COLB / Columbia Banking System, Inc. - SEC फाइलिंग, वार्षिक रिपोर्ट, प्रॉक्सी स्टेटमेंट

कोलंबिया बैंकिंग सिस्टम, इंक.
US ˙ NasdaqGS ˙ US1972361026

मूलभूत आँकड़े
LEI 549300O1LD28IAZM0Y68
CIK 887343
SEC Filings
All companies that sell securities in the United States must register with the Securities and Exchange Commission (SEC) and file reports on a regular basis. These reports include company annual reports (10K, 10Q), news updates (8K), investor presentations (found in 8Ks), insider trades (form 4), ownership reports (13D, and 13G), and reports related to the specific securities sold, such as registration statements and prospectus. This page shows recent SEC filings related to Columbia Banking System, Inc.
SEC Filings (Chronological Order)
यह पृष्ठ SEC फाइलिंग की एक पूरी, कालानुक्रमिक सूची प्रदान करता है, ओनरशिप फाइलिंग को छोड़कर, जो हम अन्यत्र प्रदान करते हैं।
September 3, 2025 8-K/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K/A CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report: September 2, 2025 (Date of earliest event reported) Columbia Bank

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K/A CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report: September 2, 2025 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation

September 3, 2025 EX-99.2

UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION

UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION The following unaudited pro forma condensed combined financial information and the accompanying notes (the “pro forma financial information”) are presented to illustrate the effects of the accounting for the mergers.

September 2, 2025 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): September 2, 2025 Columbia Bankin

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): September 2, 2025 Columbia Banking System, Inc. (Exact name of registrant as specified in its charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation) (

September 2, 2025 S-8

As filed with the Securities and Exchange Commission on September 2, 2025

S-8 As filed with the Securities and Exchange Commission on September 2, 2025 Registration No.

September 2, 2025 EX-99.1

Columbia Banking System Completes Acquisition of Pacific Premier Bancorp and Unifies Columbia Brand

EX-99.1 Exhibit 99.1 Columbia Banking System Completes Acquisition of Pacific Premier Bancorp and Unifies Columbia Brand Acquisition accelerates Southern California expansion Columbia Bank unveils new brand, introduces name change to customers TACOMA, Wash., (September 2, 2025)—Columbia Banking System, Inc. (“Columbia”) (Nasdaq: COLB), the parent company of Columbia Bank, and Pacific Premier Banco

September 2, 2025 EX-10.1

CONSULTING AGREEMENT

EX-10.1 Exhibit 10.1 EXECUTION COPY CONSULTING AGREEMENT This Consulting Agreement (“Agreement”) is made and entered into on September 2, 2025 by and between Columbia Banking System, Inc., a Washington corporation (“CBSI”), Columbia Bank, an Oregon state-chartered commercial bank and wholly owned subsidiary of CBSI (together with CBSI, the “Company”) and Steven R. Gardner (“Consultant”). WHEREAS,

September 2, 2025 EX-24.1

POWER OF ATTORNEY

EX-24.1 Exhibit 24.1 POWER OF ATTORNEY KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Clint E. Stein and Ronald L. Farnsworth and each of them, his or her true and lawful attorneys-in-fact and agents, with full power to act separately and full power of substitution and resubstitution, for him or her and in his or her name, place and stea

September 2, 2025 EX-FILING FEES

CALCULATION OF FILING FEE TABLE FORM S-8 COLUMBIA BANKING SYSTEM, INC. (Exact Name of Registrant as Specified in Its Charter) Table 1: Newly Registered Securities

Exhibit 107 CALCULATION OF FILING FEE TABLE FORM S-8 COLUMBIA BANKING SYSTEM, INC.

August 29, 2025 EX-99.1

# # #

Columbia Banking System Announces Date of Third Quarter 2025 Earnings Release and Conference Call TACOMA, Wash.

August 29, 2025 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 and Exchange Act of 1934 Date of Report: August 29, 2025 (Date of earliest event reported) Columbia Bank

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 and Exchange Act of 1934 Date of Report: August 29, 2025 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation

August 15, 2025 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 and Exchange Act of 1934 Date of Report: August 15, 2025 (Date of earliest event reported) Columbia Bank

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 and Exchange Act of 1934 Date of Report: August 15, 2025 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation

August 15, 2025 EX-99.1

# # #

Columbia Banking System Announces $0.36 Per Common Share Dividend TACOMA, Wash., August 15, 2025 – Columbia Banking System, Inc. (“Columbia” Nasdaq: COLB), parent company of Columbia Bank,1 today announced its Board of Directors has approved a quarterly cash dividend in the amount of $0.36 per common share, payable September 15, 2025, to shareholders of record as of August 29, 2025. About Columbia

August 6, 2025 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ Quarterly Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the quarterly period ended: June 30, 2025 or

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ Quarterly Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the quarterly period ended: June 30, 2025 or ☐ Transition Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the transition period from to . Commission File Number: 000-20288 COLUMBIA BANKING S

August 6, 2025 EX-99.1

Columbia Banking System and Pacific Premier Bancorp Announce Regulatory Approvals and Anticipated Merger Closing Date

Columbia Banking System and Pacific Premier Bancorp Announce Regulatory Approvals and Anticipated Merger Closing Date TACOMA, Wash.

August 6, 2025 EX-3.2

Amended and Restated Bylaws

EXHIBIT 3.2 AMENDED AND RESTATED BYLAWS OF COLUMBIA BANKING SYSTEM, INC. Table of Contents ARTICLE 1 Meetings of Shareholders 4 SECTION 1.1 – Shareholder Meetings. 4 SECTION 1.2 – Annual Meeting. 4 SECTION 1.3 – Special Meetings. 4 SECTION 1.4 – Nominations and Business at Annual and Special Meetings. 4 SECTION 1.5 – Notice. 5 SECTION 1.6 – Quorum; Vote Required. 5 SECTION 1.7 – Adjournment. 6 SEC

August 6, 2025 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: August 6, 2025 (Date of earliest event reported) Columbia Banking S

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: August 6, 2025 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation or Or

July 24, 2025 8-K

Regulation FD Disclosure, Financial Statements and Exhibits, Results of Operations and Financial Condition

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 and Exchange Act of 1934 Date of Report: July 24, 2025 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation or

July 24, 2025 EX-99.1

COLUMBIA BANKING SYSTEM, INC. REPORTS SECOND QUARTER 2025 RESULTS

EXHIBIT 99.1 00 COLUMBIA BANKING SYSTEM, INC. REPORTS SECOND QUARTER 2025 RESULTS $152 million $160 million $0.73 $0.76 Net income Operating net income 1 Earnings per common share - diluted Operating earnings per common share - diluted 1 0 CEO Commentary “Our second quarter results demonstrate our focus on profitability and balance sheet optimization,” said Clint Stein, President and CEO. “Commerc

July 24, 2025 EX-99.2

2nd Quarter 2025 Earnings Presentation July 24, 2025 Disclaimer FORWARD-LOOKING STATEMENTS This communication may contain certain forward-looking statements, including, but not limited to, certain plans, expectations, goals, projections, and statemen

colbq22025earningspresen 2nd Quarter 2025 Earnings Presentation July 24, 2025 Disclaimer FORWARD-LOOKING STATEMENTS This communication may contain certain forward-looking statements, including, but not limited to, certain plans, expectations, goals, projections, and statements about the benefits of the proposed business combination transaction between Columbia Banking System, Inc.

July 22, 2025 EX-99.1

Columbia Banking System and Pacific Premier Bancorp Announce Shareholder and Stockholder Approval for Proposed Acquisition

Columbia Banking System and Pacific Premier Bancorp Announce Shareholder and Stockholder Approval for Proposed Acquisition TACOMA, Wash.

July 22, 2025 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 and Exchange Act of 1934 Date of Report: July 21, 2025 (Date of earliest event reported) Columbia Bankin

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 and Exchange Act of 1934 Date of Report: July 21, 2025 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation or

July 11, 2025 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): July 11, 2025 COLUMBIA BANKING SY

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): July 11, 2025 COLUMBIA BANKING SYSTEM, INC. (Exact name of registrant as specified in its charter) Washington 000-20288 91-1422237 (State or other jurisdiction of incorporation) (Comm

July 11, 2025 425

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): July 11, 2025 COLUMBIA BANKING SY

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): July 11, 2025 COLUMBIA BANKING SYSTEM, INC. (Exact name of registrant as specified in its charter) Washington 000-20288 91-1422237 (State or other jurisdiction of incorporation) (Comm

June 30, 2025 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 and Exchange Act of 1934 Date of Report: June 30, 2025 (Date of earliest event reported) Columbia Bankin

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 and Exchange Act of 1934 Date of Report: June 30, 2025 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation or

June 30, 2025 EX-99.1

# # #

Columbia Banking System Announces Date of Second Quarter 2025 Earnings Release and Conference Call TACOMA, Wash.

June 27, 2025 11-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 11-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 11-K (Mark One) x ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended DECEMBER 31, 2024 OR [ ] TRANSITION REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to . Commission File Number.....000-20288 A. Full title of th

June 16, 2025 424B3

To the Shareholders of Columbia Banking System, Inc. and the Stockholders of Pacific Premier Bancorp, Inc. MERGER PROPOSED—YOUR VOTE IS VERY IMPORTANT

Table of Contents Filed Pursuant to Rule 424(b)(3) Registration Statement No. 333-287607 To the Shareholders of Columbia Banking System, Inc. and the Stockholders of Pacific Premier Bancorp, Inc. MERGER PROPOSED—YOUR VOTE IS VERY IMPORTANT On behalf of the boards of directors of Columbia Banking System, Inc. (“Columbia”) and Pacific Premier Bancorp, Inc. (“Pacific Premier”), we are pleased to encl

June 13, 2025 EX-99.4

Consent of Keefe, Bruyette & Woods, Inc.

Exhibit 99.4 CONSENT OF KEEFE, BRUYETTE & WOODS, INC. We hereby consent to the inclusion of our opinion letter to the Board of Directors of Pacific Premier Bancorp, Inc. (“Pacific Premier”), as Annex C to the joint proxy statement/prospectus which forms a part of Amendment No. 1 to the registration statement on Form S-4 (Registration No. 333-287607) filed on the date hereof (the “Amended Registrat

June 13, 2025 S-4/A

As filed with the Securities and Exchange Commission on June 13, 2025

Table of Contents As filed with the Securities and Exchange Commission on June 13, 2025 Registration No.

June 13, 2025 EX-99.3

Consent of Piper Sandler & Co.

Exhibit 99.3 1251 AVENUE OF THE AMERICAS, 6TH FLOOR NEW YORK, NY 10020 P 212 466-7800 | TF 800 635-6851 Piper Sandler & Co. Since 1885. Member SIPC and NYSE. CONSENT OF PIPER SANDLER & CO. We hereby consent to the inclusion of our opinion letter to the Board of Directors of Columbia Banking System, Inc. (the “Company”) as an Annex to the Joint Proxy Statement/Prospectus relating to the proposed me

June 13, 2025 EX-99.2

Form of Proxy of Pacific Premier Bancorp, Inc.

EX-99.2 Exhibit 99.2 SCAN TO VIEW MATERIALS & VOTE VOTE BY INTERNET—www.proxyvote.com or scan the QR Barcode above PACIFIC PREMIER BANCORP, INC. Before the Meeting – Go to www.proxyvote.com or scan the QR Barcode above ATTN: CORPORATE SECRETARY 17901 VON KARMAN AVE Use the Internet to transmit your voting instructions and for electronic delivery of SUITE 1200 information. Vote by 11:59 p.m. ET on

June 13, 2025 CORRESP

[Letterhead of Columbia Banking System, Inc.]

CORRESP 1 filename1.htm [Letterhead of Columbia Banking System, Inc.] June 13, 2025 Via Edgar U.S. Securities and Exchange Commission Division of Corporation Finance 100 F Street, NE Washington, D.C. 20549 Attn: Aisha Adegbuyi Re: Columbia Banking System, Inc. Registration Statement on Form S-4 (File No. 333-287607) Ladies and Gentlemen: Pursuant to the requirements of Rule 461 under the Securitie

June 13, 2025 EX-99.1

Form of Proxy of Columbia Banking System, Inc.

Exhibit 99.1 SCAN TO COLUMBIA BANKING SYSTEM, INC. VIEW MATERIALS & VOTE w C/O BROADRIDGE VOTE BY INTERNET P.O. BOX 1342 Before The Meeting - Go to www.proxyvote.com or scan the QR Barcode above BRENTWOOD, NY 11717 Use the Internet to transmit your voting instructions and for electronic delivery of information. Vote by 8:59 p.m. Pacific Time on July 20, 2025 for shares held directly and by 8:59 p.

May 28, 2025 S-4

As filed with the Securities and Exchange Commission on May 27, 2025

Table of Contents As filed with the Securities and Exchange Commission on May 27, 2025 Registration No.

May 28, 2025 EX-99.5

Consent of Steven R. Gardner to be named as director.

EX-99.5 Exhibit 99.5 CONSENT OF PROSPECTIVE DIRECTOR In accordance with Rule 438 promulgated under the Securities Act of 1933, as amended, I hereby consent to my being named in this Registration Statement on Form S-4, to which this consent is an exhibit, filed by Columbia Banking System, Inc., a Washington corporation (“Columbia”), with the Securities and Exchange Commission, and all amendments (i

May 28, 2025 EX-FILING FEES

Filing Fee Table.

Calculation of Filing Fee Tables S-4 COLUMBIA BANKING SYSTEM, INC. Table 1: Newly Registered and Carry Forward Securities Security Type Security Class Title Fee Calculation or Carry Forward Rule Amount Registered Proposed Maximum Offering Price Per Unit Maximum Aggregate Offering Price Fee Rate Amount of Registration Fee Carry Forward Form Type Carry Forward File Number Carry Forward Initial Effec

May 28, 2025 EX-99.4

Consent of Keefe, Bruyette & Woods, Inc.

EX-99.4 Exhibit 99.4 CONSENT OF KEEFE, BRUYETTE & WOODS, INC. We hereby consent to the inclusion of our opinion letter to the Board of Directors of Pacific Premier Bancorp, Inc. (“Pacific Premier”), as Annex C to the joint proxy statement/prospectus which forms a part of the registration statement on Form S-4 filed on the date hereof (the “Registration Statement”) relating to the proposed merger o

May 28, 2025 EX-99.3

Consent of Piper Sandler & Co.

EX-99.3 Exhibit 99.3 1251 AVENUE OF THE AMERICAS, 6TH FLOOR NEW YORK, NY 10020 P 212 466-7800 | TF 800 635-6851 Piper Sandler & Co. Since 1885. Member SIPC and NYSE. CONSENT OF PIPER SANDLER & CO. We hereby consent to the inclusion of our opinion letter to the Board of Directors of Columbia Banking System, Inc. (the “Company”) as an Annex to the Joint Proxy Statement/Prospectus relating to the pro

May 16, 2025 8-K

Financial Statements and Exhibits, Other Events

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 and Exchange Act of 1934 Date of Report: May 16, 2025 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation or

May 16, 2025 EX-99.1

# # #

Columbia Banking System Announces $0.36 Per Common Share Dividend TACOMA, Wash., May 16, 2025 – Columbia Banking System, Inc. (“Columbia” Nasdaq: COLB), parent company of Umpqua Bank, today announced its Board of Directors has approved a quarterly cash dividend in the amount of $0.36 per common share, payable June 16, 2025, to shareholders of record as of May 30, 2025. About Columbia Columbia (Nas

May 15, 2025 8-K

Submission of Matters to a Vote of Security Holders

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 and Exchange Act of 1934 Date of Report: May 15, 2025 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation or

May 6, 2025 425

Filed by: Columbia Banking System, Inc.

Filed by: Columbia Banking System, Inc. Pursuant to Rule 425 under the Securities Act of 1933 and deemed filed pursuant to Rule 14a-12 of the Securities Exchange Act of 1934 Subject Company: Pacific Premier Bancorp, Inc. Commission File No.: 000-22193 This filing relates to the proposed transaction between Columbia Banking System, Inc. (“Columbia”) and Pacific Premier Bancorp, Inc. (“Pacific Premi

May 6, 2025 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ Quarterly Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the quarterly period ended: March 31, 2025 or

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ Quarterly Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the quarterly period ended: March 31, 2025 or ☐ Transition Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the transition period from to . Commission File Number: 000-20288 COLUMBIA BANKING

May 5, 2025 8-K

Regulation FD Disclosure, Financial Statements and Exhibits

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 and Exchange Act of 1934 Date of Report: May 5, 2025 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation or O

May 5, 2025 EX-99.1

May 2025 Investor Presentation Disclaimer FORWARD-LOOKING STATEMENTS This communication may contain certain forward-looking statements, including, but not limited to, certain plans, expectations, goals, projections, and statements about the benefits

May 2025 Investor Presentation Disclaimer FORWARD-LOOKING STATEMENTS This communication may contain certain forward-looking statements, including, but not limited to, certain plans, expectations, goals, projections, and statements about the benefits of the proposed business combination transaction between Columbia Banking System, Inc.

April 25, 2025 8-K

Current Report

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): April 23, 2025 COLUMBIA BANKING SYSTEM, INC. (Exact name of registrant as specified in its charter) Washington 000-20288 91-1422237 (State or other jurisdiction of incorporation) (Com

April 25, 2025 425

2

Columbia Banking System, Inc. Pursuant to Rule 425 under the Securities Act of 1933 and deemed filed pursuant to Rule 14a-12 of the Securities Exchange Act of 1934 Subject Company: Pacific Premier Bancorp, Inc. Commission File No.: 000-22193 This filing relates to the proposed transaction between Columbia Banking System, Inc. (“Columbia”) and Pacific Premier Bancorp, Inc. (“Pacific Premier”) pursu

April 25, 2025 425

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): April 23, 2025 COLUMBIA BANKING S

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): April 23, 2025 COLUMBIA BANKING SYSTEM, INC. (Exact name of registrant as specified in its charter) Washington 000-20288 91-1422237 (State or other jurisdiction of incorporation) (Com

April 25, 2025 EX-2.1

Agreement and Plan of Merger, dated as of April 23, 2025, by and among the Company, Pacific Premier, and Balboa Merger Sub, Inc.

Exhibit 2.1 AGREEMENT AND PLAN OF MERGER by and among COLUMBIA BANKING SYSTEM, INC., PACIFIC PREMIER BANCORP, INC., and BALBOA MERGER SUB, INC. Dated as of April 23, 2025 TABLE OF CONTENTS Page ARTICLE 1 MERGERS 2 1.1 The Merger 2 1.2 Closing 2 1.3 Effective Time 2 1.4 Effects of the Merger 2 1.5 Conversion of Stock 2 1.6 Treatment of Company Equity Awards 3 1.7 Certificate of Incorporation and By

April 24, 2025 425

Text

425 Filed by: Columbia Banking System, Inc. Pursuant to Rule 425 under the Securities Act of 1933 and deemed filed pursuant to Rule 14a-12 of the Securities Exchange Act of 1934 Subject Company: Pacific Premier Bancorp, Inc. Commission File No.: 000-22193 This filing relates to the proposed transaction between Columbia Banking System, Inc. (“Columbia”) and Pacific Premier Bancorp, Inc. (“Pacific P

April 24, 2025 425

Page 1 of 4

425 Filed by: Columbia Banking System, Inc. Pursuant to Rule 425 under the Securities Act of 1933 and deemed filed pursuant to Rule 14a-12 of the Securities Exchange Act of 1934 Subject Company: Pacific Premier Bancorp, Inc. Commission File No.: 000-22193 This filing relates to the proposed transaction between Columbia Banking System, Inc. (“Columbia”) and Pacific Premier Bancorp, Inc. (“Pacific P

April 24, 2025 425

Page 1 of 7

425 Filed by: Columbia Banking System, Inc. Pursuant to Rule 425 under the Securities Act of 1933 and deemed filed pursuant to Rule 14a-12 of the Securities Exchange Act of 1934 Subject Company: Pacific Premier Bancorp, Inc. Commission File No.: 000-22193 This filing relates to the proposed transaction between Columbia Banking System, Inc. (“Columbia”) and Pacific Premier Bancorp, Inc. (“Pacific P

April 24, 2025 425

Filed by: Columbia Banking System, Inc.

425 Filed by: Columbia Banking System, Inc. Pursuant to Rule 425 under the Securities Act of 1933 and deemed filed pursuant to Rule 14a-12 of the Securities Exchange Act of 1934 Subject Company: Pacific Premier Bancorp, Inc. Commission File No.: 000-22193 This filing relates to the proposed transaction between Columbia Banking System, Inc. (“Columbia”) and Pacific Premier Bancorp, Inc. (“Pacific P

April 24, 2025 425

Filed by: Columbia Banking System, Inc.

425 Filed by: Columbia Banking System, Inc. Pursuant to Rule 425 under the Securities Act of 1933 and deemed filed pursuant to Rule 14a-12 of the Securities Exchange Act of 1934 Subject Company: Pacific Premier Bancorp, Inc. Commission File No.: 000-22193 This filing relates to the proposed transaction between Columbia Banking System, Inc. (“Columbia”) and Pacific Premier Bancorp, Inc. (“Pacific P

April 23, 2025 425

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): April 23, 2025 COLUMBIA BANKING S

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): April 23, 2025 COLUMBIA BANKING SYSTEM, INC. (Exact name of registrant as specified in its charter) Washington 000-20288 91-1422237 (State or other jurisdiction of incorporation) (Com

April 23, 2025 EX-99.1

COLUMBIA BANKING SYSTEM, INC. REPORTS FIRST QUARTER 2025 RESULTS

EXHIBIT 99.1 00 COLUMBIA BANKING SYSTEM, INC. REPORTS FIRST QUARTER 2025 RESULTS $87 million $140 million $0.41 $0.67 Net income Operating net income 1 Earnings per diluted common share Operating earnings per diluted common share 1 0 CEO Commentary “Our consistent, repeatable performance in 2024 carried through to the first quarter of 2025,” said Clint Stein, President and CEO. “Although the globa

April 23, 2025 EX-99.2

Disclaimers FORWARD-LOOKING STATEMENTS This communication may contain certain forward-looking statements, including, but not limited to, certain plans, expectations, goals, projections, and statements about the benefits of the proposed business combi

Exhibit 99.2 Columbia Banking System’s Strategic Acquisition of Pacific Premier Bancorp, Inc. Expanding the Premier Business Bank in the West April 23, 2025 Disclaimers FORWARD-LOOKING STATEMENTS This communication may contain certain forward-looking statements, including, but not limited to, certain plans, expectations, goals, projections, and statements about the benefits of the proposed busines

April 23, 2025 EX-99.2

1st Quarter 2025 Earnings Presentation April 23, 2025 Disclaimer FORWARD-LOOKING STATEMENTS This presentation includes forward-looking statements within the meaning of the "Safe-Harbor" provisions of the Private Securities Litigation Reform Act of 19

1st Quarter 2025 Earnings Presentation April 23, 2025 Disclaimer FORWARD-LOOKING STATEMENTS This presentation includes forward-looking statements within the meaning of the "Safe-Harbor" provisions of the Private Securities Litigation Reform Act of 1995, which management believes are a benefit to shareholders.

April 23, 2025 EX-99.1

Columbia Banking System to Acquire Pacific Premier

Exhibit 99.1 Columbia Banking System to Acquire Pacific Premier Bancorp, Expanding the Premier Business Bank in the West Natural Combination of the Western Region’s Leading Business Banks Builds Market Presence and Drives Financial Performance TACOMA, Wash. and IRVINE, Cal., April 23, 2025/PRNewswire/ — Columbia Banking System, Inc. (“Columbia”) (Nasdaq: COLB), the parent company of Umpqua Bank, a

April 23, 2025 8-K

Regulation FD Disclosure, Financial Statements and Exhibits, Results of Operations and Financial Condition

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 and Exchange Act of 1934 Date of Report: April 23, 2025 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation o

April 23, 2025 8-K

Regulation FD Disclosure, Other Events

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): April 23, 2025 COLUMBIA BANKING SYSTEM, INC. (Exact name of registrant as specified in its charter) Washington 000-20288 91-1422237 (State or other jurisdiction of incorporation) (Com

April 3, 2025 DEF 14A

DEF 14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 14A SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No.

April 3, 2025 DEFA14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 14A SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No.)

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 14A SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No.

April 2, 2025 8-K

Regulation FD Disclosure, Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Financial Statements and Exhibits

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 and Exchange Act of 1934 Date of Report: March 30, 2025 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation o

April 2, 2025 EX-99.1

# # #

Columbia Banking System Announces Board Chair Transition TACOMA, Wash., April 2, 2025 – Columbia Banking System, Inc. (“Columbia” Nasdaq: COLB) announced a leadership transition today reflecting the completion of the integration following Columbia’s previously announced merger with Umpqua Holdings Corporation on February 28, 2023, which combined two premier banks in the Northwest to create one of

March 31, 2025 11-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 11-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 11-K (Mark One) x ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended DECEMBER 31, 2024 OR [ ] TRANSITION REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to . Commission File Number.....000-20288 A. Full title of th

March 31, 2025 8-K

Regulation FD Disclosure, Financial Statements and Exhibits

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 and Exchange Act of 1934 Date of Report: March 31, 2025 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation o

March 31, 2025 EX-99.1

# # #

Columbia Banking System Announces Date of First Quarter 2025 Earnings Release and Conference Call TACOMA, Wash.

March 27, 2025 8-K

Regulation FD Disclosure

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 and Exchange Act of 1934 Date of Report: March 27, 2025 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation o

February 25, 2025 EX-10.82

Form of First Amendment to the Umpqua Bank Endorsement Method Split Dollar Agreement (includes the following insured individuals: Drew K. Anderson, Frank D. Namdar, Torran B. Nixon, and Andrew H. Ognall)

EXHIBIT 10.82 FIRST AMENDMENT TO THE UMPQUA BANK ENDORSEMENT METHOD SPLIT DOLLAR AGREEMENT (By and Between UMPQUA BANK and Named Executive) This First Amendment to the Umpqua Bank Endorsement Method Split Dollar Agreement (“Amendment”) hereby amends the prior Umpqua Bank Endorsement Method Split Dollar Agreement (“Agreement”), previously entered into on February 1, 2024, by and between UMPQUA BANK

February 25, 2025 EX-19.1

Columbia Banking System, Inc. Insider Trading Policy and Procedures, dated December 18, 2024

Exhibit 19.1 Insider Trading Policy STATEMENT OF COMPANY POLICY OF COLUMBIA BANKING SYSTEM, INC. The Need for an Insider Trading Policy The federal securities laws prohibit certain purchases or sales of securities while aware of material nonpublic information or certain disclosures of material nonpublic information to others who then trade on such information. Insider trading violations are pursue

February 25, 2025 EX-10.81

Columbia Banking System, Inc. Form of Participation Agreement (includes the following participants: Christopher Merrywell and Torran Nixon)

EXHIBIT 10.81 PARTICIPATION AGREEMENT Dear Re: Executive Participation Agreement Columbia Banking System, Inc. Executive Change in Control and Severance Plan Columbia Banking System, Inc. has established the Columbia Banking System, Inc. Executive Change in Control and Severance Plan. The Plan provides payments and benefits to certain eligible executives in the event of a Qualifying Termination. Y

February 25, 2025 EX-10.88

Third Amendment to the Umpqua Bank Endorsement Method Split Dollar Agreement, dated November 12, 2024, by and between Umpqua Bank and Lisa Dow

EXHIBIT 10.88 THIRD AMENDMENT TO THE UMPQUA BANK ENDORSEMENT METHOD SPLIT DOLLAR AGREEMENT (By and Between UMPQUA BANK and LISA DOW) This Third Amendment to the Umpqua Bank Endorsement Method Split Dollar Agreement (“Amendment”) hereby amends the prior Endorsement Method Split Dollar Agreement (“Original Agreement”, and as amended thereafter), previously entered into on July 1, 2013, by and betwee

February 25, 2025 EX-10.86

First Amendment to the Umpqua Bank Endorsement Method Split Dollar Agreement, dated December 31, 2024, by and between Umpqua Bank and Kumi Baruffi

EXHIBIT 10.86 FIRST AMENDMENT TO THE UMPQUA BANK ENDORSEMENT METHOD SPLIT DOLLAR AGREEMENT (By and Between UMPQUA BANK and KUMI BARUFFI) This First Amendment to the Umpqua Bank Endorsement Method Split Dollar Agreement (“Amendment”) hereby amends the prior Endorsement Method Split Dollar Agreement (“Original Agreement”), previously entered into on February 4th, 2016, by and between Columbia State

February 25, 2025 EX-10.89

First Amendment to the Umpqua Bank Endorsement Method Split Dollar Agreement, dated November 12, 2024, by and between Umpqua Bank and Lisa Dow

EXHIBIT 10.89 FIRST AMENDMENT TO THE UMPQUA BANK ENDORSEMENT METHOD SPLIT DOLLAR AGREEMENT (By and Between UMPQUA BANK and LISA DOW) This First Amendment to the Umpqua Bank Endorsement Method Split Dollar Agreement (“Amendment”) hereby amends the prior Endorsement Method Split Dollar Agreement (“Original Agreement”, and as amended thereafter), previously entered into on February 25th, 2019, by and

February 25, 2025 EX-10.85

First Amendment to the First Amended and Restated Umpqua Bank Joint Beneficiary Agreement, dated November 12, 2024, by and between Umpqua Bank and David Moore Devine

EXHIBIT 10.85 FIRST AMENDMENT TO THE FIRST AMENDED AND RESTATED UMPQUA BANK JOINT BENEFICIARY AGREEMENT (By and Between UMPQUA BANK and DAVID MOORE DEVINE) This First Amendment to the First Amended and Restated Umpqua Bank Joint Beneficiary Agreement (“Amendment”) hereby amends the prior First Amended and Restated Umpqua Bank Joint Beneficiary Agreement (“Agreement”), previously entered into on Fe

February 25, 2025 EX-10.87

Third Amendment to the Umpqua Bank Endorsement Method Split Dollar Agreement, dated December 31, 2024, by and between Umpqua Bank and Kumi Baruffi

EXHIBIT 10.87 THIRD AMENDMENT TO THE UMPQUA BANK ENDORSEMENT METHOD SPLIT DOLLAR AGREEMENT (By and Between UMPQUA BANK and KUMI BARUFFI) This Third Amendment to the Umpqua Bank Endorsement Method Split Dollar Agreement (“Amendment”) hereby amends the prior Endorsement Method Split Dollar Agreement (“Original Agreement”, and as amended thereafter), previously entered into on March 2nd, 2015, by and

February 25, 2025 EX-10.90

Third Amendment to the Umpqua Bank Joint Beneficiary Agreement, dated October 30, 2024, by and between Umpqua Bank and Clinton Stein

EXHIBIT 10.90 THIRD AMENDMENT TO THE UMPQUA BANK JOINT BENEFICIARY AGREEMENT (By and Between UMPQUA BANK and CLINTON STEIN) This Third Amendment to the Umpqua Bank Joint Beneficiary Agreement (“Amendment”) hereby amends the prior Joint Beneficiary Agreement (“Original Agreement”), previously entered into on November 11, 2011, by and between Columbia State Bank, which has since merged with and is n

February 25, 2025 EX-10.92

Umpqua Bank Endorsement Method Split Dollar Agreement, dated November 27, 2024, by and between Umpqua Bank and Ronald L. Farnsworth

UMPQ-PRIVATE EXHIBIT 10.92 UMPQUA BANK ENDORSEMENT METHOD SPLIT DOLLAR AGREEMENT (By and Between UMPQUA BANK and RONALD L. FARNSWORTH) Insurer/Policy: The Penn Mutual Life Insurance Company Policy #2940577 Protective Life Insurance Company Policy #85309444 Massachusetts Mutual Life Insurance Company Policy #39170838 The Lincoln National Life Insurance Company Policy #C0023726 Bank: UMPQUA BANK Ins

February 25, 2025 EX-21.1

Subsidiaries of Columbia Banking System, Inc. (incorporated by reference to Exhibit 21.1 of Columbia Banking System, Inc.’s Annual Report on Form 10-K filed on February 25, 2025).

Exhibit 21.1 Subsidiaries of Columbia Banking System, Inc. Name of Subsidiary State of Incorporation Other Names Under Which Business is Conducted Umpqua Bank Oregon Columbia Trust Company, Columbia Healthcare Banking, Columbia Private Bank, Columbia Wealth Advisors, Columbia Wealth Management, Umpqua Bank Home Lending, Umpqua Bank Equipment Leasing and Finance, Umpqua Bank Vendor Finance Financia

February 25, 2025 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended: December 31, 2024 OR ☐ TRANSITION REPORT PURSUANT TO S

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended: December 31, 2024 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 for the transition period from to . Commission file number: 000-20288 COLUMBIA BANKING SYSTE

February 25, 2025 EX-10.91

First Amendment to the First Amended and Restated Umpqua Bank Endorsement Method Split Dollar Agreement, dated October 30, 2024, by and between Umpqua Bank and Clinton Stein

EXHIBIT 10.91 FIRST AMENDMENT TO THE FIRST AMENDED AND RESTATED UMPQUA BANK ENDORSEMENT METHOD SPLIT DOLLAR AGREEMENT (By and Between UMPQUA BANK and CLINTON STEIN) This First Amendment to the First Amended and Restated Umpqua Bank Endorsement Method Split Dollar Agreement (“Amendment”) hereby amends the prior First Amended and Restated Endorsement Method Split Dollar Agreement (“Original Agreemen

February 25, 2025 EX-10.83

First Amendment to the First Amended and Restated Umpqua Bank Endorsement Method Split Dollar Agreement, dated October 18, 2024, by and between Umpqua Bank and Aaron Deer

EXHIBIT 10.83 FIRST AMENDMENT TO THE FIRST AMENDED AND RESTATED UMPQUA BANK ENDORSEMENT METHOD SPLIT DOLLAR AGREEMENT (By and Between UMPQUA BANK and AARON DEER) This First Amendment to the First Amended and Restated Umpqua Bank Endorsement Method Split Dollar Agreement (“Amendment”) hereby amends the prior First Amended and Restated Umpqua Bank Endorsement Method Split Dollar Agreement (“Agreemen

February 25, 2025 EX-3.2

Amended and Restated Bylaws of Columbia Banking System, Inc. (incorporated by reference to Exhibit 3.2 of Columbia Banking System, Inc.’s Annual Report on Form 10-K filed on February 25, 2025).

EXHIBIT 3.2 AMENDED AND RESTATED BYLAWS OF COLUMBIA BANKING SYSTEM, INC. Table of Contents ARTICLE 1 Meetings of Shareholders 4 SECTION 1.1 – Shareholder Meetings. 4 SECTION 1.2 – Annual Meeting. 4 SECTION 1.3 – Special Meetings. 4 SECTION 1.4 – Nominations and Business at Annual and Special Meetings. 4 SECTION 1.5 – Notice. 5 SECTION 1.6 – Quorum; Vote Required. 5 SECTION 1.7 – Adjournment. 6 SEC

February 25, 2025 EX-10.84

First Amendment to the First Amended and Restated Umpqua Bank Endorsement Method Split Dollar Agreement, dated October 28, 2024, by and between Umpqua Bank and Christopher Merrywell

EXHIBIT 10.84 FIRST AMENDMENT TO THE FIRST AMENDED AND RESTATED UMPQUA BANK ENDORSEMENT METHOD SPLIT DOLLAR AGREEMENT (By and Between UMPQUA BANK and CHRISTOPHER MERRYWELL) This First Amendment to the First Amended and Restated Umpqua Bank Endorsement Method Split Dollar Agreement (“Amendment”) hereby amends the prior First Amended and Restated Umpqua Bank Endorsement Method Split Dollar Agreement

February 25, 2025 EX-97.1

Columbia Banking System, Inc. Policy for the Recovery of Erroneously Awarded Incentive-based Compensation, dated October 22, 2024

EXHIBIT 97.1 COLUMBIA BANKING SYSTEM, INC. Policy for the Recovery of Erroneously Awarded Incentive-Based Compensation (Approved October 22, 2024) Background Columbia Banking System, Inc. the “Company” has adopted this policy (this “Policy”) to provide for the recovery or “clawback” of certain incentive compensation in the event of a Restatement (defined below). This Policy is intended to comply w

February 14, 2025 EX-99.1

# # #

Columbia Banking System Announces $0.36 Per Common Share Dividend TACOMA, Wash., February 14, 2025 – Columbia Banking System, Inc. (“Columbia” Nasdaq: COLB), parent company of Umpqua Bank, today announced its Board of Directors has approved a quarterly cash dividend in the amount of $0.36 per common share, payable March 17, 2025, to shareholders of record as of February 28, 2025. About Columbia Co

February 14, 2025 8-K

Financial Statements and Exhibits, Other Events

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 and Exchange Act of 1934 Date of Report: February 14, 2025 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporatio

January 23, 2025 8-K

Regulation FD Disclosure, Financial Statements and Exhibits, Results of Operations and Financial Condition

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 and Exchange Act of 1934 Date of Report: January 23, 2025 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation

January 23, 2025 EX-99.1

COLUMBIA BANKING SYSTEM, INC. REPORTS FOURTH QUARTER 2024 RESULTS

EXHIBIT 99.1 00 COLUMBIA BANKING SYSTEM, INC. REPORTS FOURTH QUARTER 2024 RESULTS $143 million $150 million $0.68 $0.71 Net income Operating net income 1 Earnings per diluted common share Operating earnings per diluted common share 1 0 CEO Commentary “Our fourth quarter and 2024 results reflect significant strides toward top-quartile performance,” said Clint Stein, President and CEO. “Our optimize

January 23, 2025 EX-99.2

4th Quarter 2024 Earnings Presentation January 23, 2025 Disclaimer FORWARD-LOOKING STATEMENTS This presentation includes forward-looking statements within the meaning of the "Safe-Harbor" provisions of the Private Securities Litigation Reform Act of

4th Quarter 2024 Earnings Presentation January 23, 2025 Disclaimer FORWARD-LOOKING STATEMENTS This presentation includes forward-looking statements within the meaning of the "Safe-Harbor" provisions of the Private Securities Litigation Reform Act of 1995, which management believes are a benefit to shareholders.

December 31, 2024 EX-99.1

# # #

Columbia Banking System Announces Date of Fourth Quarter 2024 Earnings Release and Conference Call TACOMA, Wash.

December 31, 2024 8-K

Regulation FD Disclosure, Financial Statements and Exhibits

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 and Exchange Act of 1934 Date of Report: December 31, 2024 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporatio

December 20, 2024 EX-FILING FEES

Filing Fee Table

Exhibit 107 Calculation of Filing Fee Tables Form S-3 (Form Type) COLUMBIA BANKING SYSTEM, INC (Exact Name of Registrant as Specified in its Charter) Table 1: Newly Registered and Carry Forward Securities Security Type Security Class Title Fee Calculation or Carry Forward Rule Amount Registered Proposed Maximum Offering Price Per Unit Maximum Aggregate Offering Price Fee Rate Amount of Registratio

December 20, 2024 S-3ASR

As filed with the Securities and Exchange Commission on December 20, 2024

As filed with the Securities and Exchange Commission on December 20, 2024 Registration No.

November 15, 2024 8-K

Financial Statements and Exhibits, Other Events

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 and Exchange Act of 1934 Date of Report: November 15, 2024 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporatio

November 15, 2024 EX-99.1

# # #

Columbia Banking System Announces $0.36 Per Common Share Dividend TACOMA, Wash., November 15, 2024 – Columbia Banking System, Inc. (“Columbia” Nasdaq: COLB), parent company of Umpqua Bank, today announced its Board of Directors has approved a quarterly cash dividend in the amount of $0.36 per common share, payable December 16, 2024, to shareholders of record as of November 29, 2024. About Columbia

November 5, 2024 EX-10.1

Columbia Banking System, Inc. Executive Change in Control and Severance Plan

Exhibit 10.1 COLUMBIA BANKING SYSTEM, INC. EXECUTIVE CHANGE IN CONTROL AND SEVERANCE PLAN 1. Establishment and Term of the Plan. (a) Establishment of the Plan. The purpose of this Columbia Banking System, Inc. Executive Change in Control and Severance Plan is to provide certain termination benefits to eligible executives of the Company and of the Bank. The Plan is an employee welfare benefit plan

November 5, 2024 EX-3.2

Amended and Restated Bylaws

AMENDED AND RESTATED BYLAWS OF COLUMBIA BANKING SYSTEM, INC. February 28, 2023 Exhibit 3.2 i TABLE OF CONTENTSTable of Contents Page ARTICLE 1 Meetings of Shareholders ......................................................................................................... 1 SECTION 1.1 – Shareholder Meetings. ........................................................................................

November 5, 2024 EX-10.2

Columbia Banking System, Inc. Form of Participation Agreement

Exhibit 10.2 PARTICIPATION AGREEMENT Dear [Executive], Re: Executive Participation Agreement Columbia Banking System, Inc. Executive Change in Control and Severance Plan Columbia Banking System, Inc. has established the Columbia Banking System, Inc. Executive Change in Control and Severance Plan. The Plan provides payments and benefits to certain eligible executives in the event of a Qualifying Te

November 5, 2024 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ Quarterly Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the quarterly period ended: September 30, 2024 or

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ Quarterly Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the quarterly period ended: September 30, 2024 or ☐ Transition Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the transition period from to . Commission File Number: 000-20288 COLUMBIA BANK

October 24, 2024 8-K

Regulation FD Disclosure, Financial Statements and Exhibits, Results of Operations and Financial Condition

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 and Exchange Act of 1934 Date of Report: October 24, 2024 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation

October 24, 2024 EX-99.2

3rd Quarter 2024 Earnings Presentation October 24, 2024 Disclaimer FORWARD-LOOKING STATEMENTS This presentation includes forward-looking statements within the meaning of the "Safe-Harbor" provisions of the Private Securities Litigation Reform Act of

3rd Quarter 2024 Earnings Presentation October 24, 2024 Disclaimer FORWARD-LOOKING STATEMENTS This presentation includes forward-looking statements within the meaning of the "Safe-Harbor" provisions of the Private Securities Litigation Reform Act of 1995, which management believes are a benefit to shareholders.

October 24, 2024 EX-99.1

COLUMBIA BANKING SYSTEM, INC. REPORTS THIRD QUARTER 2024 RESULTS

EXHIBIT 99.1 00 COLUMBIA BANKING SYSTEM, INC. REPORTS THIRD QUARTER 2024 RESULTS $146 million $143 million $0.70 $0.69 Net income Operating net income 1 Earnings per diluted common share Operating earnings per diluted common share 1 0 CEO Commentary “Our third quarter results reflect our continued work and success as we strive toward top-quartile performance,” said Clint Stein, President and CEO.

September 30, 2024 EX-99.1

# # #

Columbia Banking System Announces Date of Third Quarter 2024 Earnings Release and Conference Call TACOMA, Wash.

September 30, 2024 8-K

Regulation FD Disclosure, Financial Statements and Exhibits

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 and Exchange Act of 1934 Date of Report: September 30, 2024 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporati

August 12, 2024 EX-99.1

# # #

EX-99.1 2 colbex991dividendannouncem.htm EX-99.1 Columbia Banking System Announces $0.36 Per Common Share Dividend TACOMA, Wash., August 12, 2024 – Columbia Banking System, Inc. (“Columbia” Nasdaq: COLB), parent company of Umpqua Bank, today announced its Board of Directors has approved a quarterly cash dividend in the amount of $0.36 per common share, payable September 9, 2024, to shareholders of

August 12, 2024 8-K

Financial Statements and Exhibits, Other Events

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 and Exchange Act of 1934 Date of Report: August 12, 2024 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation

August 6, 2024 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ Quarterly Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the quarterly period ended: June 30, 2024 or

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ Quarterly Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the quarterly period ended: June 30, 2024 or ☐ Transition Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the transition period from to . Commission File Number: 000-20288 COLUMBIA BANKING S

July 25, 2024 8-K

Regulation FD Disclosure, Financial Statements and Exhibits, Results of Operations and Financial Condition

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 and Exchange Act of 1934 Date of Report: July 25, 2024 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation or

July 25, 2024 EX-99.2

2nd Quarter 2024 Earnings Presentation July 25, 2024 Disclaimer FORWARD-LOOKING STATEMENTS This presentation includes forward-looking statements within the meaning of the "Safe-Harbor" provisions of the Private Securities Litigation Reform Act of 199

2nd Quarter 2024 Earnings Presentation July 25, 2024 Disclaimer FORWARD-LOOKING STATEMENTS This presentation includes forward-looking statements within the meaning of the "Safe-Harbor" provisions of the Private Securities Litigation Reform Act of 1995, which management believes are a benefit to shareholders.

July 25, 2024 EX-99.1

COLUMBIA BANKING SYSTEM, INC. REPORTS SECOND QUARTER 2024 RESULTS

EXHIBIT 99.1 00 COLUMBIA BANKING SYSTEM, INC. REPORTS SECOND QUARTER 2024 RESULTS $120 million $140 million $0.57 $0.67 Net income Operating net income 1 Earnings per diluted common share Operating earnings per diluted common share 1 0 CEO Commentary "Our second quarter results reflect continued progress on our targeted actions to improve our financial performance and drive shareholder value,” sai

June 28, 2024 EX-99.1

# # #

Columbia Banking System Announces Date of Second Quarter 2024 Earnings Release and Conference Call TACOMA, Wash.

June 28, 2024 8-K

Regulation FD Disclosure, Financial Statements and Exhibits

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 and Exchange Act of 1934 Date of Report: June 28, 2024 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation or

June 25, 2024 11-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 11-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 11-K (Mark One) x ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended DECEMBER 31, 2023 OR [ ] TRANSITION REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to . Commission File Number.....000-20288 A. Full title of th

May 13, 2024 8-K

Financial Statements and Exhibits, Other Events

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 and Exchange Act of 1934 Date of Report: May 13, 2024 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation or

May 13, 2024 EX-99.1

# # #

Columbia Banking System Announces $0.36 Per Common Share Dividend TACOMA, Wash., May 13, 2024 – Columbia Banking System, Inc. (“Columbia” Nasdaq: COLB), parent company of Umpqua Bank, today announced its Board of Directors has approved a quarterly cash dividend in the amount of $0.36 per common share, payable June 10, 2024, to shareholders of record as of May 24, 2024. About Columbia Columbia (Nas

May 9, 2024 EX-10.3

10.3 Form of Restricted Stock Unit Agreement under 2024 Equity Incentive Plan

EXHIBIT 10.3 COLUMBIA BANKING SYSTEM, INC. RESTRICTED STOCK UNIT AGREEMENT THIS RESTRICTED STOCK UNIT AGREEMENT (“Agreement”) is entered into by and between Columbia Banking System, Inc. (“Company”) and [●] (“Grantee”). 1.Basic Terms of Award Number of Restricted Stock Units Subject to the Award: [●] Date of Award: [●] 2.Company hereby awards to Grantee the number of Restricted Stock Units (“RSUs”

May 9, 2024 EX-24.1

Power of Attorney (filed herewith)

Exhibit 24.1 POWER OF ATTORNEY KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Clint E. Stein and Ronald L. Farnsworth and each of them, his or her true and lawful attorneys-in-fact and agents, with full power to act separately and full power of substitution and resubstitution, for him or her and in his or her name, place and stead, in an

May 9, 2024 S-8

As filed with the Securities and Exchange Commission on May 8, 2024

As filed with the Securities and Exchange Commission on May 8, 2024 Registration No.

May 9, 2024 EX-10.1

Columbia Banking System, Inc. 2024 Equity Incentive Plan

EXHIBIT 10.1 COLUMBIA BANKING SYSTEM, INC. 2024 EQUITY INCENTIVE PLAN 1.Purpose of the Plan The purpose of the Plan is to attract and retain the services of employees and directors who are likely to make significant contributions to the success of Columbia Banking System, Inc. (the “Company”) and its Subsidiaries, to provide them with rewards for exceptional performance and contributions to the Co

May 9, 2024 EX-FILING FEES

Filing Fee Table (filed herewith)

Exhibit 107 Calculation of Filing Fee Tables Form S-8 (Form Type) Columbia Banking System, Inc.

May 9, 2024 EX-FILING FEES

Filing Fee Table (filed herewith)

Exhibit 107 Calculation of Filing Fee Tables Form S-8 (Form Type) Columbia Banking System, Inc.

May 9, 2024 EX-FILING FEES

Filing Fee Table (filed herewith)

Exhibit 107 Calculation of Filing Fee Tables Form S-8 (Form Type) Columbia Banking System, Inc.

May 9, 2024 EX-10.6

Second Amendment to Amended and Restated Employee Stock Purchase Plan of Columbia Banking System, Inc.

EXHIBIT 10.6 SECOND AMENDMENT TO AMENDED AND RESTATED EMPLOYEE STOCK PURCHASE PLAN OF COLUMBIA BANKING SYSTEM, INC. This Second Amendment (this "Amendment") to the Amended and Restated Employee Stock Purchase Plan of Columbia Banking System, Inc., is entered into by Columbia Banking System, Inc., a Washington corporation (the "Company"), as of January 24, 2024 (the "Effective Date"). Recitals A. T

May 9, 2024 EX-24.1

Power of Attorney (filed herewith)

Exhibit 24.1 POWER OF ATTORNEY KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Clint E. Stein and Ronald L. Farnsworth and each of them, his or her true and lawful attorneys-in-fact and agents, with full power to act separately and full power of substitution and resubstitution, for him or her and in his or her name, place and stead, in an

May 9, 2024 S-8

As filed with the Securities and Exchange Commission on May 08, 2024. Registration No. 333-_____ UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-8 REGISTRATION STATEMENT THE SECURITIES ACT OF 1933 COLUMBIA BANKING SYSTE

As filed with the Securities and Exchange Commission on May 08, 2024. Registration No. 333- UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-8 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 COLUMBIA BANKING SYSTEM, INC. (Exact Name of Registrant as Specified in Its Charter) Washington 91-1422237 (State or other jurisdiction of incorporation or organization) (

May 9, 2024 S-8

As filed with the Securities and Exchange Commission on May 08, 2024

As filed with the Securities and Exchange Commission on May 08, 2024 Registration No.

May 9, 2024 8-K

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Financial Statements and Exhibits, Submission of Matters to a Vote of Security Holders

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 and Exchange Act of 1934 Date of Report: May 8, 2024 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation or O

May 9, 2024 EX-10.2

10.2 Form of Restricted Stock Award Agreement under the 2024 Equity Incentive Plan

EXHIBIT 10.2 COLUMBIA BANKING SYSTEM, INC. RESTRICTED STOCK AGREEMENT THIS RESTRICTED STOCK AGREEMENT (“Agreement”) is entered into by and between Columbia Banking System, Inc. (“Company”) and [●] (“Grantee”). 1.Basic Terms of Award Number of Shares of Restricted Stock Subject to the Award: [●] Fair Market Value on Date of Award of Shares of Restricted Stock: [●] Amount Required to be Paid for Sha

May 9, 2024 EX-24.1

Power of Attorney (filed herewith)

Exhibit 24.1 POWER OF ATTORNEY KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Kumi Yamamoto Baruffi, his or her true and lawful attorney-in-fact and agent, with full power to act separately and full power of substitution and resubstitution, for him or her and in his or her name, place and stead, in any and all capacities, to sign the Reg

May 9, 2024 EX-10.4

Columbia Banking System, Inc. Form of Performance Stock Unit Agreement (ROTCE)

EXHIBIT 10.4 COLUMBIA BANKING SYSTEM, INC. PERFORMANCE STOCK UNIT AGREEMENT (ROTCE) THIS PERFORMANCE STOCK UNIT AGREEMENT (“Agreement”) is entered into by and between Columbia Banking System, Inc. (“Company”) and [●] (“Grantee”). 1.Basic Terms of Award Target Number of Performance Stock Units Subject to the Award: [●] Performance Period: [●] - [●] Date of Award: [●] 2.Company hereby awards to Gran

May 9, 2024 EX-10.5

Columbia Banking System, Inc. Form of Performance Stock Unit Agreement (TSR)

EXHIBIT 10.5 COLUMBIA BANKING SYSTEM, INC. PERFORMANCE STOCK UNIT AGREEMENT (TSR) THIS PERFORMANCE STOCK UNIT AGREEMENT (“Agreement”) is entered into by and between Columbia Banking System, Inc. (“Company”) and [●] (“Grantee”). 1.Basic Terms of Award Target Number of Performance Stock Units Subject to the Award: [●] Performance Period: [●] - [●] Date of Award: [●] 2.Company hereby awards to Grante

May 7, 2024 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ Quarterly Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the quarterly period ended: March 31, 2024 or

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ Quarterly Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the quarterly period ended: March 31, 2024 or ☐ Transition Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the transition period from to . Commission File Number: 000-20288 COLUMBIA BANKING

May 7, 2024 EX-10.2

Form of Umpqua Bank Endorsement Method Split Dollar Agreement

EXHIBIT 10.2 UMPQUA BANK ENDORSEMENT METHOD SPLIT DOLLAR AGREEMENT (By and Between UMPQUA BANK and [EXECUTIVE]1) Insurer/Policy: The Penn Mutual Life Insurance Company Policy # Protective Life Insurance Company Policy # Massachusetts Mutual Life Insurance Company Policy # The Lincoln National Life Insurance Company Policy # Bank: UMPQUA BANK Insured: [EXECUTIVE] Relationship of Insured to Bank: Ex

April 25, 2024 EX-99.1

COLUMBIA BANKING SYSTEM, INC. REPORTS FIRST QUARTER 2024 RESULTS

EXHIBIT 99.1 00 COLUMBIA BANKING SYSTEM, INC. REPORTS FIRST QUARTER 2024 RESULTS $0.59 $0.65 $23.68 $16.03 Earnings per diluted common share Operating earnings per diluted common share 1 Book value per common share Tangible book value per common share 1 0 CEO Commentary "Our first quarter results reflect early progress on our targeted actions to improve our financial performance and drive sharehol

April 25, 2024 8-K

Regulation FD Disclosure, Financial Statements and Exhibits, Results of Operations and Financial Condition

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 and Exchange Act of 1934 Date of Report: April 25, 2024 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation o

April 25, 2024 EX-99.2

1st Quarter 2024 Earnings Presentation April 25, 2024 Disclaimer FORWARD-LOOKING STATEMENTS This presentation includes forward-looking statements within the meaning of the "Safe-Harbor" provisions of the Private Securities Litigation Reform Act of 19

1st Quarter 2024 Earnings Presentation April 25, 2024 Disclaimer FORWARD-LOOKING STATEMENTS This presentation includes forward-looking statements within the meaning of the "Safe-Harbor" provisions of the Private Securities Litigation Reform Act of 1995, which management believes are a benefit to shareholders.

April 8, 2024 DEFA14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ☒ Filed by a Party other than the Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ☐ Definitive Proxy State

April 1, 2024 8-K

Regulation FD Disclosure, Financial Statements and Exhibits

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 and Exchange Act of 1934 Date of Report: April 1, 2024 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation or

April 1, 2024 EX-99.1

# # #

Columbia Banking System Announces Date of First Quarter 2024 Earnings Release and Conference Call TACOMA, Wash.

March 27, 2024 DEF 14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 14A SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 14A SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No.

March 27, 2024 DEFA14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 14A SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 14A SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No.

March 5, 2024 EX-99.1

March 2024 Investor Presentation Disclaimer FORWARD-LOOKING STATEMENTS This presentation includes forward-looking statements within the meaning of the "Safe-Harbor" provisions of the Private Securities Litigation Reform Act of 1995, which management

March 2024 Investor Presentation Disclaimer FORWARD-LOOKING STATEMENTS This presentation includes forward-looking statements within the meaning of the "Safe-Harbor" provisions of the Private Securities Litigation Reform Act of 1995, which management believes are a benefit to shareholders.

March 5, 2024 8-K

Regulation FD Disclosure, Financial Statements and Exhibits

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 and Exchange Act of 1934 Date of Report: March 4, 2024 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation or

March 4, 2024 8-K

Regulation FD Disclosure, Financial Statements and Exhibits

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 and Exchange Act of 1934 Date of Report: March 4, 2024 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation or

March 4, 2024 EX-99.1

March 2024 Investor Presentation Disclaimer FORWARD-LOOKING STATEMENTS This presentation includes forward-looking statements within the meaning of the "Safe-Harbor" provisions of the Private Securities Litigation Reform Act of 1995, which management

March 2024 Investor Presentation Disclaimer FORWARD-LOOKING STATEMENTS This presentation includes forward-looking statements within the meaning of the "Safe-Harbor" provisions of the Private Securities Litigation Reform Act of 1995, which management believes are a benefit to shareholders.

February 27, 2024 EX-21.1

Subsidiaries of the Company

Exhibit 21.1 Subsidiaries of Columbia Banking System, Inc. Name of Subsidiary State of Incorporation Other Names Under Which Business is Conducted Umpqua Bank Oregon Columbia Trust Company, Columbia Healthcare Banking, Columbia Private Bank, Columbia Wealth Advisors, Columbia Wealth Management, Umpqua Bank Home Lending, Umpqua Bank Equipment Leasing and Finance, Umpqua Bank Vendor Finance Financia

February 27, 2024 EX-97.1

rroneously Awarded Incentive-based Compensation, dated October 2, 2023

EXHIBIT 97.1 COLUMBIA BANKING SYSTEM, INC. POLICY FOR THE RECOVERY OF ERRONEOUSLY AWARDED INCENTIVE-BASED COMPENSATION I. BACKGROUND Columbia Banking System, Inc. (the “Company”) has adopted this policy (this “Policy”) to provide for the recovery or “clawback” of certain incentive compensation in the event of a Restatement. This Policy is intended to comply with, and will be interpreted to be cons

February 27, 2024 EX-19.1

Columbia Banking System, Inc. Insider Trading Policy and Procedures, dated March 1, 2023

Exhibit 19.1 Insider Trading Policy STATEMENT OF COMPANY POLICY OF COLUMBIA BANKING SYSTEM, INC. The Need for an Insider Trading Policy The federal securities laws prohibit certain purchases or sales of securities while aware of material nonpublic information or certain disclosures of material nonpublic information to others who then trade on such information. Insider trading violations are pursue

February 27, 2024 EX-10.71

Umpqua Bank Nonqualified Deferred Compensation Plan, Revised and Restated January 1, 2024

EXHIBIT 10.71 UMPQUA BANK NONQUALIFIED DEFERRED COMPENSATION PLAN Revised and Restated January 1, 2024 PREAMBLE Columbia Banking System, Inc. (the “Company”) is the current sponsor of the Umpqua Legacy Supplemental Retirement/Nonqualified Deferred Compensation Plan (the “Plan”). The Plan was most recently amended effective January 1, 2019 and was subsequently amended in 2022 to, among other things

February 27, 2024 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended: December 31, 2023 OR ☐ TRANSITION REPORT PURSUANT TO S

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended: December 31, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 for the transition period from to . Commission file number: 000-20288 COLUMBIA BANKING SYSTE

February 13, 2024 SC 13G/A

COLB / Columbia Banking System, Inc. / VANGUARD GROUP INC - SCHEDULE 13G/A Passive Investment

SC 13G/A 1 tv0647-columbiabankingsystem.htm SCHEDULE 13G/A SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Schedule 13G Under the Securities Exchange Act of 1934 (Amendment No.: 13)* Name of issuer: Columbia Banking System Inc Title of Class of Securities: Common Stock CUSIP Number: 197236102 Date of Event Which Requires Filing of this Statement: December 29, 2023 Check the appropriate b

February 9, 2024 8-K

Financial Statements and Exhibits, Other Events

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 and Exchange Act of 1934 Date of Report: February 9, 2024 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation

February 9, 2024 SC 13G/A

COLB / Columbia Banking System, Inc. / DIMENSIONAL FUND ADVISORS LP - SEC SCHEDULE 13G Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 1 )* Columbia Banking System Inc (Name of Issuer) Common Stock (Title of Class of Securities) 197236102 (CUSIP Number) December 29, 2023 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to designate the rule pursuant to which

February 9, 2024 EX-99.1

# # #

Columbia Banking System Announces $0.36 Per Common Share Dividend TACOMA, Wash., Feb. 9, 2024 – Columbia Banking System, Inc. ("Columbia" Nasdaq: COLB), parent company of Umpqua Bank, today announced its Board of Directors has approved a quarterly cash dividend in the amount of $0.36 per common share, payable March 11, 2024, to shareholders of record as of February 23, 2024. "The fundamental stren

January 30, 2024 SC 13G/A

COLB / Columbia Banking System, Inc. / FRANKLIN MUTUAL ADVISERS LLC Passive Investment

SC 13G/A 1 colu23a1.htm CUSIP NO. 197236102 13G Page 1 of 7 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 1)* COLUMBIA BANKING SYSTEM, INC. (Name of Issuer) Common Stock, No Par Value (Title of Class of Securities) 197236102 (CUSIP Number) December 31, 2023 (Date of Event Which Requires Filing of this S

January 24, 2024 8-K

Regulation FD Disclosure, Financial Statements and Exhibits, Results of Operations and Financial Condition

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 and Exchange Act of 1934 Date of Report: January 24, 2024 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation

January 24, 2024 EX-99.1

COLUMBIA BANKING SYSTEM, INC. REPORTS FOURTH QUARTER 2023 RESULTS

EXHIBIT 99.1 Fourth Quarter 2023 Results •Net income of $94 million, or $0.45 per diluted common share •Operating net income of $91 million, or $0.44 per diluted common share1 •Consolidated asset balances of $52 billion at quarter end •Loan balances of $37 billion and deposit balances of $42 billion at quarter end •Estimated CET1 and total capital ratios of 9.6% and 11.8% at quarter end 00 COLUMBI

January 24, 2024 EX-99.2

4th Quarter 2023 Earnings Presentation January 24, 2024 Disclaimer FORWARD-LOOKING STATEMENTS This presentation includes forward-looking statements within the meaning of the "Safe-Harbor" provisions of the Private Securities Litigation Reform Act of

4th Quarter 2023 Earnings Presentation January 24, 2024 Disclaimer FORWARD-LOOKING STATEMENTS This presentation includes forward-looking statements within the meaning of the "Safe-Harbor" provisions of the Private Securities Litigation Reform Act of 1995, which management believes are a benefit to shareholders.

December 29, 2023 EX-99.1

# # #

Columbia Banking System Announces Date of Fourth Quarter 2023 Earnings Release and Conference Call TACOMA, Wash.

December 29, 2023 8-K

Regulation FD Disclosure, Financial Statements and Exhibits

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 and Exchange Act of 1934 Date of Report: December 29, 2023 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporatio

November 13, 2023 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 and Exchange Act of 1934 Date of Report: November 13, 2023 (Date of earliest event reported) Columbia Ba

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 and Exchange Act of 1934 Date of Report: November 13, 2023 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporatio

November 13, 2023 EX-99.1

# # #

Columbia Banking System Announces $0.36 Per Common Share Dividend TACOMA, Wash., Nov 13, 2023 – Columbia Banking System, Inc. (“Columbia” Nasdaq: COLB), parent company of Umpqua Bank, today announced its Board of Directors has approved a quarterly cash dividend in the amount of $0.36 per common share, payable December 11, 2023, to shareholders of record as of November 24, 2023. About Columbia Colu

November 3, 2023 10-Q

United States Securities and Exchange Commission Washington, D.C. 20549 FORM 10-Q ☒ Quarterly Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the quarterly period ended: September 30, 2023 or

United States Securities and Exchange Commission Washington, D.C. 20549 FORM 10-Q ☒ Quarterly Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the quarterly period ended: September 30, 2023 or ☐ Transition Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the transition period from to . Commission File Number: 000-20288 COLUMBIA BANK

October 18, 2023 EX-99.2

3rd Quarter 2023 Earnings Presentation October 18, 2023 Disclaimer FORWARD-LOOKING STATEMENTS This presentation includes forward-looking statements within the meaning of the "Safe-Harbor" provisions of the Private Securities Litigation Reform Act of

3rd Quarter 2023 Earnings Presentation October 18, 2023 Disclaimer FORWARD-LOOKING STATEMENTS This presentation includes forward-looking statements within the meaning of the "Safe-Harbor" provisions of the Private Securities Litigation Reform Act of 1995, which management believes are a benefit to shareholders.

October 18, 2023 8-K

Regulation FD Disclosure, Financial Statements and Exhibits, Results of Operations and Financial Condition

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 and Exchange Act of 1934 Date of Report: October 18, 2023 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation

October 18, 2023 EX-99.1

COLUMBIA BANKING SYSTEM, INC. REPORTS THIRD QUARTER 2023 RESULTS

EXHIBIT 99.1 Third Quarter 2023 Results •Net income of $136 million, or $0.65 per diluted common share •Operating net income of $164 million, or $0.79 per diluted common share1 •Consolidated asset balances of $52 billion at quarter end •Loan balances of $37 billion and deposit balances of $42 billion at quarter end •Estimated CET1 and total capital ratios of 9.4% and 11.5% at quarter end 00 COLUMB

September 29, 2023 EX-99.1

# # #

Columbia Banking System Announces Date of Third Quarter 2023 Earnings Release and Conference Call TACOMA, Wash.

September 29, 2023 8-K

Regulation FD Disclosure, Financial Statements and Exhibits

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 and Exchange Act of 1934 Date of Report: September 29, 2023 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporati

August 14, 2023 8-K

Financial Statements and Exhibits, Other Events

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 and Exchange Act of 1934 Date of Report: August 14, 2023 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation

August 14, 2023 EX-99.1

# # #

Columbia Banking System Announces $0.36 Per Common Share Dividend TACOMA, Wash., August 14, 2023 – Columbia Banking System, Inc. (“Columbia” Nasdaq: COLB), parent company of Umpqua Bank, today announced its Board of Directors has approved a quarterly cash dividend in the amount of $0.36 per common share, payable September 11, 2023, to shareholders of record as of August 25, 2023. About Columbia Co

August 3, 2023 10-Q

United States Securities and Exchange Commission Washington, D.C. 20549 FORM 10-Q ☒ Quarterly Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the quarterly period ended: June 30, 2023 or

United States Securities and Exchange Commission Washington, D.C. 20549 FORM 10-Q ☒ Quarterly Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the quarterly period ended: June 30, 2023 or ☐ Transition Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the transition period from to . Commission File Number: 000-20288 COLUMBIA BANKING S

July 25, 2023 EX-4.4

Umpqua Bank 401(k) and Profit Sharing Plan Adoption Agreement, dated November 5, 2021 (filed herewith)

EX-4.4 Exhibit 4.4 PRE-APPROVED DEFINED CONTRIBUTION PLAN (PROFIT SHARING/401(K) PLAN) A FIDELITY PRE-APPROVED PLAN Adoption Agreement No. 001 For use With Fidelity Basic Plan Document No. 17 FMR LLC and its affiliates do not provide tax or legal advice. Nothing herein or in any attachments hereto should be construed, or relied upon, as tax or legal advice. IRS CIRCULAR 230 DISCLOSURE: To the exte

July 25, 2023 EX-4.8

Umpqua Bank 401(k) and Profit Sharing Plan Adoption Agreement, dated July 14, 2023 (filed herewith)

Exhibit 4.8 ADOPTION AGREEMENT ARTICLE 1 PROFIT SHARING/401(K) PLAN 1.01 PLAN INFORMATION (g) Plan Status: (4) ☒ Plan Merger Effective Dates. Certain plan(s) were merged into the Plan on or after the date specified in Subsection 1.01(g)(1) above. Please complete the appropriate subsection(s) of the Plan Mergers Addendum. 1.04 COVERAGE All Employees who meet the conditions specified below shall be

July 25, 2023 EX-FILING FEES

Filing Fee Table (filed herewith)

EX-FILING FEES Exhibit 107 Calculation of Filing Fee Tables Form S-8 (Form Type) Columbia Banking System, Inc.

July 25, 2023 EX-4.3

Umpqua Bank 401(k) and Profit Sharing Plan, dated June 30, 2020 (filed herewith)

Exhibit 4.3 PRE-APPROVED DEFINED CONTRIBUTION PLAN FIDELITY BASIC PLAN DOCUMENT NO. 17 FMR LLC and its affiliates do not provide tax or legal advice. Nothing herein or in any attachments hereto should be construed, or relied upon, as tax or legal advice. IRS CIRCULAR 230 DISCLOSURE: To the extent this document (including attachments), mentions or references any tax matter, it is not intended or wr

July 25, 2023 EX-24.1

Power of Attorney (filed herewith)

Exhibit 24.1 POWER OF ATTORNEY KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Clint E. Stein and Ronald L. Farnsworth and each of them, his or her true and lawful attorneys-in-fact and agents, with full power to act separately and full power of substitution and resubstitution, for him or her and in his or her name, place and stead, in an

July 25, 2023 EX-4.5

Umpqua Bank 401(k) and Profit Sharing Plan Adoption Agreement, dated December 23, 2022 (filed herewith)

Exhibit 4.5 PRE-APPROVED DEFINED CONTRIBUTION PLAN (PROFIT SHARING/401(K) PLAN) A FIDELITY PRE-APPROVED PLAN Adoption Agreement No. 001 For use With Fidelity Basic Plan Document No. 17 FMR LLC and its affiliates do not provide tax or legal advice. Nothing herein or in any attachments hereto should be construed, or relied upon, as tax or legal advice. IRS CIRCULAR 230 DISCLOSURE: To the extent this

July 25, 2023 EX-4.7

Umpqua Bank 401(k) and Profit Sharing Plan Adoption Agreement, dated February 28, 2023 (filed herewith)

Exhibit 4.7 PRE-APPROVED DEFINED CONTRIBUTION PLAN (PROFIT SHARING/401(K) PLAN) A FIDELITY PRE-APPROVED PLAN Adoption Agreement No. 001 For use With Fidelity Basic Plan Document No. 17 FMR LLC and its affiliates do not provide tax or legal advice. Nothing herein or in any attachments hereto should be construed, or relied upon, as tax or legal advice. IRS CIRCULAR 230 DISCLOSURE: To the extent this

July 25, 2023 S-8

As filed with the Securities and Exchange Commission on July 25, 2023

S-8 As filed with the Securities and Exchange Commission on July 25, 2023 Registration No.

July 25, 2023 EX-4.6

Umpqua Bank 401(k) and Profit Sharing Plan Adoption Agreement, dated December 28, 2022 (filed herewith)

EX-4.6 Exhibit 4.6 PRE-APPROVED DEFINED CONTRIBUTION PLAN (PROFIT SHARING/401(K) PLAN) A FIDELITY PRE-APPROVED PLAN Adoption Agreement No. 001 For use With Fidelity Basic Plan Document No. 17 FMR LLC and its affiliates do not provide tax or legal advice. Nothing herein or in any attachments hereto should be construed, or relied upon, as tax or legal advice. IRS CIRCULAR 230 DISCLOSURE: To the exte

July 19, 2023 EX-99.1

COLUMBIA BANKING SYSTEM, INC. REPORTS SECOND QUARTER 2023 RESULTS

EXHIBIT 99.1 Second Quarter 2023 Results •Net income of $133 million, or $0.64 per common share •Operating net income of $169 million, or $0.81 per common share1 •Consolidated asset balances of $54 billion at quarter end •Loan balances of $37 billion and deposit balances of $41 billion at quarter end •Estimated CET1 and total capital ratios of 9.1% and 11.1% at quarter end 00 COLUMBIA BANKING SYST

July 19, 2023 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 and Exchange Act of 1934 Date of Report: July 19, 2023 (Date of earliest event reported) Columbia Bankin

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 and Exchange Act of 1934 Date of Report: July 19, 2023 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation or

July 19, 2023 EX-99.2

2nd Quarter 2023 Earnings Presentation July 19, 2023 Disclaimer FORWARD-LOOKING STATEMENTS This presentation includes forward-looking statements within the meaning of the "Safe-Harbor" provisions of the Private Securities Litigation Reform Act of 199

colbq22023earningspresen 2nd Quarter 2023 Earnings Presentation July 19, 2023 Disclaimer FORWARD-LOOKING STATEMENTS This presentation includes forward-looking statements within the meaning of the "Safe-Harbor" provisions of the Private Securities Litigation Reform Act of 1995, which management believes are a benefit to shareholders.

June 30, 2023 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 and Exchange Act of 1934 Date of Report: June 30, 2023 (Date of earliest event reported) Columbia Bankin

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 and Exchange Act of 1934 Date of Report: June 30, 2023 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation or

June 30, 2023 EX-99.1

# # #

Columbia Banking System Announces Date of Second Quarter 2023 Earnings Release and Conference Call TACOMA, Wash.

June 28, 2023 11-K

Form 11-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 11-K (Mark One) x ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended DECEMBER 31, 2022 OR [ ] TRANSITION REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to . Commission File Number.....000-20288 A. Full title of th

June 27, 2023 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 and Exchange Act of 1934 Date of Report: June 27, 2023 (Date of earliest event reported) Columbia Bankin

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 and Exchange Act of 1934 Date of Report: June 27, 2023 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation or

May 23, 2023 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 and Exchange Act of 1934 Date of Report: May 18, 2023 (Date of earliest event reported) Columbia Banking

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 and Exchange Act of 1934 Date of Report: May 18, 2023 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation or

May 15, 2023 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 and Exchange Act of 1934 Date of Report: May 15, 2023 (Date of earliest event reported) Columbia Banking

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 and Exchange Act of 1934 Date of Report: May 15, 2023 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation or

May 15, 2023 EX-99.1

# # #

Columbia Banking System Announces Increase to Common Share Dividend TACOMA, Wash., May 15, 2023 – Columbia Banking System, Inc. (“Columbia” Nasdaq: COLB), parent company of Umpqua Bank, today announced its Board of Directors has approved a quarterly cash dividend in the amount of $0.36 per common share, representing a 20% increase to the most recent Columbia dividend declaration, which took place

May 9, 2023 EX-10.7

Letter Agreement, dated as of March 1, 2023, by and between Columbia Banking System, Inc. and Sheri Burns

Exhibit 10.7 March 1, 2023 Sheri Burns 5885 Meadows Road Lake Oswego, Oregon 97035 Dear Sheri: As you know, the merger (the “Merger”) contemplated by the Agreement and Plan of Merger, dated as of October 11, 2021, by and between Umpqua Holdings Corporation (“Umpqua”), Columbia Banking System, Inc. (“Columbia”) and Cascade Merger Sub, Inc. has been successfully completed. We greatly appreciate your

May 9, 2023 EX-10.14

Second Amendment to the Columbia State Bank Supplemental Executive Retirement Plan Agreement, dated as of February 28, 2023, by and between Columbia State Bank and Kumi Baruffi

Exhibit 10.14 SECOND AMENDMENT TO THE COLUMBIA STATE BANK SUPPLEMENTAL EXECUTIVE RETIREMENT PLAN AGREEMENT (By and Between Columbia State Bank and Kumi Baruffi) This Second Amendment to the Columbia State Bank Supplemental Executive Retirement Plan Agreement (hereinafter "Amendment"), is hereby entered into this February 28th, 2023 by and between Columbia State Bank (hereinafter "Bank" or "Employe

May 9, 2023 EX-10.10

Letter Agreement, dated as of March 1, 2023, by and between Columbia Banking System, Inc. and Andrew Ognall

Exhibit 10.10 March 1, 2023 Andrew Ognall 5885 Meadows Road Lake Oswego, Oregon 97035 Dear Andrew: As you know, the merger (the “Merger”) contemplated by the Agreement and Plan of Merger, dated as of October 11, 2021, by and between Umpqua Holdings Corporation (“Umpqua”), Columbia Banking System, Inc. (“Columbia”) and Cascade Merger Sub, Inc., has been successfully completed. We greatly appreciate

May 9, 2023 EX-10.11

Letter Agreement, dated as of March 1, 2023, by and between Columbia Banking System, Inc. and Kumi Baruffi

Exhibit 10.11 March 1, 2023 Kumi Baruffi 1301 A Street, Suite 800 Tacoma, Washington 98401-2156 Dear Kumi: As you know, the merger (the “Merger”) contemplated by the Agreement and Plan of Merger, dated as of October 11, 2021, by and between Umpqua Holdings Corporation (“Umpqua”), Columbia Banking System, Inc. (“Columbia”) and Cascade Merger Sub, Inc. has been successfully completed. We greatly app

May 9, 2023 EX-10.16

First Amendment to Columbia Banking System, Inc. 2023 Deferred Compensation Plan, dated as of April 18, 2023

Exhibit 10.16 FIRST AMENDMENT TO COLUMBIA BANKING SYSTEM, INC. 2023 DEFERRED COMPENSATION PLAN THIS AMENDMENT, dated effective as of March 1, 2023 (the “Effective Date”), is here by adopted by Columbia Banking System, Inc. (the “Company”) on April 18, 2023. Recitals A.The Company entered into a deferred compensation arrangement with a select group of highly compensated employees of Columbia Bankin

May 9, 2023 EX-10.13

Letter Agreement, dated as of March 1, 2023, by and between Columbia Banking System, Inc. and David Moore Devine

Exhibit 10.13 March 1, 2023 David Moore-Devine 1301 A Street, Suite 800 Tacoma, Washington 98401-2156 Dear David: As you know, the merger (the “Merger”) contemplated by the Agreement and Plan of Merger, dated as of October 11, 2021, by and between Umpqua Holdings Corporation (“Umpqua”), Columbia Banking System, Inc. (“Columbia”) and Cascade Merger Sub, Inc. has been successfully completed. We grea

May 9, 2023 EX-10.12

Letter Agreement, dated as of March 1, 2023, by and between Columbia Banking System, Inc. and Lisa Dow

Exhibit 10.12 March 1, 2023 Lisa Dow 1301 A Street, Suite 800 Tacoma, Washington 98401-2156 Dear Lisa: As you know, the merger (the “Merger”) contemplated by the Agreement and Plan of Merger, dated as of October 11, 2021, by and between Umpqua Holdings Corporation (“Umpqua”), Columbia Banking System, Inc. (“Columbia”) and Cascade Merger Sub, Inc. has been successfully completed. We greatly appreci

May 9, 2023 EX-3.1

Restated Articles of Incorporation

Exhibit 3.1 RESTATED ARTICLES OF INCORPORATION OF COLUMBIA BANKING SYSTEM, INC. ARTICLE 1 Section 1.1 The name of the corporation shall be COLUMBIA BANKING SYSTEM, INC. ARTICLE 2 Section 2.1 The corporation’s period of duration shall be perpetual. ARTICLE 3 Section 3.1 The purpose for which the corporation is organized is the transaction of any and all lawful business for which corporations may be

May 9, 2023 10-Q

United States Securities and Exchange Commission Washington, D.C. 20549 FORM 10-Q ☒ Quarterly Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the quarterly period ended: March 31, 2023 or

United States Securities and Exchange Commission Washington, D.C. 20549 FORM 10-Q ☒ Quarterly Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the quarterly period ended: March 31, 2023 or ☐ Transition Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the transition period from to . Commission File Number: 000-20288 COLUMBIA BANKING

May 9, 2023 EX-10.8

Letter Agreement, dated as of March 1, 2023, by and between Columbia Banking System, Inc. and Frank Namdar

Exhibit 10.8 March 1, 2023 Frank Namdar 5885 Meadows Road Lake Oswego, Oregon 97035 Dear Frank: As you know, the merger (the “Merger”) contemplated by the Agreement and Plan of Merger, dated as of October 11, 2021, by and between Umpqua Holdings Corporation (“Umpqua”), Columbia Banking System, Inc. (“Columbia”) and Cascade Merger Sub, Inc. has been successfully completed. We greatly appreciate you

May 9, 2023 EX-10.6

Letter Agreement, dated as of March 1, 2023, by and between Columbia Banking System, Inc. and Drew Anderson

Exhibit 10.6 March 1, 2023 Drew Anderson 5885 Meadows Road Lake Oswego, Oregon 97035 Dear Drew: As you know, the merger (the “Merger”) contemplated by the Agreement and Plan of Merger, dated as of October 11, 2021, by and between Umpqua Holdings Corporation (“Umpqua”), Columbia Banking System, Inc. (“Columbia”) and Cascade Merger Sub, Inc. has been successfully completed. We greatly appreciate you

May 9, 2023 EX-10.9

Letter Agreement, dated as of March 1, 2023, by and between Columbia Banking System, Inc. and Tory Nixon

Exhibit 10.9 March 1, 2023 Torran Nixon 1301 A Street, Suite 800 Tacoma, Washington 98401-2156 Dear Tory: As you know, the merger (the “Merger”) contemplated by the Agreement and Plan of Merger, dated as of October 11, 2021, by and between Umpqua Holdings Corporation (“Umpqua”), Columbia Banking System, Inc. (“Columbia”) and Cascade Merger Sub, Inc., has been successfully completed. We greatly app

April 26, 2023 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 and Exchange Act of 1934 Date of Report: April 26, 2023 (Date of earliest event reported) Columbia Banki

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 and Exchange Act of 1934 Date of Report: April 26, 2023 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation o

April 26, 2023 EX-99.2

1st Quarter 2023 Earnings Presentation April 26, 2023 Disclaimer FORWARD-LOOKING STATEMENTS This presentation includes forward-looking statements within the meaning of the "Safe-Harbor" provisions of the Private Securities Litigation Reform Act of 19

colbq12023earningspresen 1st Quarter 2023 Earnings Presentation April 26, 2023 Disclaimer FORWARD-LOOKING STATEMENTS This presentation includes forward-looking statements within the meaning of the "Safe-Harbor" provisions of the Private Securities Litigation Reform Act of 1995, which management believes are a benefit to shareholders.

April 26, 2023 EX-99.1

COLUMBIA BANKING SYSTEM, INC. REPORTS FIRST QUARTER 2023 RESULTS

EXHIBIT 99.1 First Quarter 2023 Results •Net income of $(14) million, or $(0.09) per common share •Operating net income of $72 million, or $0.46 per common share1 •Successfully closed merger with Umpqua Holdings Corporation and completed core systems conversion •Consolidated asset balances increased $22 billion to $54 billion at quarter end •Loan balances of $37 billion and deposit balances of $42

April 6, 2023 DEFA14A

SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No.

April 6, 2023 DEF 14A

Definitive Proxy Statement

TABLE OF CONTENTS SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No.

April 3, 2023 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 and Exchange Act of 1934 Date of Report: March 31, 2023 (Date of earliest event reported) Columbia Banki

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 and Exchange Act of 1934 Date of Report: March 31, 2023 (Date of earliest event reported) Columbia Banking System, Inc. (Exact Name of Registrant as Specified in Its Charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation o

April 3, 2023 EX-99.1

Columbia Banking System Announces Date of First Quarter 2023 Earnings Release and Conference Call

Columbia Banking System Announces Date of First Quarter 2023 Earnings Release and Conference Call TACOMA, Wash.

March 3, 2023 EX-99.2

UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION

EX-99.2 Exhibit 99.2 UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION The following unaudited pro forma condensed combined financial information combines the historical consolidated financial position and results of operations of Columbia Banking System, Inc. (“Columbia”) and Umpqua Holdings Corporation (“Umpqua”) as a reverse acquisition of Columbia by Umpqua. The merger of Columbia a

March 3, 2023 8-K/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K/A CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): February 28, 2023 Columbia Bank

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K/A CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): February 28, 2023 Columbia Banking System, Inc. (Exact name of registrant as specified in its charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation

March 1, 2023 EX-10.7

Columbia Banking System, Inc. 2023 Deferred Compensation Plan

Exhibit 10.7 COLUMBIA BANKING SYSTEM, INC. 2023 DEFERRED COMPENSATION PLAN I. Establishment and Purpose of Plan Columbia Banking System, Inc. hereby establishes the Columbia Banking System, Inc. 2023 Deferred Compensation Plan (the “Plan”), effective as of March 1, 2023. The Plan is intended to provide deferred compensation for a select group of highly compensated employees of Columbia Banking Sys

March 1, 2023 EX-10.5

Letter Agreement, dated as of March 1, 2023, by and between Columbia Banking System, Inc. and Eric Eid

EX-10.5 8 d413616dex105.htm EX-10.5 Exhibit 10.5 March 1, 2023 Eric Eid 1301 A Street, Suite 800 Tacoma, Washington 98401-2156 Dear Eric: As you know, the merger (the “Merger”) contemplated by the Agreement and Plan of Merger, dated as of October 11, 2021, by and between Umpqua Holdings Corporation (“Umpqua”), Columbia Banking System, Inc. (“Columbia”) and Cascade Merger Sub, Inc. has been success

March 1, 2023 EX-99.1

Columbia Banking System and Umpqua Holdings Corporation Complete Merger Two Leading Community Banks Based in the Northwest Combine to Create One of the Largest Banks Headquartered in the West

EX-99.1 Exhibit 99.1 Columbia Banking System and Umpqua Holdings Corporation Complete Merger Two Leading Community Banks Based in the Northwest Combine to Create One of the Largest Banks Headquartered in the West TACOMA, WASHINGTON | PORTLAND, OREGON, March 1, 2023 – Columbia Banking System, Inc. (“Columbia”) (Nasdaq: COLB), the parent company of Columbia Bank, and Umpqua Holdings Corporation (“Um

March 1, 2023 EX-4.6

Sterling Financial Corporation 2010 Long-Term Incentive Plan

EX-4.6 Exhibit 4.6 STERLING FINANCIAL CORPORATION 2010 LONG-TERM INCENTIVE PLAN Date of Board Approval: September 8, 2010 Date of Shareholder Approval: December 7, 2010 1. PURPOSES OF THE PLAN. The purpose of the Sterling Financial Corporation 2010 Long-Term Incentive Plan (the “Plan”) is to: a) foster and promote the long-term financial success of Sterling Financial Corporation (“Sterling”) and m

March 1, 2023 EX-10.4

Letter Agreement, dated as of March 1, 2023, by and between Columbia Banking System, Inc. and Aaron Deer

EX-10.4 Exhibit 10.4 March 1, 2023 Aaron Deer 1301 A Street, Suite 800 Tacoma, Washington 98401-2156 Dear Aaron: As you know, the merger (the “Merger”) contemplated by the Agreement and Plan of Merger, dated as of October 11, 2021, by and between Umpqua Holdings Corporation (“Umpqua”), Columbia Banking System, Inc. (“Columbia”) and Cascade Merger Sub, Inc. has been successfully completed. We great

March 1, 2023 EX-10.2

Letter Agreement, dated as of March 1, 2023, by and between Columbia Banking System, Inc. and Ronald Farnsworth

EX-10.2 Exhibit 10.2 March 1, 2023 Ronald Farnsworth 5885 Meadows Road Lake Oswego, Oregon 97035 Dear Ron: As you know, the merger (the “Merger”) contemplated by the Agreement and Plan of Merger, dated as of October 11, 2021, by and between Umpqua Holdings Corporation (“Umpqua”), Columbia Banking System, Inc. (“Columbia”) and Cascade Merger Sub, Inc. has been successfully completed. We greatly app

March 1, 2023 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): February 28, 2023 Columbia Bankin

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): February 28, 2023 Columbia Banking System, Inc. (Exact name of registrant as specified in its charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation or

March 1, 2023 EX-24.1

Power of Attorney (filed herewith)

EX-24.1 Exhibit 24.1 POWER OF ATTORNEY KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Clint E. Stein and Ronald L. Farnsworth and each of them, his or her true and lawful attorneys-in-fact and agents, with full power to act separately and full power of substitution and resubstitution, for him or her and in his or her name, place and stea

March 1, 2023 EX-3.4

Amended and Restated Bylaws

EX-3.4 Exhibit 3.4 AMENDED AND RESTATED BYLAWS OF COLUMBIA BANKING SYSTEM, INC. February 28, 2023 TABLE OF CONTENTS Page ARTICLE 1 Meetings of Shareholders 1 SECTION 1.1 - Shareholder Meetings 1 SECTION 1.2 - Annual Meeting 1 SECTION 1.3 - Special Meetings 1 SECTION 1.4 - Nominations and Business at Annual and Special Meetings 1 SECTION 1.5 - Notice 1 SECTION 1.6 - Quorum; Vote Required 1 SECTION

March 1, 2023 S-8

As filed with the Securities and Exchange Commission on March 1, 2023

S-8 As filed with the Securities and Exchange Commission on March 1, 2023 Registration No.

March 1, 2023 EX-3.3

Articles of Amendment of Columbia Banking System, Inc., dated February 28, 2023 (incorporated by reference to Exhibit 3.3 to the Form 8-K filed March 1, 2023)

EX-3.3 Exhibit 3.3 ARTICLES OF AMENDMENT OF COLUMBIA BANKING SYSTEM, INC. THESE ARTICLES OF AMENDMENT of the Amended and Restated Articles of Incorporation of Columbia Banking System, Inc., a Washington corporation, are executed and delivered for filing in accordance with the provisions of Section 23B.10.060 of the Washington Business Corporation Act: 1. The name of the corporation is: Columbia Ba

March 1, 2023 EX-10.6

Letter Agreement, dated as of March 1, 2023, by and between Columbia Banking System, Inc. and Christopher Merrywell

EX-10.6 Exhibit 10.6 March 1, 2023 Christopher Merrywell 1301 A Street, Suite 800 Tacoma, Washington 98401-2156 Dear Chris: As you know, the merger (the “Merger”) contemplated by the Agreement and Plan of Merger, dated as of October 11, 2021, by and between Umpqua Holdings Corporation (“Umpqua”), Columbia Banking System, Inc. (“Columbia”) and Cascade Merger Sub, Inc. has been successfully complete

March 1, 2023 EX-4.5

Umpqua Holdings Corporation 2013 Incentive Plan

EX-4.5 Exhibit 4.5 UMPQUA HOLDINGS CORPORATION 2013 INCENTIVE PLAN 1. PURPOSE. The purpose of this Plan is to enable the Company, and any Affiliate, to motivate, attract and retain the types of Employees, Consultants and Directors who will contribute to the Company’s success by providing incentives that offer an opportunity to participate in the Company’s future performance and align the interests

March 1, 2023 EX-10.1

Letter Agreement, dated as of October 11, 2021, by and between Columbia Banking System, Inc. and Cort O’Haver.

EX-10.1 Exhibit 10.1 October 11, 2021 Mr. Cort O’Haver At the address on file with the Company Dear Cort: This letter (this “Letter Agreement”) memorializes our agreement regarding the terms of your employment with, and service to, Columbia Banking System, Inc. (the “Company”) following the completion of the Merger contemplated by the Agreement and Plan of Merger, by and among Umpqua Holdings Corp

March 1, 2023 EX-FILING FEES

Filing Fee Table (filed herewith)

EX-FILING FEES Exhibit 107 Calculation of Filing Fee Tables Form S-8 (Form Type) Columbia Banking System, Inc.

March 1, 2023 EX-10.3

Letter Agreement, dated as of March 1, 2023, by and between Columbia Banking System, Inc. and Lisa White

EX-10.3 Exhibit 10.3 March 1, 2023 Lisa White 5885 Meadows Road Lake Oswego, Oregon 97035 Dear Lisa: As you know, the merger (the “Merger”) contemplated by the Agreement and Plan of Merger, dated as of October 11, 2021, by and between Umpqua Holdings Corporation (“Umpqua”), Columbia Banking System, Inc. (“Columbia”) and Cascade Merger Sub, Inc. has been successfully completed. We greatly appreciat

February 27, 2023 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): February 24, 2023 Columbia Bankin

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): February 24, 2023 Columbia Banking System, Inc. (Exact name of registrant as specified in its charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation or

February 24, 2023 EX-10.33

First Amendment to the Employment Agreement and the A&R Employment Agreement, dated as of December 31, 2022, by and between Columbia Banking System, Inc. and Clint E. Stein

EXHIBIT 10.33 AMENDMENT NO. 1 TO THE EMPLOYMENT AGREEMENT AND THE A&R EMPLOYMENT AGREEMENT This AMENDMENT NO. 1 (this “Amendment”), effective as of December 31, 2022, to the Employment Agreement dated as of September 30, 2019 (the “Employment Agreement”), by and among Columbia State Bank, a Washington banking corporation (“Columbia Bank”), together with Columbia Banking System, Inc., a Washington

February 24, 2023 EX-10.20

Amendment to Columbia Banking System, Inc. 2016 401 Plus Plan (deferred Compensation Plan), dated November 14, 2022

EXHIBIT 10.20 AMENDMENT TO COLUMBIA BANKING SYSTEM, INC. 2016 401 PLUS PLAN THIS AMENDMENT, effective as of January 1, 2023 (the "Effective Date"), is hereby adopted by Columbia Banking System, Inc. (the "Company") on November 14, 2022. Recitals A.The Company established the 2016 401 Plus Plan (the "Plan") to provide deferred compensation for the directors and a select group of senior management a

February 24, 2023 10-K

Form 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2022 ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Commission File Number 000-20288 COLUMBIA BANKING SYSTEM, INC. (Exact name of registrant as spec

February 24, 2023 EX-10.1

2018 Equity Incentive Plan (as amended through May 22, 2019)

EXHIBIT 10.1 2018 EQUITY INCENTIVE PLAN OF COLUMBIA BANKING SYSTEM, INC. (as amended through May 22, 2019) 1.Purpose of the Plan The purpose of the Plan is to attract and retain the most talented employees and directors available to serve in positions of responsibility with Columbia Banking System, Inc. and its subsidiaries, to provide them with both rewards for exceptional performance and long-te

February 24, 2023 EX-10.2

Form of Restricted Stock Agreement

EXHIBIT 10.2 COLUMBIA BANKING SYSTEM, INC. RESTRICTED STOCK AGREEMENT THIS RESTRICTED STOCK AGREEMENT (“Agreement”) is entered into by and between Columbia Banking System, Inc. (“Company”) and (“Grantee”). 1.Basic Terms of Award Number of Shares of Restricted Stock Subject to the Award: Fair Market Value on Date of Award of Shares of Restricted Stock: $ Amount Required to be Paid for Shares of Res

February 24, 2023 EX-10.4

Form of Performance Stock Unit Agreement

EXHIBIT 10.4 COLUMBIA BANKING SYSTEM, INC. PERFORMANCE STOCK UNIT AGREEMENT THIS PERFORMANCE STOCK UNIT AGREEMENT (“Agreement”) is entered into by and between Columbia Banking System, Inc. (“Company”) and (“Grantee”). 1.Basic Terms of Award Target Number of Performance Stock Units Subject to the Award: Performance Period: Date of Award: 2.Company hereby awards to Grantee the target number of Perfo

February 24, 2023 EX-24

Power of Attorney

EXHIBIT 24 POWER OF ATTORNEY The director of Columbia Banking System, Inc. (the “Company”), whose signature appears below, hereby appoints Clint E. Stein and Craig D. Eerkes, or either of them, as his/her attorney to sign, in his/her name and behalf and in any and all capacities stated below, the Company's Form 10-K Annual Report pursuant to Section 13 of the Securities Exchange Act of 1934, and l

February 24, 2023 EX-10.18

Amendment to Amended and Restated Columbia Banking System, Inc. 2005 401 Plus Plan (Deferred Compensation plan), dated November 14, 2022

EXHIBIT 10.18 AMENDMENT TO AMENDED AND RESTATED COLUMBIA BANKING SYSTEM, INC. 2005 401 PLUS PLAN THIS AMENDMENT, effective as of January 1, 2023 (the "Effective Date"), is hereby adopted by Columbia Banking System, Inc. (the "Company") on November 14, 2022. Recitals A.The Company entered into a deferred compensation arrangement with certain of its directors and a select group of senior management

February 24, 2023 EX-10.32

Amended and Restated Employment Agreement, dated as of October 11, 2021, by and between Columbia Banking System, Inc. and Clint E. Stein

EXHIBIT 10.32 EXECUTION VERSION CONFIDENTIAL AMENDED & RESTATED EMPLOYMENT AGREEMENT This AMENDED & RESTATED EMPLOYMENT AGREEMENT (this “Agreement”), dated as of October 11, 2021, by and between Columbia State Bank, a Washington banking corporation (“Columbia Bank”), together with Columbia Banking System, Inc., a Washington corporation (“CBSI”) and, as applicable, its subsidiaries and affiliates (

February 24, 2023 EX-10.3

Form of Restricted Stock Unit Agreement

EXHIBIT 10.3 COLUMBIA BANKING SYSTEM, INC. RESTRICTED STOCK UNIT AGREEMENT THIS RESTRICTED STOCK UNIT AGREEMENT (“Agreement”) is entered into by and between Columbia Banking System, Inc. (“Company”) and (“Grantee”). 1.Basic Terms of Award Number of Restricted Stock Units Subject to the Award: Date of Award: 2.Company hereby awards to Grantee the number of Restricted Stock Units (“RSUs”) described

February 24, 2023 EX-21

Subsidiaries of the Company

EXHIBIT 21 SUBSIDIARIES OF THE COMPANY Name of Subsidiary State of Incorporation Ownership Columbia State Bank Washington 100 % Columbia Trust Company Oregon 100 %

February 10, 2023 SC 13G

COLB / Columbia Banking System Inc / DIMENSIONAL FUND ADVISORS LP - SEC SCHEDULE 13G Passive Investment

SC 13G 1 SEC13GFiling.htm SEC SCHEDULE 13G UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. )* Columbia Banking System Inc (Name of Issuer) Common Stock (Title of Class of Securities) 197236102 (CUSIP Number) December 30, 2022 (Date of Event Which Requires Filing of this Statement) Check the appropriate bo

February 9, 2023 SC 13G/A

COLB / Columbia Banking System Inc / VANGUARD GROUP INC - SCHEDULE 13G/A Passive Investment

SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Schedule 13G Under the Securities Exchange Act of 1934 (Amendment No.: 12)* Name of issuer: Columbia Banking System Inc. Title of Class of Securities: Common Stock CUSIP Number: 197236102 Date of Event Which Requires Filing of this Statement: December 30, 2022 Check the appropriate box to designate the rule pursuant to which this Schedule i

January 30, 2023 SC 13G

COLB / Columbia Banking System Inc / FRANKLIN MUTUAL ADVISERS LLC Passive Investment

colu22in.htm - Generated by SEC Publisher for SEC Filing CUSIP NO. 197236102 13G Page 1 of 7 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. )* COLUMBIA BANKING SYSTEM, INC. (Name of Issuer) Common Stock, No Par Value (Title of Class of Securities) 197236102 (CUSIP Number) December 31, 2022 (Date of Event

January 24, 2023 EX-99.1

Columbia Banking System Announces Fourth Quarter and Full Year 2022 Results and Quarterly Cash Dividend

Exhibit 99.1 FOR IMMEDIATE RELEASE January 24, 2023 Columbia Banking System Announces Fourth Quarter and Full Year 2022 Results and Quarterly Cash Dividend Notable Items for Fourth Quarter and Fiscal Year 2022 •Record full year net income of $250.2 million and diluted earnings per share of $3.20 •Record quarterly net income of $68.9 million and diluted earnings per share of $0.88, which included a

January 24, 2023 8-K

Financial Statements and Exhibits, Results of Operations and Financial Condition, Other Events

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): January 24, 2023 COLUMBIA BANKING SYSTEM, INC. (Exact name of registrant as specified in its charter) Washington 000-20288 91-1422237 (State or other jurisdiction of incorporation) (C

January 10, 2023 EX-2.1

Amendment No. 1, dated as of January 9, 2023, to the Agreement and Plan of Merger, dated as of October 11, 2021, by and among Umpqua Holdings Corporation, Columbia Banking System, Inc. and Cascade Merger Sub, Inc. (incorporated by reference to Exhibit 2.1 of Columbia Banking System, Inc.’s Form 8-K filed with the SEC on January 10, 2023 (File No. 000-20288)).

Exhibit 2.1 AMENDMENT NO. 1 TO THE MERGER AGREEMENT This AMENDMENT NO. 1 (this “Amendment”), dated as of January 9, 2023, to the Agreement and Plan of Merger, dated as of October 11, 2021 (together with the exhibits and schedules thereto, the “Merger Agreement”), by and among Columbia Banking System, Inc., a Washington corporation (“Columbia”), Umpqua Holdings Corporation, an Oregon corporation (“

January 10, 2023 EX-99.1

Columbia Banking System and Umpqua Holdings Corporation Announce FDIC Approval and Expected Closing Timeline for Combination

EX-99.1 Exhibit 99.1 Columbia Banking System and Umpqua Holdings Corporation Announce FDIC Approval and Expected Closing Timeline for Combination TACOMA, WASHINGTON | PORTLAND, OREGON, January 9, 2023 – Columbia Banking System, Inc. (“Columbia”) (NASDAQ: COLB), the parent company of Columbia Bank, and Umpqua Holdings Corporation (“Umpqua”) (NASDAQ: UMPQ), the parent company of Umpqua Bank, jointly

January 10, 2023 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): January 9, 2023 Columbia Banking

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): January 9, 2023 Columbia Banking System, Inc. (Exact name of registrant as specified in its charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation or O

January 6, 2023 8-K

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers

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): December 31, 2022 Columbia Banking System, Inc. (Exact name of registrant as specified in its charter) Washington 000-20288 91-1422237 (State or Other Jurisdiction of Incorporation or

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