate by including per share cash consideration of $1.05)

*Note: PCBK branches excludes branch in Bellevue that is expected to be closed in January 2017.

Source: SNL Financial, company websites, and Microsoft MapPoint.

COLB (143)

PCBK (14)*

Compelling Northwest Footprint

Pacific Continental Corporation (NASDAQ: PCBK)

Profitability (MRQ)

(%)

ROAA, Adjusted

(2)

1.02

ROATCE, Adjusted

(2)

10.96

Net Interest Margin

4.22

Efficiency Ratio, Adjusted

(2)

54.8

Asset Quality

(%)

NPAs

(3)

/ Assets

0.90

NPAs

(3)

/ (Loans + OREO)

1.25

Reserves / Loans HFI

1.14

LTM NCOs / Avg. Loans

0.01

Balance Sheet & Capital

(%)

Loans / Deposits

83.5

Securities / Assets

19.2

Noninterest-bearing Deposits / Deposits

41.7

TCE / TA

8.34

Total Risk-based Capital Ratio

12.55

Financials as of 9/30/2016

Assets ($mm)

2,539

Deposits ($mm)

2,163

Gross Loans ($mm)

1,807

Tangible Common Equity ($000)

206

PCBK Market Presence

Overview of PCBK

•

Founded in 1972 with headquarters in Eugene, OR

•

Completed 4 acquisitions since 2005

•

Specialized business segments

Community-based business

Healthcare and professional services

Nonprofit clients

•

14 branch offices

(1)

, 2 loan production offices

•

Average deposits per branch of $155 million

•

“PLUS” –

loans for dental acquisition, practice finance, and owner

occupied CRE in 42 states

(1)

PCBK branches excludes branch in Bellevue that is expected to be closed in January 2017.

(2)

Adjusted to exclude impact from Foundation Bancorp, Inc. acquisition.

(3)

Excludes troubled debt restructurings.

Source: SNL Financial. Data for the quarter ended 9/30/2016.

Source: SNL Financial. Deposit market share data pro forma per FDIC S.O.D. as of 6/30/2016.

Rank

Institution (ST)

Number

Branches

Deposits in

Market

($mm)

Market

(%)

Pacific Continental Corp. (OR)

855

17.1

Umpqua Holdings Corp. (OR)

833

16.7

U.S. Bancorp (MN)

802

16.0

Wells Fargo & Co. (CA)

628

12.6

Bank of America Corp. (NC)

334

6.7

Banner Corp. (WA)

329

6.6

JPMorgan Chase & Co. (NY)

327

6.5

KeyCorp (OH)

238

4.8

Summit Bank (OR)

226

4.5

Oregon Pacific Bancorp (OR)

136

2.7

Washington Federal Inc. (WA)

121

2.4

Cascade Bancorp (OR)

1.7

Citizens Bancorp (OR)

1.1

Columbia Banking System Inc. (WA)

0.6

Totals (1-14)

5,000

100.0

PCBK’s Geographic Footprint

Loan Mix by Geography

Eugene MSA Deposit Market Share

•

Eugene is the 2

largest MSA in Oregon by number of

households

•

Home to the University of Oregon, the Eugene market is

known for supporting entrepreneurial investment, which

is locally referred to as the Silicon Shire, representing

dozens of start-up technology companies

•

Unemployment in the Eugene market is less

than 5%

Stronghold in the Eugene Market

Deposit Mix by Geography

Loan Mix ($mm)

Eugene

405

Portland

729

Puget Sound

424

Nat'l Healthcare

251

Gross Loans

1,809

Deposit Mix ($mm)

Eugene

785

Portland

672

Puget Sound

593

Non-core

113

Total Deposits

2,163

Eugene

22%

Portland

40%

Puget Sound

24%

Nat'l

Healthcare

14%

Eugene

36%

Portland

31%

Puget Sound

28%

Non-core

Note: Period end dollars in millions.

Pacific Continental’s Dental and Healthcare Niche

Demonstrated Dental Expertise

•

10 plus years demonstrated expertise

•

More than 500 practices

•

Since 2008, annual loan losses less than 0.20%

•

Represents 26.6% of loan portfolio

Demonstrated Healthcare Expertise

•

Veterinary services

•

Ophthalmology

•

Podiatry

$122

$160

$158

$166

$192

$179

$159

$146

$150

$152

$151

$20

$42

$79

$129

$147

$194

$201

$218

$219

$10

$25

$54

$62

$69

$73

$72

$80

$23

$29

$33

$32

$50

$100

$150

$200

$250

$300

$350

$400

$450

$500

Other Healthcare National

Other Healthcare Local

Dental National

Dental Local

Pro Forma Financial Impact

(1)

Based on COLB’s closing stock price as of 1/9/17. Merger consideration value and price per share will change, and partial cash consideration may be included,

based on the fluctuation in COLB’s stock price. Please see Appendix.

(2)

Per

party

loan

review.

(3)

Core deposits equal to all non-time deposits.

(4)

Adjustments based on projected balances at close.

Cost Savings

Deal Related Expenses

Revenue

Enhancements

•

Estimated Core Deposit Intangible equaling 1.75% of PCBK’s core

deposits

(3)

•

Estimated Fixed Asset markup of $2.8 million; estimated OREO

markdown of $2.3 million

•

Estimated Subordinated debt markup of $1.1 million

•

Trust Preferred Redemption of $14.0 million; reversal of the $2.6 million

Foundation Trust Preferred Mark

•

Estimated PCBK Durbin pre-tax annual impact of $300 thousand starting

July 2018

Estimated Fair Value

and Pro Forma

Adjustments

(4)

•

Not included

•

Approximately $30.4 million, pre-tax

•

Estimated at approximately $19.4 million or 34% of PCBK’s 2017e NIE

•

Expected to be phased 50% in 2017, 85% in 2018 and 100% thereafter

•

Estimated

gross

loan

mark

$33.1

million

1.70%

loans

(2)

Loan Mark

(4)

Transaction Value

(1)

•

~$644.1 million

Transaction Assumptions and Pro Forma Adjustments

(1)

Per FactSet Research Systems.

•

Cost

savings

~34%

PCBK’s

2017e

consensus

street

noninterest

expense

(1)

Expense Items

Approximate

Value

in Millions

Salary & Benefits

$13.1

Occupancy, Equipment &

Amortization

$0.8

Data processing & Communications

$1.6

General & Administrative

$3.2

Other

$0.7

TOTAL

$19.4

Cost Savings

(1)

Date of the U.S. Presidential Election. COLB’s stock price has increased by 30.5% and the KRX index price has increased by 24.8% since the U.S. Presidential

Election.

(2)

Core deposits equal to all non-time deposits.

(3)

Assumes 85% phase-in of cost savings.

(4)

Assumes 100% phase-in of cost savings.

(5)

Tangible Book Value Earnback Period measures the number of years required for the pro forma company’s projected TBVPS to exceed the projected TBVPS of the

standalone Columbia.

(6)

Assumes conversion of COLB’s convertible preferred equity.

Pro Forma Financial Impact

PCBK Acquisition as of

Transasction Multiples (as of 9/30/2016)

11/8/2016

(1)

1/9/2017

Price / Tangible Book Value Per Share:

2.34x

3.06x

Price / 2017e EPS:

16.2x

21.2x

Core Deposit Premium

(2)

13.8%

21.1%

One-Day Market Premium:

28.6%

33.9%

Transaction Metrics

2018 Estimated EPS Accretion

(3)

~8%

2019 Estimated EPS Accretion

(4)

~10%

Internal Rate of Return:

> 15%

Tangible Book Value Per Share Earnback

(5)

~3.7 years

Consolidated Capital Ratios (Estimated as of 6/30/2017)

(6)

Pro Forma

TCE / TA:

9.3%

8.3%

8.7%

Leverage Ratio:

9.6%

8.9%

Common Equity Tier 1 Capital Ratio:

11.6%

9.6%

10.7%

Tier 1 Ratio:

11.6%

10.1%

10.7%

Total Risk-based Capital Ratio:

12.6%

12.7%

11.8%

•

Accelerates our growth over $10 billion in total assets into mid-2017

•

COLB started preparing to cross $10 billion in January 2013. Significant infrastructure

expenses have already been built into our run rate; efforts to date include:

Implemented a robust Compliance Management Program with area compliance experts

embedded within the various functional areas of the bank resulting in an enhanced

compliance-oriented culture

Developed and implemented in 2014 a DFAST compliant stress test model

Expanded the Executive Management team with the addition of the General Counsel function

Various shifts in the senior and middle management organizational structure to more

efficiently manage across a larger asset base

Implemented various Board level corporate governance initiatives, including the addition of

new directors with diversified professional backgrounds and expanded geographic reach, and

improved utilization of board committees

Continue to develop and mature our Enterprise Risk Management program

•

Subjects COLB to Durbin Amendment in Q3 of 2018 resulting in an annual estimated

loss of pre-tax interchange revenue on a combined proforma basis of approximately

$9.8 million

Surpassing the $10 Billion Asset Threshold

•

Acquisition is in line with COLB’s strategic plan, and meets COLB’s investment

criteria

•

PCBK provides COLB a solid foothold in the Eugene market with #1 market share

rank and the opportunity to combine some branches in the Seattle and Portland

markets

•

Culturally compatible banks with similar core deposit bases and commercial

banking orientation

•

Increased size and scale favorably positions COLB for further growth strategies

•

Transaction expected to enhance COLB’s long-term shareholder value

Attractive Investment Opportunity

APPENDIX

Per PCBK Common Share

Price Change

Price

Ex Ratio

Total Value

Equity Awards

Total Value

(%)

($)

(x)

($)

(#)

($000)

Price on 1/9/2017

43.31

0.6430

27.85

14,535,729

14,572

644,115

15.0%

$37.56

0.6430

$24.15

14,535,729

$11,791

$557,753

12.5%

36.74

0.6430

23.62

14,535,729

11,394

545,437

10.0%

35.93

0.6430

23.10

14,535,729

11,002

533,271

7.5%

35.11

0.6430

22.58

14,535,729

10,606

520,955

5.0%

34.29

0.6430

22.05

14,535,729

10,209

508,639

2.5%

33.48

0.6430

21.53

14,535,729

9,817

496,474

Price on 9/6/2016

(1)

32.66

0.6430

21.00

14,535,729

9,421

484,158

(2.5%)

31.84

0.6430

20.47

14,535,729

9,024

471,842

(5.0%)

31.03

0.6430

19.95

14,535,729

8,632

459,676

(7.5%)

30.21

0.6430

19.43

14,535,729

8,236

447,360

(10.0%)

29.39

0.6430

18.90

14,535,729

7,839

435,044

(12.5%)

28.58

0.6430

18.38

14,535,729

7,447

422,878

(15.0%)

27.76

0.6430

17.85

14,535,729

7,050

410,562

Aggregate Merger Consideration

The chart below illustrates the impact of various hypothetical COLB stock prices on the value of the per share merger consideration

and aggregate merger consideration.

Illustrative Impact of Hypothetical Columbia Stock Price

Note

Outside

the

15%

collar,

the

purchase

price

fixes

$24.15

$17.85,

respectively,

COLB

outperforms

(above

the

range)/underperforms

(below

the

range) the KBW Regional Bank Index by 15% or more. If the price fixes at $17.85, COLB can decide whether to fill with cash or increase the exchange ratio.

Note II: COLB and PCBK have termination rights should COLB stock drop below $26.13 (with PCBK’s right to reinstate by including per share cash consideration of

$1.05).

(1)

Date when the collar was established.

Rank

Institution (ST)

Number of

Branches

Deposits in

Market

($mm)

Market

(%)

U.S. Bancorp (MN)

195

14,838

20.8

Wells Fargo & Co. (CA)

123

11,901

16.7

Bank of America Corp. (NC)

9,506

13.4

Umpqua Holdings Corp. (OR)

102

7,438

10.5

JPMorgan Chase & Co. (NY)

113

6,099

8.6

KeyCorp (OH)

4,108

5.8

Pro Forma

4,070

5.7

Columbia Banking System Inc. (WA)

2,730

3.8

Cascade Bancorp (OR)

1,889

2.7

Washington Federal Inc. (WA)

1,821

2.6

Banner Corp. (WA)

1,686

2.4

BNP Paribas USA Inc. (NY)

1,558

2.2

Pacific Continental Corp. (OR)

1,340

1.9

Totals (1-12)

871

64,915

91.2

Totals (1-46)

1,004

71,189

100.0

Rank

Institution (ST)

Number of

Branches

Deposits in

Market

($mm)

Market

(%)

Bank of America Corp. (NC)

171

30,395

21.3

Wells Fargo & Co. (CA)

158

17,582

12.3

JPMorgan Chase & Co. (NY)

204

15,192

10.6

U.S. Bancorp (MN)

185

15,029

10.5

KeyCorp (OH)

155

9,903

6.9

Washington Federal Inc. (WA)

5,224

3.7

Pro Forma

5,072

3.6

Umpqua Holdings Corp. (OR)

4,896

3.4

Columbia Banking System Inc. (WA)

4,386

3.1

Banner Corp. (WA)

4,227

3.0

W.T.B. Financial Corp. (WA)

3,812

2.7

Pacific Continental Corp. (OR)

686

0.5

Totals (1-10)

1,242

110,644

77.3

Totals (1-78)

1,750

143,052

100.0

Washington

Oregon

(1)

Includes Idaho, Oregon and Washington.

(2)

PCBK branches excludes branch in Bellevue that is expected to be closed in January 2017.

Source: SNL Financial. Deposit market share data pro forma per FDIC S.O.D. as of 6/30/2016.

Northwest

(1)

Rank

Institution (ST)

Number of

Branches

Deposits in

Market

($mm)

Market

(%)

Bank of America Corp. (NC )

225

40,648

17.2

Wells Fargo & Co. (CA )

367

34,356

14.5

U.S. Bancorp (MN )

477

33,796

14.3

JPMorgan Chase & Co. (NY )

337

21,965

9.3

KeyCorp (OH )

255

15,466

6.5

Umpqua Holdings Corp. (OR )

214

12,751

5.4

Pro Forma

157

9,678

4.1

Washington Federal Inc. (WA )

155

7,763

3.3

Columbia Banking System Inc. (WA )

143

7,651

3.2

Banner Corp. (WA )

148

6,272

2.7

W.T.B. Financial Corp. (WA )

4,494

1.9

Mitsubishi UFJ Financial Group Inc. (- )

3,254

1.4

Heritage Financial Corp. (WA )

3,176

1.3

HomeStreet Inc. (WA )

3,094

1.3

Cascade Bancorp (OR )

2,662

1.1

Zions Bancorp. (UT )

2,421

1.0

Pacific Continental Corp. (OR )

2,026

0.9

BNP Paribas USA Inc. (NY )

1,936

0.8

Glacier Bancorp Inc. (MT )

1,621

0.7

Yakima Federal S&L Assc. (WA )

1,354

0.6

Peoples Bancorp (WA )

1,328

0.6

Opus Bank (CA )

1,318

0.6

East West Bancorp Inc. (CA )

1,242

0.5

Cashmere Valley Bank (WA )

1,208

0.5

D.L. Evans Bancorp (ID )

1,023

0.4

Olympic Bancorp Inc. (WA )

983

0.4

Riverview Bancorp Inc. (WA )

928

0.4

HSBC Holdings Plc (- )

855

0.4

Bank of Commerce (ID )

791

0.3

Skagit Bancorp Inc. (WA )

735

0.3

Pacific Financial Corp. (WA )

734

0.3

Totals (1-30)

2,851

217,852

92.2

Totals (1-114)

3,253

236,169

100.0

Combined Deposit Market Share in Northwest

(2)

Source: SNL Financial as of 9/30/2016.

Note: All dollars in thousands.

Pro Forma Loan and Deposit Composition

Gross Loans (Incl. HFS): $6,263,118

Gross Loans (Incl. HFS): $1,806,736

Gross Loans (Incl. HFS): $8,069,854

Loan Composition:

Columbia Banking System, Inc.

Pacific Continental Corporation

Pro Forma Company

Yield on Loans: 4.93%

Yield on Loans: 5.11%

Deposit Composition:

Columbia Banking System, Inc.

Pacific Continental Corporation

Pro Forma Company

Total Deposits: $8,057,816

Total Deposits: $2,162,633

Total Deposits: $10,220,449

Cost of Deposits: 0.04%

Cost of Deposits: 0.22%

C&D

C&I

42%

Res. RE

Multifamily

Owner-

occupied

CRE

20%

Nonowner-

occupied

CRE

21%

Consumer

& Other

C&D

10%

C&I

35%

Res. RE

Multifamily

Owner-

occupied

CRE

24%

Nonowner-

occupied

CRE

24%

Consumer

& Other

C&D

C&I

40%

Res. RE

Multifamily

Owner-

occupied

CRE

21%

Nonowner-

occupied

CRE

22%

Consumer

& Other

DDA

49%

NOW &

Other

MMDA &

Sav.

44%

Retail Time

Jumbo

Time

DDA

42%

NOW &

Other

12%

MMDA &

Sav.

38%

Retail Time

Jumbo

Time

DDA

47%

NOW &

Other

MMDA &

Sav.

43%

Retail Time

Jumbo

Time

Mount Rainier Bank (July 2007)

$266 million

Town Center Bank (July 2007)

$166 million

FDIC-assisted acquisitions:

•

Columbia River Bank (January 2010)

$913 million

•

American Marine Bank (January 2010)

$308 million

•

Summit Bank (May 2011)

$131 million

•

First Heritage Bank (May 2011)

$165 million

•

Bank of Whitman (August 2011)

$438 million

West Coast Bancorp (April 2013)

$ 2.6 billion

Intermountain Community Bancorp (November 2014)

$964 million

Assets

Nine

Acquisitions

the

last

Years

COLB’s M&A Criteria

•

Meets financial hurdles consistent with shareholder expectations

TBV Earnback, Earnings Accretion and IRR

•

Expands geographic footprint

•

Culturally compatible

•

Strong core deposits

Seasoned Acquirer with Proven Integration Track Record

Columbia’s

Growth

Total

Assets

2006

2016

Intermountain

Community

Bancorp

West Coast

Bancorp

Bank of Whitman*

First Heritage*

Summit*

Columbia River*

American Marine*

Town Center

Mount Rainier

*FDIC Assisted

Acquisition

$2,553

$3,179

$3,097

$3,201

$4,256

$4,786

$4,906

$7,162

$8,579

$8,952

$9,587

$12,126

$2,500

$5,000

$7,500

$10,000

$12,500

2006

2007

2008

2009

2010

2011

2012

2013

2014

2015

Q3-16

Pro

Forma

Acquisitions

$ in Millions

Pacific

Continental

Corporation

10 Year CAGR

(1)

= 14%

(1)

CAGR calculation from 9/30/2006 to 9/30/2016.

Shareholders are urged to carefully review and consider each of Columbia’s and Pacific Continental’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.

connection

with

the

proposed

transaction,

Columbia

will

file

with

the

SEC

Registration

Statement

Form

S-4

that

will

include

Joint

Proxy

Statement of Columbia and PCBK and a Prospectus of Columbia, as well as other relevant documents concerning the proposed transaction.

Shareholders of Columbia and PCBK are urged to carefully read the Registration Statement and the Joint Proxy Statement/Prospectus regarding the

transaction in their entirety when they become available and any other relevant documents filed with the SEC, as well as any amendments or

supplements

those

documents,

because

they

will

contain

important

information.

definitive

Joint

Proxy

Statement/Prospectus

will

sent

the shareholders of each institution seeking any required shareholder approvals. The Joint Proxy Statement/Prospectus and other relevant

materials (when they become available) filed with the SEC may be obtained free of charge at the SEC’s website at http://www.sec.gov. Both

Columbia and PCBK shareholders are urged to read the Joint Proxy Statement/Prospectus and the other relevant materials before voting on the

transaction.

Investors

will

also

able

obtain

these

documents,

free

charge,

from

PCBK

accessing

its

website

www.therightbank.com

under

the

link

“Investor

Relations”

from

Columbia

www.columbiabank.com

under

the

tab

“About

Us”

and

then

under

the

heading

“Investor

Relations.”

Copies can also be obtained, free of charge, by directing a written request to Columbia Banking System, Inc., Attention: Corporate Secretary, 1301 A

Street, Suite 800, Tacoma, Washington 98401-2156 or to Pacific Continental Corporation, Attention: Corporate Secretary 111 West Seventh Avenue,

P.O. Box 10727, Eugene, Oregon 97440-2727.

PCBK and Columbia and their directors and executive officers and certain other persons may be deemed to be participants in the solicitation of

proxies from the shareholders of Columbia and PCBK in connection with the merger. Information about the directors and executive officers of

Columbia and their ownership of Columbia common stock is set forth in the proxy statement for Columbia’s 2016 annual meeting of shareholders,

as filed with the SEC on a Schedule 14A on March 16, 2016. Information about the directors and executive officers of PCBK and their ownership of

PCBK common stock is set forth in the proxy statement for PCBK’s 2016 annual meeting of shareholders, as filed with the SEC on a Schedule 14A on

March 15, 2016. Additional information regarding the interests of those participants and other persons who may be deemed participants in the

transaction may be obtained by reading the Joint Proxy Statement/Prospectus regarding the merger when it becomes available. Free copies of

this document may be obtained as described in the preceding paragraph.

Additional Information

Melanie J. Dressel

President & Chief Executive Officer

253-305-1911; mdressel@columbiabank.com

Clint E. Stein

EVP & Chief Financial Officer

253-593-8304; cstein@columbiabank.com

Roger S. Busse

President & Chief Executive Officer

541-686-8685; roger.busse@therightbank.com

Columbia Banking System (COLB) 8-KForm of Voting Andnon-competition Agreement