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: 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 or Organization)	(Commission File Number)	(I.R.S. Employer Identification Number)

1301 A Street

Tacoma, Washington 98402-2156

(address of Principal Executive Offices)(Zip Code)

(253) 305-1900

(Registrant's Telephone Number, Including Area Code)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

[ ☐ ]    Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

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

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

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

Securities registered pursuant to Section 12(b) of the Act:

TITLE OF EACH CLASS	TRADING SYMBOL	NAME OF EXCHANGE
Common Stock, No Par Value	COLB	The NASDAQ Stock Market LLC

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company [ ☐ ]

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. [ ]

Item 2.02 Results of Operations and Financial Condition.

On October 18, 2023, Columbia Banking System, Inc. issued a press release announcing third quarter 2023 financial results. The release is attached hereto as Exhibit 99.1. The information included in the press release is considered to be "furnished" under the Securities Exchange Act of 1934, as amended (the "Exchange Act"). Columbia Banking System, Inc. will include final financial statements and additional analyses for the quarter ended September 30, 2023 as part of its quarterly report on Form 10-Q covering that period.

 

Item 7.01 Regulation FD Disclosure.

Columbia Banking System, Inc. is filing an investor slide presentation that it intends to review in conjunction with its earnings release conference call on October 18, 2023. The slides are included as Exhibit 99.2 to this report and shall not be deemed to be "filed" for the purposes of Section 18 of the Exchange Act, or otherwise subject to the liability of that section, and shall not be incorporated by reference into any registration statement or other document filed under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such filing.

Item 9.01	Financial Statements and Exhibits.
(d)	EXHIBITS
	99.1 Press Release announcing third quarter 2023 financial results dated October 18, 2023
	99.2 Third Quarter 2023 Investor Presentation
	104 Cover Page Interactive Data File (embedded within the Inline XBRL document)

SIGNATURES

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

 

	Columbia Banking System, Inc. (Registrant)
Dated: October 18, 2023	By: /s/ Ronald L. Farnsworth        Ronald L. Farnsworth       Executive Vice President/Chief Financial Officer

EX-99.1

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

COLUMBIA BANKING SYSTEM, INC. REPORTS THIRD QUARTER 2023 RESULTS
$0.65	$0.79	$22.21	$14.22
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 teams remain focused on their customers and communities as we continue to drive balanced growth for the organization,” said Clint Stein, President and CEO. “We are back to business as usual, and our third quarter results highlight stabilizing customer deposit trends, relationship-driven growth in our loan portfolio and customer-based fee income, and a smaller impact from merger-related expense that affect our reported results. We achieved $140 million in annualized net merger-related cost savings through quarter end, surpassing our originally announced target of $135 million despite continued investment in our growing franchise, which includes the opening of our first branch in Utah during the third quarter. Our talented associates, expanding footprint, and customer-focused business model enable us to continue to win business and drive shareholder value.”

–Clint Stein, President and CEO of Columbia Banking System, Inc.

3Q23 HIGHLIGHTS (COMPARED TO 2Q23)
Net Interest Income and NIM	•Net interest income decreased by $3 million or 1% on a linked-quarter basis as the increase in interest income due to higher yields was more than offset by higher funding costs.
	•Net interest margin was 3.91%, down 2 basis points from the prior quarter. The second full quarter as a combined organization, higher customer balances, and consistent purchase accounting trends contributed to net interest margin stabilization between quarters.
Non-Interest Income and Expense	•Non-interest income increased by $4 million due primarily to higher customer-related fee income and loan gain-on-sale income as well as a lower loss due to cumulative non-merger fair value accounting and hedges.
	•Non-interest expense decreased by $24 million due to the realization of cost savings and lower merger-related expense.
Credit Quality	•Net charge-offs were 0.25% of average loans and leases (annualized) compared to 0.30% in the prior quarter. Charge-off activity remains centered in the FinPac portfolio.
	•Provision expense of $37 million relates to portfolio mix changes and credit migration trends.
	•Non-performing assets to total assets was 0.20% compared to 0.15% at June 30, 2023.
Capital	•Estimated total risk-based capital ratio of 11.5% and estimated common equity tier 1 risk-based capital ratio of 9.4%.
	•Declared a quarterly cash dividend of $0.36 per common share on August 14, 2023, which was paid September 11, 2023.
Notable items	•Sold $159 million in non-relationship jumbo residential mortgage loans that were marked to fair value at merger close.
	•Completed the sale of approximately one-third of the MSR portfolio.
	•Incurred $19 million in merger-related expense.

3Q23 KEY FINANCIAL DATA
PERFORMANCE METRICS	3Q23		2Q23		3Q22
Return on average assets	1.02%		1.00%		1.09%
Return on average common equity	11.07%		10.84%		12.99%
Return on average tangible common equity 1	16.93%		16.63%		13.02%
Operating return on average assets 1	1.23%		1.27%		1.33%
Operating return on average common equity 1	13.40%		13.77%		15.86%
Operating return on average tangible common equity 1	20.48%		21.13%		15.90%
Net interest margin	3.91%		3.93%		3.88%
Efficiency ratio	57.82%		62.60%		56.07%
INCOME STATEMENT ($ in 000s, excl. per share data)	3Q23		2Q23		3Q22
Net interest income	$480,875		$483,975		$287,604
Provision for credit losses	$36,737		$16,014		$27,572
Non-interest income	$43,981		$39,678		$29,445
Non-interest expense	$304,147		$328,559		$177,964
Pre-provision net revenue 1	$220,709		$195,094		$139,085
Operating pre-provision net revenue1	$258,687		$243,114		$163,793
Earnings per common share - diluted 2	$0.65		$0.64		$0.65
Operating earnings per common share - diluted 1,2	$0.79		$0.81		$0.79
Dividends paid per share 2	$0.36		$0.36		$0.35
BALANCE SHEET	3Q23		2Q23		3Q22
Total assets	$52.0	B	$53.6	B	$31.5	B
Loans and leases	$37.2	B	$37.0	B	$25.5	B
Total deposits	$41.6	B	$40.8	B	$26.8	B
Book value per common share 2	$22.21		$23.16		$18.69
Tangible book value per share1,2	$14.22		$15.02		$18.65

Investor Contact

Jacquelynne "Jacque" Bohlen, SVP/Investor Relations Director, 503-727-4117, jacquebohlen@umpquabank.com

1 "Non-GAAP" financial measure. See GAAP to Non-GAAP Reconciliation for the comparable GAAP measurement.

2 Periods prior to February 28, 2023, have been restated as a result of the adjustment to common shares outstanding based on the exchange ratio from the UHC merger of 0.5958.

Columbia Banking System, Inc. Reports Third Quarter 2023 Results

October 18, 2023

Page 2

Organizational Update

Columbia Banking System, Inc. ("Columbia", "we", or "our") has completed substantially all integration priorities, driving the realization of $140 million in annualized net merger-related cost-savings as of September 30, 2023, outpacing the $135 million target communicated when the combination was announced. Further, Umpqua Bank, the primary subsidiary of Columbia, continued to expand its presence in Utah with the opening of its first branch in the state during the third quarter.

On February 28, 2023, Columbia completed its merger with Umpqua Holdings Corporation ("UHC"), combining the two premier banks in the Northwest to create one of the largest banks headquartered in the West (the "merger"). Columbia's financial results for any periods ended prior to February 28, 2023 reflect UHC results only on a standalone basis. In addition, Columbia's reported financial results for the first quarter of 2023 reflect UHC financial results only until the closing of the merger after the close of business on February 28, 2023. As a result of these two factors, Columbia's financial results for the first, second, and third quarters of 2023 and the nine months ended September 30, 2023 may not be directly comparable to prior reported periods. The number of shares issued and outstanding, earnings per share, additional paid-in capital, and all references to share quantities or metrics of Columbia have been retrospectively restated to reflect the equivalent number of shares issued in the merger as the merger was treated as a reverse merger. Under the reverse acquisition method of accounting, the assets and liabilities of Columbia as of February 28, 2023 ("historical Columbia") were recorded at their respective fair values.

Net Interest Income

Net interest income was $481 million for the third quarter of 2023, down $3 million from the prior quarter. The slight decline reflects higher interest income given expanded earning asset yields that were more than offset by higher funding costs.

Columbia's net interest margin was 3.91% for the third quarter of 2023, down 2 basis points from 3.93% for the second quarter of 2023. The second full quarter as a combined organization, higher customer balances, and consistent purchase accounting trends contributed to net interest margin stabilization between quarters. The cost of interest-bearing deposits increased 37 basis points on a linked-quarter basis to 2.01% for the third quarter of 2023, which compares to 2.18% for the month of September and 2.27% at September 30, 2023. Deposit costs were impacted by the decision to replace a portion of maturing FHLB advances with brokered deposits during the third quarter, which increased our cost of deposits but was fairly neutral to our cost of interest-bearing liabilities. Columbia's cost of interest-bearing liabilities increased 27 basis points on a linked-quarter basis to 2.72% for the third quarter of 2023, which compares to 2.77% for the month of September and 2.78% at September 30, 2023. Please refer to the Q3 2023 Earnings Presentation for additional net interest margin change details and interest rate sensitivity information as well as to our non-GAAP disclosures in this press release for the impact of purchase accounting accretion and amortization on individual line items.

Non-interest Income

Non-interest income was $44 million for the third quarter of 2023, up $4 million from the prior quarter. Higher customer-related fee income, loan gain-on-sale income from select portfolio sales, and a smaller loss related to fair value adjustments and mortgage servicing rights ("MSR") hedging activity drove the increase. A net fair value loss of $15 million in the third quarter compares to a net fair value loss of $16 million in the second quarter, as detailed in our non-GAAP disclosures. As previously communicated, Columbia entered an agreement to sell approximately one-third of its MSR portfolio that relates to a non-relationship component of the serviced loan portfolio. The transaction closed in late September without any income statement impact.

Non-interest Expense

Non-interest expense was $304 million for the third quarter of 2023, down $24 million from the prior quarter level. The decrease reflects the realization of cost savings as well as an $11 million decline in merger-related expense, which were $19 million in the third quarter. Please refer to the Q3 2023 Earnings Presentation for additional expense details, including an update on realized merger-related cost-savings through September 30, 2023.

Balance Sheet

Total consolidated assets were $52.0 billion as of September 30, 2023, compared to $53.6 billion as of June 30, 2023. Cash and cash equivalents was $2.4 billion as of September 30, 2023, a decrease of $1.0 billion relative to June 30, 2023. We reduced our cash position during the third quarter given stabilizing industry trends and ample sources of available liquidity. Excess cash was used to pay off maturing FHLB advances, which declined to $4.0 billion as of September 30, 2023, compared to $6.3 billion as of June 30, 2023. Including secured off-balance sheet lines of credit, total available liquidity was $19.1 billion as of September 30, 2023, representing 37% of total assets, 46% of total deposits, and 142% of uninsured deposits. Please refer to the Q3 2023 Earnings Presentation for additional details related to our liquidity position.

Columbia Banking System, Inc. Reports Third Quarter 2023 Results

October 18, 2023

Page 3

Available for sale securities, which are held on balance sheet at fair value, were $8.5 billion as of September 30, 2023, a decrease of $494 million relative to June 30, 2023, as paydowns and a decline in the fair value of the portfolio were only partially offset by accretion of the discount on historical Columbia securities. Please refer to the Q3 2023 Earnings Presentation for additional details related to our securities portfolio.

Gross loans and leases were $37.2 billion as of September 30, 2023, an increase of $121 million relative to June 30, 2023, as organic growth during the quarter more than offset the sale of $159 million in non-relationship jumbo residential mortgage loans that were marked to fair value at merger close. "We continued to selectively prune the portfolio during the third quarter, bringing the transfer and sale of loans that were transactional in nature to approximately $650 million over the past two quarters," commented Tory Nixon, President of Umpqua Bank. "Higher outstanding commercial line balances and other relationship-driven expansion contributed to 3% annualized loan growth in the third quarter when loan sales are excluded." Please refer to the Q3 2023 Earnings Presentation for additional details related to our loan portfolio, which include underwriting characteristics, the composition of our commercial portfolios, and disclosure related to our office portfolio.

Total deposits were $41.6 billion as of September 30, 2023, an increase of $789 million relative to June 30, 2023. "Customer deposit balances stabilized during the third quarter, increasing slightly between September and June," stated Mr. Nixon. "While market liquidity tightening, the impact of inflation on customer spending, and businesses' use of cash continue to impact our deposit flows, our teams' focus on balancing deposit generation alongside other growth resulted in net deposit increases throughout many business lines." Please refer to the Q3 2023 Earnings Presentation for additional details related to deposit characteristics and flows.

Credit Quality

The allowance for credit losses was $438 million, or 1.18% of loans and leases, as of September 30, 2023, compared to $424 million, or 1.15% of loans and leases, as of June 30, 2023. The provision for credit losses was $37 million for the third quarter of 2023 and reflects portfolio mix changes and credit migration trends. Please refer to the Q3 2023 Earnings Presentation for additional details related to the allowance for credit losses and other credit trends.

Net charge-offs were 0.25% of average loans and leases (annualized) for the third quarter of 2023, compared to 0.30% for the second quarter of 2023. Net charge-off activity continued to be centered in the FinPac portfolio, which experienced a decline in charge-offs. Bank charge-off activity remained low at 0.01% of average bank loans. As of September 30, 2023, non-performing assets were $106 million, or 0.20% of total assets, compared to $80 million, or 0.15% as of June 30, 2023.

Capital

As of September 30, 2023, Columbia's book value per common share decreased to $22.21, compared to $23.16 at June 30, 2023. The linked-quarter change in book value primarily reflects a change in accumulated other comprehensive (loss) income ("AOCI") to $(680) million at September 30, 2023, compared to $(419) million at the prior quarter-end. The change in AOCI is due primarily to an increase in the tax-effected net unrealized loss on available for sale securities to $650 million as of September 30, 2023, compared to $403 million as of June 30, 2023. Tangible book value per common share3 decreased to $14.22, compared to $15.02 at June 30, 2023.

Columbia's estimated total risk-based capital ratio was 11.5% and its estimated common equity tier 1 risk-based capital ratio was 9.4% as of September 30, 2023, compared to 11.3% and 9.2%, respectively, at June 30, 2023. Columbia remains above current “well-capitalized” regulatory minimums. "We continued to build capital during the quarter through organic earnings generation and the realization of loan and investment securities discount accretion," stated Ron Farnsworth, Chief Financial Officer of Columbia. "We expect our capital position to continue to build over time, supporting our growing franchise and increasing flexibility for capital return." The regulatory capital ratios as of September 30, 2023 are estimates, pending completion and filing of Columbia's regulatory reports.

3 "Non-GAAP" financial measure. See GAAP to Non-GAAP Reconciliation for the comparable GAAP measurement.

Columbia Banking System, Inc. Reports Third Quarter 2023 Results

October 18, 2023

Page 4

Earnings Presentation and Conference Call Information

Columbia's Q3 2023 Earnings Presentation provides additional disclosure. A copy will be available on our investor relations page: www.columbiabankingsystem.com.

Columbia will host its third quarter 2023 earnings conference call on October 18, 2023, at 2:00 p.m. PT (5:00 p.m. ET). During the call, Columbia's management will provide an update on recent activities and discuss its third quarter 2023 financial results. Participants may register for the call using the below link to receive dial-in details and their own unique PINs or join the audiocast. It is recommended you join 10 minutes prior to the start time.

Register for the call:https://register.vevent.com/register/BIcd18f9ce2ec34fdf915aa619af3a3d01

Join the audiocast:https://edge.media-server.com/mmc/p/ih23hqkg/

Access the replay through Columbia's investor relations page:www.columbiabankingsystem.com

About Columbia Banking System, Inc.

Columbia (Nasdaq: COLB) is headquartered in Tacoma, Washington and is the parent company of Umpqua Bank, an award-winning western U.S. regional bank based in Lake Oswego, Oregon. In March of 2023, Columbia and Umpqua combined two of the Pacific Northwest's premier financial institutions under the Umpqua Bank brand to create one of the largest banks headquartered in the West and a top-30 U.S. bank. With over $50 billion of assets, Umpqua Bank combines the resources, sophistication and expertise of a national bank with a commitment to deliver personalized service at scale. The bank operates in Arizona, California, Colorado, Idaho, Nevada, Oregon, Utah, and Washington and supports consumers and businesses through a full suite of services, including retail and commercial banking; Small Business Administration lending; institutional and corporate banking; and equipment leasing. Umpqua Bank customers also have access to comprehensive investment and wealth management expertise as well as healthcare and private banking through Columbia Wealth Management and Columbia Trust Company, a subsidiary of Columbia. Learn more at www.columbiabankingsystem.com.

Forward-Looking Statements

This press release 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. These statements are necessarily subject to risk and uncertainty and actual results could differ materially due to various risk factors, including those set forth from time to time in our filings with the Securities and Exchange Commission (the "SEC"). You should not place undue reliance on forward-looking statements and we undertake no obligation to update any such statements. Forward-looking statements can be identified by words such as "anticipates," "intends," "plans," "seeks," "believes," "estimates," "expects," "target," "projects," "outlook," "forecast," "will," "may," "could," "should," "can" and similar references to future periods. In this press release we make forward-looking statements about strategic and growth initiatives and the result of such activity. Risks that could cause results to differ from forward-looking statements we make include, without limitation: current and future economic and market conditions, including the effects of declines in housing and commercial real estate prices, high unemployment rates, continued inflation and any recession or slowdown in economic growth particularly in the western United States; economic forecast variables that are either materially worse or better than end of quarter projections and deterioration in the economy that could result in increased loan and lease losses, especially those risks associated with concentrations in real estate related loans; our ability to effectively manage problem credits; the impact of bank failures or adverse developments at or news developments concerning other banks on general investor sentiment regarding the liquidity and stability of banks; changes in interest rates that could significantly reduce net interest income and negatively affect asset yields and valuations and funding sources; changes in the scope and cost of FDIC insurance and other coverage; our ability to successfully implement efficiency and operational excellence initiatives; our ability to successfully develop and market new products and technology; changes in laws or regulations; any failure to realize the anticipated benefits of the UHC merger when expected or at all; the possibility that the integration following the UHC merger may be more expensive than anticipated, including as a result of unexpected factors or events, diversion of management’s attention from ongoing business operations and opportunities; potential adverse reactions or changes to business or employee relationships, including those resulting from the completion of the UHC merger and integration of the companies; the effect of geopolitical instability, including wars, conflicts and terrorist attacks; and natural disasters and other similar unexpected events outside of our control. We also caution that the amount and timing of any future common stock dividends or repurchases will depend on the earnings, cash requirements and financial condition of Columbia, market conditions, capital requirements, applicable law and regulations (including federal securities laws and federal banking regulations), and other factors deemed relevant by Columbia's Board of Directors, and may be subject to regulatory approval or conditions.

Columbia Banking System, Inc. Reports Third Quarter 2023 Results

October 18, 2023

Page 5

TABLE INDEX
	Page
Consolidated Statements of Operations	6
Consolidated Balance Sheets	8
Financial Highlights	9
Loan & Lease Portfolio Balances and Mix	11
Deposit Portfolio Balances and Mix	12
Credit Quality - Non-performing Assets	13
Credit Quality - Allowance for Credit Losses	14
Consolidated Average Balance Sheets, Net Interest Income, and Yields/Rates	16
Residential Mortgage Banking Activity	18
GAAP to Non-GAAP Reconciliation	20

Columbia Banking System, Inc. Reports Third Quarter 2023 Results

October 18, 2023

Page 6

Columbia Banking System, Inc.
Consolidated Statements of Operations
(Unaudited)
	Quarter Ended										% Change
($ in thousands, except per share data)	Sep 30, 2023		Jun 30, 2023		Mar 31, 2023		Dec 31, 2022		Sep 30, 2022		Seq. Quarter		Year over Year
Interest income:
Loans and leases	$	569,670	$	552,679	$	413,525	$	322,350	$	278,830	3	%	104	%
Interest and dividends on investments:
Taxable	80,066		79,036		39,729		18,108		18,175		1	%	341	%
Exempt from federal income tax	6,929		6,817		3,397		1,288		1,322		2	%	424	%
Dividends	4,941		2,581		719		182		86		91	%	nm
Temporary investments and interest bearing deposits	34,407		34,616		18,581		10,319		5,115		(1)	%	nm
Total interest income	696,013		675,729		475,951		352,247		303,528		3	%	129	%
Interest expense:
Deposits	126,974		100,408		63,613		31,174		9,090		26	%	nm
Securities sold under agreement to repurchase and federal funds purchased	1,220		1,071		406		323		545		14	%	124	%
Borrowings	77,080		81,004		28,764		8,023		798		(5)	%	nm
Junior and other subordinated debentures	9,864		9,271		8,470		7,248		5,491		6	%	80	%
Total interest expense	215,138		191,754		101,253		46,768		15,924		12	%	nm
Net interest income	480,875		483,975		374,698		305,479		287,604		(1)	%	67	%
Provision for credit losses	36,737		16,014		105,539		32,948		27,572		129	%	33	%
Non-interest income:
Service charges on deposits	17,410		16,454		14,312		12,139		12,632		6	%	38	%
Card-based fees	15,674		13,435		11,561		9,017		9,115		17	%	72	%
Financial services and trust revenue	4,651		4,512		1,297		25		27		3	%	nm
Residential mortgage banking revenue (loss), net	7,103		(2,342)		7,816		(1,812)		17,341		nm		(59)	%
Gain on sale of debt securities, net	4		—		—		—		—		nm		nm
(Loss) gain on equity securities, net	(2,055)		(697)		2,416		284		(2,647)		195	%	(22)	%
Gain on loan and lease sales, net	1,871		442		940		1,531		1,525		323	%	23	%
BOLI income	4,440		4,063		2,790		2,033		2,023		9	%	119	%
Other (loss) income	(5,117)		3,811		13,603		11,662		(10,571)		(234)	%	(52)	%
Total non-interest income	43,981		39,678		54,735		34,879		29,445		11	%	49	%
Non-interest expense:
Salaries and employee benefits	159,041		163,398		136,092		107,982		109,164		(3)	%	46	%
Occupancy and equipment, net	43,070		50,550		41,700		34,021		35,042		(15)	%	23	%
Intangible amortization	29,879		35,553		12,660		1,019		1,025		(16)	%	nm
FDIC assessments	11,200		11,579		6,113		3,487		3,007		(3)	%	272	%
Merger related expense	18,938		29,649		115,898		11,637		769		(36)	%	nm
Other expenses	42,019		37,830		30,355		36,836		28,957		11	%	45	%
Total non-interest expense	304,147		328,559		342,818		194,982		177,964		(7)	%	71	%
Income (loss) before provision (benefit) for income taxes	183,972		179,080		(18,924)		112,428		111,513		3	%	65	%
Provision (benefit) for income taxes	48,127		45,703		(4,886)		29,464		27,473		5	%	75	%
Net income (loss)	$	135,845	$	133,377	$	(14,038)	$	82,964	$	84,040	2	%	62	%
Weighted average basic shares outstanding (1)	208,070		207,977		156,383		129,321		129,319		0	%	61	%
Weighted average diluted shares outstanding (1)	208,645		208,545		156,383		129,801		129,733		0	%	61	%
Earnings (loss) per common share – basic (1)	$	0.65	$	0.64	$	(0.09)	$	0.64	$	0.65	2	%	0	%
Earnings (loss) per common share – diluted (1)	$	0.65	$	0.64	$	(0.09)	$	0.64	$	0.65	2	%	0	%
nm = not meaningful

(1) Periods prior to February 28, 2023, have been restated as a result of the adjustment to common shares outstanding based on the exchange ratio from the UHC merger of 0.5958.

Columbia Banking System, Inc. Reports Third Quarter 2023 Results

October 18, 2023

Page 7

Columbia Banking System, Inc.
Consolidated Statements of Operations
(Unaudited)
	Nine Months Ended				% Change
($ in thousands, except per share data)	Sep 30, 2023		Sep 30, 2022		Year over Year
Interest income:
Loans and leases	$	1,535,874	$	727,908	111	%
Interest and dividends on investments:
Taxable	198,831		54,156		267	%
Exempt from federal income tax	17,143		4,063		322	%
Dividends	8,241		256		nm
Temporary investments and interest bearing deposits	87,604		9,387		nm
Total interest income	1,847,693		795,770		132	%
Interest expense:
Deposits	290,995		17,021		nm
Securities sold under agreement to repurchase and federal funds purchased	2,697		674		300	%
Borrowings	186,848		897		nm
Junior and other subordinated debentures	27,605		12,641		118	%
Total interest expense	508,145		31,233		nm
Net interest income	1,339,548		764,537		75	%
Provision for credit losses	158,290		51,068		210	%
Non-interest income:
Service charges on deposits	48,176		36,226		33	%
Card-based fees	40,670		28,353		43	%
Brokerage revenue	10,460		65		nm
Residential mortgage banking revenue, net	12,577		108,671		(88)	%
Gain on sale of debt securities, net	4		2		100	%
Loss on equity securities, net	(336)		(7,383)		(95)	%
Gain on loan and lease sales, net	3,253		5,165		(37)	%
BOLI income	11,293		6,220		82	%
Other income (loss)	12,297		(12,670)		nm
Total non-interest income	138,394		164,649		(16)	%
Non-interest expense:
Salaries and employee benefits	458,531		333,244		38	%
Occupancy and equipment, net	135,320		104,430		30	%
Intangible amortization	78,092		3,076		nm
FDIC assessments	28,892		10,477		176	%
Merger related expense	164,485		5,719		nm
Other expenses	110,204		83,022		33	%
Total non-interest expense	975,524		539,968		81	%
Income before provision for income taxes	344,128		338,150		2	%
Provision for income taxes	88,944		84,362		5	%
Net income	$	255,184	$	253,788	1	%
Weighted average basic shares outstanding (1)	190,997		129,262		48	%
Weighted average diluted shares outstanding (1)	191,546		129,702		48	%
Earnings per common share – basic (1)	$	1.34	$	1.96	(32)	%
Earnings per common share – diluted (1)	$	1.33	$	1.96	(32)	%
nm = not meaningful

(1) Periods prior to February 28, 2023, have been restated as a result of the adjustment to common shares outstanding based on the exchange ratio from the UHC merger of 0.5958.

Columbia Banking System, Inc. Reports Third Quarter 2023 Results

October 18, 2023

Page 8

Columbia Banking System, Inc. Consolidated Balance Sheets
(Unaudited)
											% Change
($ in thousands, except per share data)	Sep 30, 2023		Jun 30, 2023		Mar 31, 2023		Dec 31, 2022		Sep 30, 2022		Seq. Quarter		Year over Year
Assets:
Cash and due from banks	$	492,474	$	538,653	$	555,919	$	327,313	$	321,447	(9)	%	53	%
Interest bearing cash and temporary investments	1,911,221		2,868,563		3,079,266		967,330		1,232,412		(33)	%	55	%
Investment securities:
Equity and other, at fair value	73,638		76,361		76,532		72,959		72,277		(4)	%	2	%
Available for sale, at fair value	8,503,986		8,998,428		9,249,600		3,196,166		3,136,391		(5)	%	171	%
Held to maturity, at amortized cost	2,344		2,388		2,432		2,476		2,547		(2)	%	(8)	%
Loans held for sale	60,313		183,633		49,338		71,647		148,275		(67)	%	(59)	%
Loans and leases	37,170,598		37,049,299		37,091,280		26,155,981		25,507,951		0	%	46	%
Allowance for credit losses on loans and leases	(416,560)		(404,603)		(417,464)		(301,135)		(283,065)		3	%	47	%
Net loans and leases	36,754,038		36,644,696		36,673,816		25,854,846		25,224,886		0	%	46	%
Restricted equity securities	168,524		258,524		246,525		47,144		40,993		(35)	%	311	%
Premises and equipment, net	337,855		368,698		375,190		176,016		165,305		(8)	%	104	%
Operating lease right-of-use assets	114,220		119,255		127,296		78,598		81,729		(4)	%	40	%
Goodwill	1,029,234		1,029,234		1,030,142		—		—		0	%	nm
Other intangible assets, net	636,883		666,762		702,315		4,745		5,764		(4)	%	nm
Residential mortgage servicing rights, at fair value	117,640		172,929		178,800		185,017		196,177		(32)	%	(40)	%
Bank owned life insurance	648,232		643,727		641,922		331,759		329,699		1	%	97	%
Deferred tax asset, net	469,841		362,880		351,229		132,823		128,120		29	%	267	%
Other assets	669,150		657,365		653,904		399,800		385,938		2	%	73	%
Total assets	$	51,989,593	$	53,592,096	$	53,994,226	$	31,848,639	$	31,471,960	(3)	%	65	%
Liabilities:
Deposits
Non-interest bearing	$	15,532,948	$	16,019,408	$	17,215,781	$	10,288,849	$	11,246,358	(3)	%	38	%
Interest bearing	26,091,420		24,815,509		24,370,566		16,776,763		15,570,749		5	%	68	%
Total deposits	41,624,368		40,834,917		41,586,347		27,065,612		26,817,107		2	%	55	%
Securities sold under agreements to repurchase	258,383		294,914		271,047		308,769		383,569		(12)	%	(33)	%
Borrowings	3,985,000		6,250,000		5,950,000		906,175		756,214		(36)	%	427	%
Junior subordinated debentures, at fair value	331,545		312,872		297,721		323,639		325,744		6	%	2	%
Junior and other subordinated debentures, at amortized cost	107,952		108,009		108,066		87,813		87,870		0	%	23	%
Operating lease liabilities	129,845		132,099		140,648		91,694		95,512		(2)	%	36	%
Other liabilities	920,338		831,097		755,674		585,111		588,430		11	%	56	%
Total liabilities	47,357,431		48,763,908		49,109,503		29,368,813		29,054,446		(3)	%	63	%
Shareholders' equity:
Common stock	5,798,167		5,792,792		5,788,553		3,450,493		3,448,007		0	%	68	%
Accumulated deficit	(485,576)		(545,842)		(603,696)		(543,803)		(580,933)		(11)	%	(16)	%
Accumulated other comprehensive loss	(680,429)		(418,762)		(300,134)		(426,864)		(449,560)		62	%	51	%
Total shareholders' equity	4,632,162		4,828,188		4,884,723		2,479,826		2,417,514		(4)	%	92	%
Total liabilities and shareholders' equity	$	51,989,593	$	53,592,096	$	53,994,226	$	31,848,639	$	31,471,960	(3)	%	65	%
Common shares outstanding at period end (1)	208,575		208,514		208,429		129,321		129,320		0	%	61	%
nm = not meaningful

(1) Periods prior to February 28, 2023, have been restated as a result of the adjustment to common shares outstanding based on the exchange ratio from the UHC merger of 0.5958.

Columbia Banking System, Inc. Reports Third Quarter 2023 Results

October 18, 2023

Page 9

Columbia Banking System, Inc.
Financial Highlights
(Unaudited)
	Quarter Ended															% Change
	Sep 30, 2023			Jun 30, 2023			Mar 31, 2023			Dec 31, 2022			Sep 30, 2022			Seq. Quarter		Year over Year
Per Common Share Data: (5)
Dividends (5)	$	0.36		$	0.36		$	0.35		$	0.35		$	0.35		0	%	3	%
Book value (5)	$	22.21		$	23.16		$	23.44		$	19.18		$	18.69		(4)	%	19	%
Tangible book value (1),(5)	$	14.22		$	15.02		$	15.12		$	19.14		$	18.65		(5)	%	(24)	%
Performance Ratios:
Efficiency ratio (2)	57.82		%	62.60		%	79.71		%	57.24		%	56.07		%	(4.78)		1.75
Return on average assets ("ROAA")	1.02		%	1.00		%	(0.14)		%	1.04		%	1.09		%	0.02		(0.07)
Pre-provision net revenue ("PPNR") ROAA (1)	1.65		%	1.46		%	0.89		%	1.82		%	1.80		%	0.19		(0.15)
Return on average common equity	11.07		%	10.84		%	(1.70)		%	13.50		%	12.99		%	0.23		(1.92)
Return on average tangible common equity (1)	16.93		%	16.63		%	(2.09)		%	13.53		%	13.02		%	0.30		3.91
Performance Ratios - Operating: (1)
Operating efficiency ratio (1),(2)	51.97		%	54.85		%	53.46		%	52.01		%	51.72		%	(2.88)		0.25
Operating return on average assets (1)	1.23		%	1.27		%	0.74		%	1.24		%	1.33		%	(0.04)		(0.10)
Operating PPNR return on average assets (1)	1.94		%	1.82		%	2.01		%	2.10		%	2.12		%	0.12		(0.18)
Operating return on average common equity (1)	13.40		%	13.77		%	8.66		%	16.14		%	15.86		%	(0.37)		(2.46)
Operating return on average tangible common equity (1)	20.48		%	21.13		%	10.64		%	16.18		%	15.90		%	(0.65)		4.58
Average Balance Sheet Yields, Rates, & Ratios:
Yield on loans and leases	6.08		%	5.95		%	5.55		%	4.92		%	4.41		%	0.13		1.67
Yield on earning assets (2)	5.65		%	5.48		%	5.19		%	4.62		%	4.10		%	0.17		1.55
Cost of interest bearing deposits	2.01		%	1.64		%	1.32		%	0.77		%	0.23		%	0.37		1.78
Cost of interest bearing liabilities	2.72		%	2.45		%	1.82		%	1.05		%	0.39		%	0.27		2.33
Cost of total deposits	1.23		%	0.99		%	0.80		%	0.46		%	0.14		%	0.24		1.09
Cost of total funding (3)	1.81		%	1.61		%	1.16		%	0.65		%	0.23		%	0.20		1.58
Net interest margin (2)	3.91		%	3.93		%	4.08		%	4.01		%	3.88		%	(0.02)		0.03
Average interest bearing cash / Average interest earning assets	5.17		%	5.47		%	4.33		%	3.62		%	3.04		%	(0.30)		2.13
Average loans and leases / Average interest earning assets	75.64		%	75.18		%	80.96		%	85.32		%	84.54		%	0.46		(8.90)
Average loans and leases / Average total deposits	90.63		%	90.98		%	93.01		%	95.85		%	93.55		%	(0.35)		(2.92)
Average non-interest bearing deposits / Average total deposits	38.55		%	40.05		%	39.55		%	40.30		%	42.29		%	(1.50)		(3.74)
Average total deposits / Average total funding (3)	86.66		%	85.59		%	91.36		%	94.52		%	96.34		%	1.07		(9.68)
Select Credit & Capital Ratios:
Non-performing loans and leases to total loans and leases	0.28		%	0.22		%	0.20		%	0.22		%	0.20		%	0.06		0.08
Non-performing assets to total assets	0.20		%	0.15		%	0.14		%	0.18		%	0.16		%	0.05		0.04
Allowance for credit losses to loans and leases	1.18		%	1.15		%	1.18		%	1.21		%	1.16		%	0.03		0.02
Total risk-based capital ratio (4)	11.5		%	11.3		%	10.9		%	13.7		%	13.2		%	0.20		(1.70)
Common equity tier 1 risk-based capital ratio (4)	9.4		%	9.2		%	8.9		%	11.0		%	10.7		%	0.20		(1.30)

(1) See GAAP to Non-GAAP Reconciliation.

(2) Tax exempt interest has been adjusted to a taxable equivalent basis using a 21% tax rate.

(3) Total funding = Total deposits + Total borrowings.

(4) Estimated holding company ratios.

(5) Periods prior to February 28, 2023, have been restated as a result of the adjustment to common shares outstanding based on the exchange ratio from the UHC merger of 0.5958.

Columbia Banking System, Inc. Reports Third Quarter 2023 Results

October 18, 2023

Page 10

Columbia Banking System, Inc.
Financial Highlights
(Unaudited)
	Nine Months Ended						% Change
	Sep 30, 2023			Sep 30, 2022			Year over Year
Per Common Share Data: (4)
Dividends (4)	$	1.07		$	1.05		1.90	%
Performance Ratios:
Efficiency ratio (2)	65.87		%	58.05		%	7.82
Return on average assets	0.70		%	1.11		%	(0.41)
PPNR return on average assets (1)	1.38		%	1.70		%	(0.32)
Return on average common equity	7.77		%	12.94		%	(5.17)
Return on average tangible common equity (1)	11.21		%	12.98		%	(1.77)
Performance Ratios - Operating: (1)
Operating efficiency ratio (1),(2)	53.43		%	57.03		%	(3.60)
Operating return on average assets (1)	1.11		%	1.14		%	(0.03)
Operating PPNR return on average assets (1)	1.91		%	1.74		%	0.17
Operating return on average common equity (1)	12.34		%	13.28		%	(0.94)
Operating return on average tangible common equity (1)	17.80		%	13.32		%	4.48
Average Balance Sheet Yields, Rates, & Ratios:
Yield on loans and leases	5.88		%	4.06		%	1.82
Yield on earning assets (2)	5.46		%	3.62		%	1.84
Cost of interest bearing deposits	1.68		%	0.15		%	1.53
Cost of interest bearing liabilities	2.38		%	0.26		%	2.12
Cost of total deposits	1.02		%	0.09		%	0.93
Cost of total funding (3)	1.56		%	0.15		%	1.41
Net interest margin (2)	3.96		%	3.48		%	0.48
Average interest bearing cash / Average interest earning assets	5.05		%	5.87		%	(0.82)
Average loans and leases / Average interest earning assets	76.91		%	80.80		%	(3.89)
Average loans and leases / Average total deposits	91.42		%	89.21		%	2.21
Average non-interest bearing deposits / Average total deposits	39.28		%	41.89		%	(2.61)
Average total deposits / Average total funding (3)	87.53		%	96.61		%	(9.08)

(1) See GAAP to Non-GAAP Reconciliation.

(2) Tax exempt interest has been adjusted to a taxable equivalent basis using a 21% tax rate.

(3) Total funding = Total deposits + Total borrowings.

(4) Periods prior to February 28, 2023, have been restated as a result of the adjustment to common shares outstanding based on the exchange ratio from the UHC merger of 0.5958.

Columbia Banking System, Inc. Reports Third Quarter 2023 Results

October 18, 2023

Page 11

Columbia Banking System, Inc.
Loan & Lease Portfolio Balances and Mix
(Unaudited)
	Sep 30, 2023			Jun 30, 2023			Mar 31, 2023			Dec 31, 2022			Sep 30, 2022			% Change
($ in thousands)	Amount			Amount			Amount			Amount			Amount			Seq. Quarter		Year over Year
Loans and leases:
Commercial real estate:
Non-owner occupied term, net	$	6,490,638		$	6,434,673		$	6,353,550		$	3,894,840		$	3,846,426		1	%	69	%
Owner occupied term, net	5,235,227			5,254,401			5,156,848			2,567,761			2,549,761			0	%	105	%
Multifamily, net	5,684,495			5,622,875			5,590,587			5,285,791			5,090,661			1	%	12	%
Construction & development, net	1,669,918			1,528,924			1,467,561			1,077,346			1,036,931			9	%	61	%
Residential development, net	354,922			388,641			440,667			200,838			205,935			(9)	%	72	%
Commercial:
Term, net	5,437,915			5,449,787			5,906,774			3,029,547			3,003,424			0	%	81	%
Lines of credit & other, net	2,353,548			2,268,790			2,184,762			960,054			914,507			4	%	157	%
Leases & equipment finance, net	1,728,991			1,740,037			1,746,267			1,706,172			1,669,817			(1)	%	4	%
Residential:
Mortgage, net	6,121,838			6,272,898			6,187,964			5,647,035			5,470,624			(2)	%	12	%
Home equity loans & lines, net	1,899,948			1,898,958			1,870,002			1,631,965			1,565,094			0	%	21	%
Consumer & other, net	193,158			189,315			186,298			154,632			154,771			2	%	25	%
Total loans and leases, net of deferred fees and costs	$	37,170,598		$	37,049,299		$	37,091,280		$	26,155,981		$	25,507,951		0	%	46	%
Loans and leases mix:
Commercial real estate:
Non-owner occupied term, net	17		%	17		%	16		%	15		%	15		%
Owner occupied term, net	14		%	14		%	14		%	10		%	10		%
Multifamily, net	15		%	15		%	15		%	20		%	20		%
Construction & development, net	4		%	4		%	4		%	4		%	4		%
Residential development, net	1		%	1		%	1		%	1		%	1		%
Commercial:
Term, net	15		%	15		%	16		%	12		%	12		%
Lines of credit & other, net	6		%	6		%	6		%	4		%	4		%
Leases & equipment finance, net	5		%	5		%	5		%	6		%	6		%
Residential:
Mortgage, net	17		%	17		%	17		%	21		%	21		%
Home equity loans & lines, net	5		%	5		%	5		%	6		%	6		%
Consumer & other, net	1		%	1		%	1		%	1		%	1		%
Total	100		%	100		%	100		%	100		%	100		%

Columbia Banking System, Inc. Reports Third Quarter 2023 Results

October 18, 2023

Page 12

Columbia Banking System, Inc.
Deposit Portfolio Balances and Mix
(Unaudited)
	Sep 30, 2023			Jun 30, 2023			Mar 31, 2023			Dec 31, 2022			Sep 30, 2022			% Change
($ in thousands)	Amount			Amount			Amount			Amount			Amount			Seq. Quarter		Year over Year
Deposits:
Demand, non-interest bearing	$	15,532,948		$	16,019,408		$	17,215,781		$	10,288,849		$	11,246,358		(3)	%	38	%
Demand, interest bearing	6,898,831			6,300,082			5,900,462			4,080,469			3,903,746			10	%	77	%
Money market	10,349,217			10,115,908			10,681,422			7,721,011			7,601,506			2	%	36	%
Savings	3,018,706			3,171,714			3,469,112			2,265,052			2,455,917			(5)	%	23	%
Time	5,824,666			5,227,805			4,319,570			2,710,231			1,609,580			11	%	262	%
Total	$	41,624,368		$	40,834,917		$	41,586,347		$	27,065,612		$	26,817,107		2	%	55	%
Total core deposits (1)	$	37,597,830		$	37,639,368		$	39,155,298		$	25,616,010		$	26,292,548		0	%	43	%
Deposit mix:
Demand, non-interest bearing	37		%	39		%	41		%	38		%	42		%
Demand, interest bearing	17		%	15		%	14		%	15		%	15		%
Money market	25		%	25		%	26		%	29		%	28		%
Savings	7		%	8		%	9		%	8		%	9		%
Time	14		%	13		%	10		%	10		%	6		%
Total	100		%	100		%	100		%	100		%	100		%

(1) Core deposits are defined as total deposits less time deposits greater than $250,000 and all brokered deposits.

Columbia Banking System, Inc. Reports Third Quarter 2023 Results

October 18, 2023

Page 13

	Columbia Banking System, Inc.
	Credit Quality – Non-performing Assets
	(Unaudited)
		Quarter Ended															% Change
($ in thousands)		Sep 30, 2023			Jun 30, 2023			Mar 31, 2023			Dec 31, 2022			Sep 30, 2022			Seq. Quarter		Year over Year
Non-performing assets:
Loans and leases on non-accrual status:
	Commercial real estate, net	$	26,053		$	10,994		$	15,612		$	5,011		$	5,403		137	%	382	%
	Commercial, net	44,341			39,316			42,301			25,691			18,652			13	%	138	%
	Residential, net	—			—			—			—			—			nm		nm
	Consumer & other, net	—			—			—			—			—			nm		nm
	Total loans and leases on non-accrual status	70,394			50,310			57,913			30,702			24,055			40	%	193	%
Loans and leases past due 90+ days and accruing (1):
	Commercial real estate, net	71			184			1			1			1			(61)	%	nm
	Commercial, net	8,606			7,720			151			7,909			5,143			11	%	67	%
	Residential, net (1)	25,180			21,370			17,423			19,894			21,411			18	%	18	%
	Consumer & other, net	240			399			140			134			152			(40)	%	58	%
	Total loans and leases past due 90+ days and accruing (1)	34,097			29,673			17,715			27,938			26,707			15	%	28	%
Total non-performing loans and leases		104,491			79,983			75,628			58,640			50,762			31	%	106	%
Other real estate owned		1,170			278			409			203			—			321	%	nm
Total non-performing assets		$	105,661		$	80,261		$	76,037		$	58,843		$	50,762		32	%	108	%
Loans and leases past due 31-89 days		$	82,918		$	73,376		$	78,641		$	64,893		$	53,538		13	%	55	%
Loans and leases past due 31-89 days to total loans and leases		0.22		%	0.20		%	0.21		%	0.25		%	0.21		%	0.02		0.01
Non-performing loans and leases to total loans and leases (1)		0.28		%	0.22		%	0.20		%	0.22		%	0.20		%	0.06		0.08
Non-performing assets to total assets (1)		0.20		%	0.15		%	0.14		%	0.18		%	0.16		%	0.05		0.04
nm = not meaningful

(1) Excludes certain mortgage loans guaranteed by Ginnie Mae, which Columbia has the unilateral right to repurchase but has not done so, totaling $700,000, $1.6 million, $5.4 million, $6.6 million and $1.0 million at September 30, 2023, June 30, 2023, March 31, 2023, December 31, 2022 and September 30, 2022, respectively.

Columbia Banking System, Inc. Reports Third Quarter 2023 Results

October 18, 2023

Page 14

	Columbia Banking System, Inc.
	Credit Quality – Allowance for Credit Losses
	(Unaudited)
		Quarter Ended															% Change
($ in thousands)		Sep 30, 2023			Jun 30, 2023			Mar 31, 2023			Dec 31, 2022			Sep 30, 2022			Seq. Quarter		Year over Year
Allowance for credit losses on loans and leases (ACLLL)
Balance, beginning of period		$	404,603		$	417,464		$	301,135		$	283,065		$	261,111		(3)	%	55	%
Initial ACL recorded for PCD loans acquired during the period		—			—			26,492			—			—			nm		nm
Provision for credit losses on loans and leases (1)		35,082			15,216			106,498			30,580			28,542			131	%	23	%
Charge-offs
	Commercial real estate, net	—			(174)			—			(128)			—			nm		nm
	Commercial, net	(26,629)			(32,036)			(19,248)			(14,721)			(9,459)			(17)	%	182	%
	Residential, net	(206)			(4)			(248)			(53)			(4)			nm		nm
	Consumer & other, net	(1,884)			(1,264)			(773)			(906)			(929)			49	%	103	%
	Total charge-offs	(28,719)			(33,478)			(20,269)			(15,808)			(10,392)			(14)	%	176	%
Recoveries
	Commercial real estate, net	31			209			58			163			123			(85)	%	(75)	%
	Commercial, net	4,901			4,511			3,058			2,708			2,842			9	%	72	%
	Residential, net	156			63			123			24			249			148	%	(37)	%
	Consumer & other, net	506			618			369			403			590			(18)	%	(14)	%
	Total recoveries	5,594			5,401			3,608			3,298			3,804			4	%	47	%
Net (charge-offs) recoveries
	Commercial real estate, net	31			35			58			35			123			(11)	%	(75)	%
	Commercial, net	(21,728)			(27,525)			(16,190)			(12,013)			(6,617)			(21)	%	228	%
	Residential, net	(50)			59			(125)			(29)			245			(185)	%	(120)	%
	Consumer & other, net	(1,378)			(646)			(404)			(503)			(339)			113	%	306	%
	Total net charge-offs	(23,125)			(28,077)			(16,661)			(12,510)			(6,588)			(18)	%	251	%
Balance, end of period		$	416,560		$	404,603		$	417,464		$	301,135		$	283,065		3	%	47	%
Reserve for unfunded commitments
Balance, beginning of period		$	19,827		$	19,029		$	14,221		$	11,853		$	12,823		4	%	55	%
Initial ACL recorded for unfunded commitments acquired during the period		—			—			5,767			—			—			nm		nm
Provision (recapture) for credit losses on unfunded commitments		1,655			798			(959)			2,368			(970)			107	%	nm
Balance, end of period		21,482			19,827			19,029			14,221			11,853			8	%	81	%
Total Allowance for credit losses (ACL)		$	438,042		$	424,430		$	436,493		$	315,356		$	294,918		3	%	49	%
Net charge-offs to average loans and leases (annualized)		0.25		%	0.30		%	0.23		%	0.19		%	0.11		%	(0.05)		0.14
Recoveries to gross charge-offs		19.48		%	16.13		%	17.80		%	20.86		%	36.61		%	3.35		(17.13)
ACLLL to loans and leases		1.12		%	1.09		%	1.13		%	1.15		%	1.11		%	0.03		0.01
ACL to loans and leases		1.18		%	1.15		%	1.18		%	1.21		%	1.16		%	0.03		0.02
nm = not meaningful

(1) For the quarter ended March 31, 2023, the provision for credit losses on loans and leases includes $88.4 million initial provision related to non-PCD loans acquired during the period.

Columbia Banking System, Inc. Reports Third Quarter 2023 Results

October 18, 2023

Page 15

Columbia Banking System, Inc.
Credit Quality – Allowance for Credit Losses
(Unaudited)
		Nine Months Ended						% Change
($ in thousands)		Sep 30, 2023			Sep 30, 2022			Year over Year
Allowance for credit losses on loans and leases (ACLLL)
Balance, beginning of period		$	301,135		$	248,412		21	%
Initial ACL recorded for PCD loans acquired during the period		26,492			—			nm
Provision for credit losses on loans and leases (1)		156,796			53,025			196	%
Charge-offs
	Commercial real estate, net	(174)			(8)			nm
	Commercial, net	(77,913)			(26,352)			196	%
	Residential, net	(458)			(171)			168	%
	Consumer & other, net	(3,921)			(2,650)			48	%
	Total charge-offs	(82,466)			(29,181)			183	%
Recoveries
	Commercial real estate, net	298			221			35	%
	Commercial, net	12,470			8,321			50	%
	Residential, net	342			638			(46)	%
	Consumer & other, net	1,493			1,629			(8)	%
	Total recoveries	14,603			10,809			35	%
Net (charge-offs) recoveries
	Commercial real estate, net	124			213			(42)	%
	Commercial, net	(65,443)			(18,031)			263	%
	Residential, net	(116)			467			(125)	%
	Consumer & other, net	(2,428)			(1,021)			138	%
	Total net charge-offs	(67,863)			(18,372)			269	%
Balance, end of period		$	416,560		$	283,065		47	%
Reserve for unfunded commitments
Balance, beginning of period		$	14,221		$	12,767		11	%
Initial ACL recorded for unfunded commitments acquired during the period		5,767			—			nm
Provision (recapture) for credit losses on unfunded commitments		1,494			(914)			nm
Balance, end of period		21,482			11,853			81	%
Total Allowance for credit losses (ACL)		$	438,042		$	294,918		49	%
Net charge-offs to average loans and leases (annualized)		0.26		%	0.10		%	0.16
Recoveries to gross charge-offs		17.71		%	37.04		%	(19.33)
nm = not meaningful

(1) For the nine months ended September 30, 2023, the provision for credit losses on loans and leases includes $88.4 million initial provision related to non-PCD loans acquired during the period.

Columbia Banking System, Inc. Reports Third Quarter 2023 Results

October 18, 2023

Page 16

Columbia Banking System, Inc.
Consolidated Average Balance Sheets, Net Interest Income, and Yields/Rates
(Unaudited)
	Quarter Ended
	September 30, 2023						June 30, 2023						September 30, 2022
($ in thousands)	Average Balance		Interest Income or Expense		Average Yields or Rates		Average Balance		Interest Income or Expense		Average Yields or Rates		Average Balance		Interest Income or Expense		Average Yields or Rates
INTEREST-EARNING ASSETS:
Loans held for sale	$	199,855	$	1,741	3.49	%	$	46,794	$	682	5.83	%	$	173,397	$	2,205	5.09	%
Loans and leases (1)	37,050,518		567,929		6.08	%	37,169,315		551,997		5.95	%	24,886,203		276,625		4.41	%
Taxable securities	8,356,165		85,007		4.07	%	8,656,147		81,617		3.77	%	3,271,185		18,261		2.23	%
Non-taxable securities (2)	844,417		8,085		3.83	%	865,278		8,010		3.70	%	212,847		1,651		3.10	%
Temporary investments and interest-bearing cash	2,530,150		34,407		5.40	%	2,704,984		34,616		5.13	%	893,471		5,115		2.27	%
Total interest-earning assets	48,981,105		$	697,169	5.65	%	49,442,518		$	676,922	5.48	%	29,437,103		$	303,857	4.10	%
Goodwill and other intangible assets	1,684,093						1,718,705						6,343
Other assets	2,346,163						2,379,351						1,224,731
Total assets	$	53,011,361					$	53,540,574					$	30,668,177
INTEREST-BEARING LIABILITIES:
Interest-bearing demand deposits	$	6,578,849	$	25,209	1.52	%	$	6,131,117	$	17,277	1.15	%	$	3,829,688	$	1,705	0.18	%
Money market deposits	10,249,028		50,039		1.94	%	10,362,495		41,703		1.60	%	7,550,791		5,817		0.31	%
Savings deposits	3,109,779		1,253		0.16	%	3,297,138		877		0.11	%	2,468,187		250		0.04	%
Time deposits	5,184,089		50,473		3.86	%	4,703,967		40,551		3.46	%	1,501,724		1,318		0.35	%
Total interest-bearing deposits	25,121,745		126,974		2.01	%	24,494,717		100,408		1.64	%	15,350,390		9,090		0.23	%
Repurchase agreements and federal funds purchased	268,444		1,220		1.80	%	284,347		1,071		1.51	%	509,559		545		0.42	%
Borrowings	5,603,207		77,080		5.46	%	6,187,363		81,004		5.25	%	90,475		798		3.50	%
Junior and other subordinated debentures	420,582		9,864		9.30	%	405,989		9,271		9.16	%	409,151		5,491		5.33	%
Total interest-bearing liabilities	31,413,978		$	215,138	2.72	%	31,372,416		$	191,754	2.45	%	16,359,575		$	15,924	0.39	%
Non-interest-bearing deposits	15,759,720						16,361,541						11,250,764
Other liabilities	970,688						871,378						490,572
Total liabilities	48,144,386						48,605,335						28,100,911
Common equity	4,866,975						4,935,239						2,567,266
Total liabilities and shareholders' equity	$	53,011,361					$	53,540,574					$	30,668,177
NET INTEREST INCOME (2)			$	482,031					$	485,168					$	287,933
NET INTEREST SPREAD					2.93	%					3.03	%					3.71	%
NET INTEREST INCOME TO EARNING ASSETS OR NET INTEREST MARGIN (1), (2)					3.91	%					3.93	%					3.88	%

(1)Non-accrual loans and leases are included in the average balance.   

(2)Tax-exempt income has been adjusted to a tax equivalent basis at a 21% tax rate. The amount of such adjustment was an addition to recorded income of approximately $1.2 million for the three months ended September 30, 2023, as compared to $1.2 million for the three months ended June 30, 2023 and $329,000 for the three months ended September 30, 2022. 

Columbia Banking System, Inc. Reports Third Quarter 2023 Results

October 18, 2023

Page 17

Columbia Banking System, Inc.
Consolidated Average Balance Sheets, Net Interest Income, and Yields/Rates
(Unaudited)
	Nine Months Ended
	September 30, 2023						September 30, 2022
($ in thousands)	Average Balance		Interest Income or Expense		Average Yields or Rates		Average Balance		Interest Income or Expense		Average Yields or Rates
INTEREST-EARNING ASSETS:
Loans held for sale	$	100,753	$	3,222	4.26	%	$	240,928	$	7,209	3.99	%
Loans and leases (1)	34,765,319		1,532,652		5.88	%	23,676,201		720,699		4.06	%
Taxable securities	7,336,862		207,072		3.76	%	3,445,386		54,412		2.11	%
Non-taxable securities (2)	717,064		20,163		3.75	%	222,375		5,098		3.06	%
Temporary investments and interest-bearing cash	2,283,461		87,604		5.13	%	1,718,832		9,387		0.73	%
Total interest-earning assets	45,203,459		$	1,850,713	5.46	%	29,303,722		$	796,805	3.62	%
Goodwill and other intangible assets	1,345,833						7,369
Other assets	2,159,775						1,229,936
Total assets	$	48,709,067					$	30,541,027
INTEREST-BEARING LIABILITIES:
Interest-bearing demand deposits	$	5,829,737	$	52,301	1.20	%	$	3,846,202	$	2,813	0.10	%
Money market deposits	9,857,001		123,980		1.68	%	7,519,200		8,942		0.16	%
Savings deposits	3,032,653		2,686		0.12	%	2,433,651		654		0.04	%
Time deposits	4,371,643		112,028		3.43	%	1,623,742		4,612		0.38	%
Total interest-bearing deposits	23,091,034		290,995		1.68	%	15,422,795		17,021		0.15	%
Repurchase agreements and federal funds purchased	277,896		2,697		1.30	%	502,998		674		0.18	%
Borrowings	4,726,335		186,848		5.29	%	34,662		897		3.46	%
Junior and other subordinated debentures	414,855		27,605		8.90	%	394,803		12,641		4.28	%
Total interest-bearing liabilities	28,510,120		$	508,145	2.38	%	16,355,258		$	31,233	0.26	%
Non-interest-bearing deposits	14,937,028						11,115,618
Other liabilities	872,370						448,426
Total liabilities	44,319,518						27,919,302
Common equity	4,389,549						2,621,725
Total liabilities and shareholders' equity	$	48,709,067					$	30,541,027
NET INTEREST INCOME (2)			$	1,342,568					$	765,572
NET INTEREST SPREAD					3.08	%					3.36	%
NET INTEREST INCOME TO EARNING ASSETS OR NET INTEREST MARGIN (1), (2)					3.96	%					3.48	%

(1)Non-accrual loans and leases are included in the average balance.   

(2)Tax-exempt income has been adjusted to a tax equivalent basis at a 21% tax rate. The amount of such adjustment was an addition to recorded income of approximately $3.0 million for the nine months ended September 30, 2023, as compared to $1.0 million for the same period in 2022. 

Columbia Banking System, Inc. Reports Third Quarter 2023 Results

October 18, 2023

Page 18

Columbia Banking System, Inc.
Residential Mortgage Banking Activity
(Unaudited)
	Quarter Ended															% Change
($ in thousands)	Sep 30, 2023			Jun 30, 2023			Mar 31, 2023			Dec 31, 2022			Sep 30, 2022			Seq. Quarter		Year over Year
Residential mortgage banking revenue:
Origination and sale	$	2,442		$	3,166		$	3,587		$	4,252		$	10,515		(23)	%	(77)	%
Servicing	8,887			9,167			9,397			9,184			9,529			(3)	%	(7)	%
Change in fair value of MSR asset:
Changes due to collection/realization of expected cash flows over time	(4,801)			(4,797)			(4,881)			(4,986)			(4,978)			0	%	(4)	%
Changes due to valuation inputs or assumptions	5,308			(2,242)			(2,937)			(9,914)			16,403			nm		(68)	%
MSR hedge (loss) gain	(4,733)			(7,636)			2,650			(348)			(14,128)			(38)	%	(66)	%
Total	$	7,103		$	(2,342)		$	7,816		$	(1,812)		$	17,341		nm		(59)	%
Closed loan volume for-sale	$	103,333		$	119,476		$	131,726		$	216,833		$	396,979		(14)	%	(74)	%
Gain on sale margin	2.36		%	2.65		%	2.72		%	1.96		%	2.65		%	(0.29)		(0.29)
Residential mortgage servicing rights:
Balance, beginning of period	$	172,929		$	178,800		$	185,017		$	196,177		$	179,558		(3)	%	(4)	%
Additions for new MSR capitalized	1,658			1,168			1,601			3,740			5,194			42	%	(68)	%
Sale of MSR assets	(57,454)			—			—			—			—			nm		nm
Change in fair value of MSR asset:
Changes due to collection/realization of expected cash flows over time	(4,801)			(4,797)			(4,881)			(4,986)			(4,978)			0	%	(4)	%
Changes due to valuation inputs or assumptions	5,308			(2,242)			(2,937)			(9,914)			16,403			nm		(68)	%
Balance, end of period	$	117,640		$	172,929		$	178,800		$	185,017		$	196,177		(32)	%	(40)	%
Residential mortgage loans serviced for others	$	8,240,950		$	12,726,615		$	12,914,046		$	13,020,189		$	12,997,911		(35)	%	(37)	%
MSR as % of serviced portfolio	1.43		%	1.36		%	1.38		%	1.42		%	1.51		%	0.07		(0.08)
nm = not meaningful

Columbia Banking System, Inc. Reports Third Quarter 2023 Results

October 18, 2023

Page 19

Columbia Banking System, Inc.
Residential Mortgage Banking Activity
(Unaudited)
	Nine Months Ended						% Change
($ in thousands)	Sep 30, 2023			Sep 30, 2022			Year over Year
Residential mortgage banking revenue:
Origination and sale	$	9,195		$	42,460		(78)	%
Servicing	27,451			28,174			(3)	%
Change in fair value of MSR asset:
Changes due to collection/realization of expected cash flows over time	(14,479)			(15,286)			(5)	%
Changes due to valuation inputs or assumptions	129			67,451			(100)	%
MSR hedge loss	(9,719)			(14,128)			(31)	%
Total	$	12,577		$	108,671		(88)	%
Closed loan volume for-sale	$	354,535		$	1,622,633		(78)	%
Gain on sale margin	2.59		%	2.62		%	(0.03)
Residential mortgage servicing rights:
Balance, beginning of period	$	185,017		$	123,615		50	%
Additions for new MSR capitalized	4,427			20,397			(78)	%
Sale of MSR assets	(57,454)			—			nm
Change in fair value of MSR asset:
Changes due to collection/realization of expected cash flows over time	(14,479)			(15,286)			(5)	%
Changes due to valuation inputs or assumptions	129			67,451			(100)	%
Balance, end of period	$	117,640		$	196,177		(40)	%
nm = not meaningful

Columbia Banking System, Inc. Reports Third Quarter 2023 Results

October 18, 2023

Page 20

Non-GAAP Financial Measures

In addition to results presented in accordance with generally accepted accounting principles in the United States of America ("GAAP"), this press release contains certain non-GAAP financial measures. The company believes presenting certain non-GAAP financial measures provides investors with information useful in understanding our financial performance, our performance trends, and our financial position. We utilize these measures for internal planning and forecasting purposes. We, as well as securities analysts, investors, and other interested parties, also use these measures to compare peer company operating performance. We believe that our presentation and discussion, together with the accompanying reconciliations, provides a complete understanding of factors and trends affecting our business and allows investors to view performance in a manner similar to management. These non-GAAP measures should not be considered a substitution for GAAP basis measures and results, and we strongly encourage investors to review our consolidated financial statements in their entirety and not to rely on any single financial measure. Because non-GAAP financial measures are not standardized, it may not be possible to compare these financial measures with other companies’ non-GAAP financial measures having the same or similar names.

Columbia Banking System, Inc.
GAAP to Non-GAAP Reconciliation
(Unaudited)
		Quarter Ended															% Change
($ in thousands, except per share data)		Sep 30, 2023			Jun 30, 2023			Mar 31, 2023			Dec 31, 2022			Sep 30, 2022			Seq. Quarter		Year over Year
Total shareholders' equity	a	$	4,632,162		$	4,828,188		$	4,884,723		$	2,479,826		$	2,417,514		(4)	%	92	%
Less: Goodwill		1,029,234			1,029,234			1,030,142			—			—			—	%	nm
Less: Other intangible assets, net		636,883			666,762			702,315			4,745			5,764			(4)	%	nm
Tangible common shareholders' equity	b	$	2,966,045		$	3,132,192		$	3,152,266		$	2,475,081		$	2,411,750		(5)	%	23	%
Total assets	c	$	51,989,593		$	53,592,096		$	53,994,226		$	31,848,639		$	31,471,960		(3)	%	65	%
Less: Goodwill		1,029,234			1,029,234			1,030,142			—			—			0	%	nm
Less: Other intangible assets, net		636,883			666,762			702,315			4,745			5,764			(4)	%	nm
Tangible assets	d	$	50,323,476		$	51,896,100		$	52,261,769		$	31,843,894		$	31,466,196		(3)	%	60	%
Common shares outstanding at period end (1)	e	208,575			208,514			208,429			129,321			129,320			0	%	61	%
Total shareholders' equity to total assets ratio	a / c	8.91		%	9.01		%	9.05		%	7.79		%	7.68		%	(0.10)		1.23
Tangible common equity ratio	b / d	5.89		%	6.04		%	6.03		%	7.77		%	7.66		%	(0.15)		(1.77)
Book value per common share (1)	a / e	$	22.21		$	23.16		$	23.44		$	19.18		$	18.69		(4)	%	19	%
Tangible book value per common share (1)	b / e	$	14.22		$	15.02		$	15.12		$	19.14		$	18.65		(5)	%	(24)	%
nm = not meaningful

(1) Periods prior to February 28, 2023, have been restated as a result of the adjustment to common shares outstanding based on the exchange ratio from the UHC merger of 0.5958.

Columbia Banking System, Inc. Reports Third Quarter 2023 Results

October 18, 2023

Page 21

Columbia Banking System, Inc.
GAAP to Non-GAAP Reconciliation - Continued
(Unaudited)
		Quarter Ended										% Change
($ in thousands)		Sep 30, 2023		Jun 30, 2023		Mar 31, 2023		Dec 31, 2022		Sep 30, 2022		Seq. Quarter		Year over Year
Non-Interest Income Adjustments
Gain on sale of debt securities, net		$	4	$	—	$	—	$	—	$	—	nm		nm
(Loss) gain on equity securities, net		(2,055)		(697)		2,416		284		(2,647)		195	%	(22)	%
Gain (loss) on swap derivatives		5,700		1,288		(3,543)		(2,329)		4,194		343	%	36	%
Change in fair value of certain loans held for investment		(19,247)		(6,965)		9,488		4,192		(26,397)		176	%	(27)	%
Change in fair value of MSR due to valuation inputs or assumptions		5,308		(2,242)		(2,937)		(9,914)		16,403		nm		(68)	%
MSR hedge (loss) gain		(4,733)		(7,636)		2,650		(348)		(14,128)		(38)	%	(66)	%
Total non-interest income adjustments	a	$	(15,023)	$	(16,252)	$	8,074	$	(8,115)	$	(22,575)	(8)	%	(33)	%
Non-Interest Expense Adjustments
Merger related expense		$	18,938	$	29,649	$	115,898	$	11,637	$	769	(36)	%	nm
Exit and disposal costs		4,017		2,119		1,291		1,966		1,364		90	%	195	%
Total non-interest expense adjustments	b	$	22,955	$	31,768	$	117,189	$	13,603	$	2,133	(28)	%	nm
Net interest income	c	$	480,875	$	483,975	$	374,698	$	305,479	$	287,604	(1)	%	67	%
Non-interest income (GAAP)	d	$	43,981	$	39,678	$	54,735	$	34,879	$	29,445	11	%	49	%
Less: Non-interest income adjustments	a	15,023		16,252		(8,074)		8,115		22,575		(8)	%	(33)	%
Operating non-interest income (non-GAAP)	e	$	59,004	$	55,930	$	46,661	$	42,994	$	52,020	5	%	13	%
Revenue (GAAP)	f=c+d	$	524,856	$	523,653	$	429,433	$	340,358	$	317,049	—	%	66	%
Operating revenue (non-GAAP)	g=c+e	$	539,879	$	539,905	$	421,359	$	348,473	$	339,624	—	%	59	%
Non-interest expense (GAAP)	h	$	304,147	$	328,559	$	342,818	$	194,982	$	177,964	(7)	%	71	%
Less: Non-interest expense adjustments	b	(22,955)		(31,768)		(117,189)		(13,603)		(2,133)		(28)	%	nm
Operating non-interest expense (non-GAAP)	i	$	281,192	$	296,791	$	225,629	$	181,379	$	175,831	(5)	%	60	%
Net income (loss) (GAAP)	j	$	135,845	$	133,377	$	(14,038)	$	82,964	$	84,040	2	%	62	%
Provision (benefit) for income taxes		48,127		45,703		(4,886)		29,464		27,473		5	%	75	%
Income (loss) before provision for income taxes		183,972		179,080		(18,924)		112,428		111,513		3	%	65	%
Provision for credit losses		36,737		16,014		105,539		32,948		27,572		129	%	33	%
Pre-provision net revenue (PPNR) (non-GAAP)	k	220,709		195,094		86,615		145,376		139,085		13	%	59	%
Less: Non-interest income adjustments	a	15,023		16,252		(8,074)		8,115		22,575		(8)	%	(33)	%
Add: Non-interest expense adjustments	b	22,955		31,768		117,189		13,603		2,133		(28)	%	nm
Operating PPNR (non-GAAP)	l	$	258,687	$	243,114	$	195,730	$	167,094	$	163,793	6	%	58	%
Net income (loss) (GAAP)	j	$	135,845	$	133,377	$	(14,038)	$	82,964	$	84,040	2	%	62	%
Less: Non-interest income adjustments	a	15,023		16,252		(8,074)		8,115		22,575		(8)	%	(33)	%
Add: Non-interest expense adjustments	b	22,955		31,768		117,189		13,603		2,133		(28)	%	nm
Tax effect of adjustments		(9,482)		(11,981)		(23,565)		(5,459)		(6,116)		(21)	%	55	%
Operating net income (non-GAAP)	m	$	164,341	$	169,416	$	71,512	$	99,223	$	102,632	(3)	%	60	%
nm = not meaningful

Columbia Banking System, Inc. Reports Third Quarter 2023 Results

October 18, 2023

Page 22

Columbia Banking System, Inc.
GAAP to Non-GAAP Reconciliation - Continued
(Unaudited)
		Quarter Ended															% Change
($ in thousands, except per share data)		Sep 30, 2023			Jun 30, 2023			Mar 31, 2023			Dec 31, 2022			Sep 30, 2022			Seq. Quarter		Year over Year
Average assets	n	$	53,011,361		$	53,540,574		$	39,425,975		$	31,637,490		$	30,668,177		(1)	%	73	%
Less: Average goodwill and other intangible assets, net		1,684,093			1,718,705			623,042			5,298			6,343			(2)	%	nm
Average tangible assets	o	$	51,327,268		$	51,821,869		$	38,802,933		$	31,632,192		$	30,661,834		(1)	%	67	%
Average common shareholders' equity	p	$	4,866,975		$	4,935,239		$	3,349,761		$	2,438,639		$	2,567,266		(1)	%	90	%
Less: Average goodwill and other intangible assets, net		1,684,093			1,718,705			623,042			5,298			6,343			(2)	%	nm
Average tangible common equity	q	$	3,182,882		$	3,216,534		$	2,726,719		$	2,433,341		$	2,560,923		(1)	%	24	%
Weighted average basic shares outstanding (1)	r	208,070			207,977			156,383			129,321			129,319			0	%	61	%
Weighted average diluted shares outstanding (1)	s	208,645			208,545			156,383			129,801			129,733			0	%	61	%
Select Per-Share & Performance Metrics
Earnings-per-share - basic (1)	j / r	$	0.65		$	0.64		$	(0.09)		$	0.64		$	0.65		2	%	—	%
Earnings-per-share - diluted (1)	j / s	$	0.65		$	0.64		$	(0.09)		$	0.64		$	0.65		2	%	—	%
Efficiency ratio (2)	h / f	57.82		%	62.60		%	79.71		%	57.24		%	56.07		%	(4.78)		1.75
Return on average assets	j / n	1.02		%	1.00		%	(0.14)		%	1.04		%	1.09		%	0.02		(0.07)
Return on average tangible assets	j / o	1.05		%	1.03		%	(0.15)		%	1.04		%	1.09		%	0.02		(0.04)
PPNR return on average assets	k / n	1.65		%	1.46		%	0.89		%	1.82		%	1.80		%	0.19		(0.15)
Return on average common equity	j / p	11.07		%	10.84		%	(1.70)		%	13.50		%	12.99		%	0.23		(1.92)
Return on average tangible common equity	j / q	16.93		%	16.63		%	(2.09)		%	13.53		%	13.02		%	0.30		3.91
Operating Per-Share & Performance Metrics
Operating earnings-per-share - basic (1)	m / r	$	0.79		$	0.81		$	0.46		$	0.77		$	0.79		(2)	%	—	%
Operating earnings-per-share - diluted (1)	m / s	$	0.79		$	0.81		$	0.46		$	0.76		$	0.79		(2)	%	—	%
Operating efficiency ratio (2)	i / g	51.97		%	54.85		%	53.46		%	52.01		%	51.72		%	(2.88)		0.25
Operating return on average assets	m / n	1.23		%	1.27		%	0.74		%	1.24		%	1.33		%	(0.04)		(0.10)
Operating return on average tangible assets	m / o	1.27		%	1.31		%	0.75		%	1.24		%	1.33		%	(0.04)		(0.06)
Operating PPNR return on average assets	l / n	1.94		%	1.82		%	2.01		%	2.10		%	2.12		%	0.12		(0.18)
Operating return on average common equity	m / p	13.40		%	13.77		%	8.66		%	16.14		%	15.86		%	(0.37)		(2.46)
Operating return on average tangible common equity	m / q	20.48		%	21.13		%	10.64		%	16.18		%	15.90		%	(0.65)		4.58

(1) Periods prior to February 28, 2023, have been restated as a result of the adjustment to common shares outstanding based on the exchange ratio from the UHC merger of 0.5958.

(2) Tax exempt interest has been adjusted to a taxable equivalent basis using a 21% tax rate and added to stated revenue for this calculation.

Columbia Banking System, Inc. Reports Third Quarter 2023 Results

October 18, 2023

Page 23

Columbia Banking System, Inc.
GAAP to Non-GAAP Reconciliation - Continued
(Unaudited)
		Nine Months Ended				% Change
($ in thousands)		Sep 30, 2023		Sep 30, 2022		Year over Year
Non-Interest Income Adjustments
Gain on sale of debt securities, net		$	4	$	2	100	%
Loss on equity securities, net		(336)		(7,383)		(95)	%
Gain on swap derivatives		3,445		18,578		(81)	%
Change in fair value of certain loans held for investment		(16,724)		(62,656)		(73)	%
Change in fair value of MSR due to valuation inputs or assumptions		129		67,451		(100)	%
MSR hedge loss		(9,719)		(14,128)		(31)	%
Total non-interest income adjustments	a	$	(23,201)	$	1,864	nm
Non-Interest Expense Adjustments
Merger related expense		$	164,485	$	5,719	nm
Exit and disposal costs		7,427		4,839		53	%
Total non-interest expense adjustments	b	$	171,912	$	10,558	nm
Net interest income	c	$	1,339,548	$	764,537	75	%
Non-interest income (GAAP)	d	$	138,394	$	164,649	(16)	%
Less: Non-interest income adjustments	a	23,201		(1,864)		nm
Operating non-interest income (non-GAAP)	e	$	161,595	$	162,785	(1)	%
Revenue (GAAP)	f=c+d	$	1,477,942	$	929,186	59	%
Operating revenue (non-GAAP)	g=c+e	$	1,501,143	$	927,322	62	%
Non-interest expense (GAAP)	h	$	975,524	$	539,968	81	%
Less: Non-interest expense adjustments	b	(171,912)		(10,558)		nm
Operating non-interest expense (non-GAAP)	i	$	803,612	$	529,410	52	%
Net income (GAAP)	j	$	255,184	$	253,788	1	%
Provision for income taxes		88,944		84,362		5	%
Income before provision for income taxes		344,128		338,150		2	%
Provision for credit losses		158,290		51,068		210	%
Pre-provision net revenue (PPNR) (non-GAAP)	k	502,418		389,218		29	%
Less: Non-interest income adjustments	a	23,201		(1,864)		nm
Add: Non-interest expense adjustments	b	171,912		10,558		nm
Operating PPNR (non-GAAP)	l	$	697,531	$	397,912	75	%
Net income (GAAP)	j	$	255,184	$	253,788	1	%
Less: Non-interest income adjustments	a	23,201		(1,864)		nm
Add: Non-interest expense adjustments	b	171,912		10,558		nm
Tax effect of adjustments		(45,028)		(2,020)		nm
Operating net income (non-GAAP)	m	$	405,269	$	260,462	56	%
nm = not meaningful

Columbia Banking System, Inc. Reports Third Quarter 2023 Results

October 18, 2023

Page 24

Columbia Banking System, Inc.
GAAP to Non-GAAP Reconciliation - Continued
(Unaudited)
		Nine Months Ended						% Change
($ in thousands)		Sep 30, 2023			Sep 30, 2022			Year over Year
Average assets	n	$	48,709,067		$	30,541,027		59	%
Less: Average goodwill and other intangible assets, net		1,345,833			7,369			nm
Average tangible assets	o	$	47,363,234		$	30,533,658		55	%
Average common shareholders' equity	p	$	4,389,549		$	2,621,725		67	%
Less: Average goodwill and other intangible assets, net		1,345,833			7,369			nm
Average tangible common equity	q	$	3,043,716		$	2,614,356		16	%
Weighted average basic shares outstanding (1)	r	190,997			129,262			48	%
Weighted average diluted shares outstanding (1)	s	191,546			129,702			48	%
Select Per-Share & Performance Metrics
Earnings-per-share - basic (1)	j / r	$	1.34		$	1.96		(32)	%
Earnings-per-share - diluted (1)	j / s	$	1.33		$	1.96		(32)	%
Efficiency ratio (2)	h / f	65.87		%	58.05		%	7.82
Return on average assets	j / n	0.70		%	1.11		%	(0.41)
Return on average tangible assets	j / o	0.72		%	1.11		%	(0.39)
PPNR return on average assets	k/n	1.38		%	1.70		%	(0.32)
Return on average common equity	j / p	7.77		%	12.94		%	(5.17)
Return on average tangible common equity	j / q	11.21		%	12.98		%	(1.77)
Operating Per-Share & Performance Metrics
Operating earnings-per-share - basic (1)	m / r	$	2.12		$	2.01		5	%
Operating earnings-per-share - diluted (1)	m / s	$	2.12		$	2.01		5	%
Operating efficiency ratio (2)	i / g	53.43		%	57.03		%	(3.60)
Operating return on average assets	m / n	1.11		%	1.14		%	(0.03)
Operating return on average tangible assets	m / o	1.14		%	1.14		%	—
Operating PPNR return on average assets	l / n	1.91		%	1.74		%	0.17
Operating return on average common equity	m / p	12.34		%	13.28		%	(0.94)
Operating return on average tangible common equity	m / q	17.80		%	13.32		%	4.48

(1) Periods prior to February 28, 2023, have been restated as a result of the adjustment to common shares outstanding based on the exchange ratio from the UHC merger of 0.5958.

(2) Tax exempt interest has been adjusted to a taxable equivalent basis using a 21% tax rate and added to stated revenue for this calculation.

Columbia Banking System, Inc. Reports Third Quarter 2023 Results

October 18, 2023

Page 25

Columbia Banking System, Inc.
GAAP to Non-GAAP Reconciliation - Continued
(Unaudited)
		Quarter Ended										% Change
($ in thousands)		Sep 30, 2023		Jun 30, 2023		Mar 31, 2023		Dec 31, 2022		Sep 30, 2022		Seq. Quarter		Year over Year
Loans and leases interest income	a	$	567,929	$	551,997	$	412,726	$	320,747	$	276,625	3	%	105	%
Less: Acquired loan accretion - rate related (2), (3)	b	28,963		30,548		11,832		387		789		(5)	%	nm
Less: Acquired loan accretion - credit related (3)	c	6,370		7,100		3,806		—		—		(10)	%	nm
Adjusted loans and leases interest income	d=a-b-c	$	532,596	$	514,349	$	397,088	$	320,360	$	275,836	4	%	93	%
Taxable securities interest income	e	$	85,007	$	81,617	$	40,448	$	18,290	$	18,261	4	%	366	%
Less: Acquired taxable securities accretion - rate related	f	39,219		34,801		15,356		—		—		13	%	nm
Adjusted Taxable securities interest income	g=e-f	$	45,788	$	46,816	$	25,092	$	18,290	$	18,261	(2)	%	151	%
Non-taxable securities interest income (1)	h	$	8,085	$	8,010	$	4,068	$	1,571	$	1,651	1	%	390	%
Less: Acquired non-taxable securities accretion - rate related	i	2,288		2,274		901		—		—		1	%	nm
Adjusted Taxable securities interest income (1)	j=h-i	$	5,797	$	5,736	$	3,167	$	1,571	$	1,651	1	%	251	%
Interest income (1)	k	$	697,169	$	676,922	$	476,622	$	352,530	$	303,857	3	%	129	%
Less: Acquired loan and securities accretion - rate related	l=b+f+i	70,470		67,623		28,089		387		789		4	%	nm
Less: Acquired loan accretion - credit related	c	6,370		7,100		3,806		—		—		(10)	%	nm
Adjusted interest income (1)	m=k-l-c	$	620,329	$	602,199	$	444,727	$	352,143	$	303,068	3	%	105	%
Interest-bearing deposits interest expense	n	$	126,974	$	100,408	$	63,613	$	31,174	$	9,090	26	%	nm
Less: Acquired deposit accretion	o	(373)		(280)		(93)		—		—		33	%	nm
Adjusted interest-bearing deposits interest expense	p=n-o	$	127,347	$	100,688	$	63,706	$	31,174	$	9,090	26	%	nm
Interest expense	q	$	215,138	$	191,754	$	101,253	$	46,768	$	15,924	12	%	nm
Less: Acquired interest-bearing liabilities accretion (2)	r	(430)		(337)		(150)		(57)		(57)		28	%	nm
Adjusted interest expense	s=q-r	$	215,568	$	192,091	$	101,403	$	46,825	$	15,981	12	%	nm
Net Interest Income (1)	t	$	482,031	$	485,168	$	375,369	$	305,762	$	287,933	(1)	%	67	%
Less: Acquired loan, securities, and interest-bearing liabilities accretion - rate related (3)	u=l-r	70,900		67,960		28,239		444		846		4	%	nm
Less: Acquired loan accretion - credit related (3)	c	6,370		7,100		3,806		—		—		(10)	%	nm
Adjusted net interest income (1)	v=t-u-c	$	404,761	$	410,108	$	343,324	$	305,318	$	287,087	(1)	%	41	%
Average loans and leases	aa	37,050,518		37,169,315		29,998,630		25,855,556		24,886,203		0	%	49	%
Average taxable securities	ab	8,356,165		8,656,147		4,960,966		3,042,044		3,271,185		(3)	%	155	%
Average non-taxable securities	ac	844,417		865,278		437,020		200,825		212,847		(2)	%	297	%
Average interest-earning assets	ad	48,981,105		49,442,518		37,055,705		30,305,129		29,437,103		(1)	%	66	%
Average interest-bearing deposits	ae	25,121,745		24,494,717		19,496,551		16,103,984		15,350,390		3	%	64	%
Average interest-bearing liabilities	af	31,413,978		31,372,416		22,548,264		17,668,730		16,359,575		0	%	92	%

(1)Tax exempt interest has been adjusted to a taxable equivalent basis using a 21% tax rate.

(2)Includes discount accretion related to UHC's 2014 acquisition of Sterling Financial Corporation.

(3)The cumulative fair value discount on historical Columbia loans was established as of February 28, 2023, and the allocation between the credit-related discount and the rate-related discount was established at that time. Our disclosure of credit-related and rate-related discount accretion is an estimate based on the relative allocation of these two items to the discount at closing. 

Columbia Banking System, Inc. Reports Third Quarter 2023 Results

October 18, 2023

Page 26

Columbia Banking System, Inc.
GAAP to Non-GAAP Reconciliation - Continued
(Unaudited)
		Quarter Ended										% Change
($ in thousands)		Sep 30, 2023		Jun 30, 2023		Mar 31, 2023		Dec 31, 2022		Sep 30, 2022		Seq. Quarter	Year over Year
Average yield on loans and leases	a / aa	6.08	%	5.95	%	5.55	%	4.92	%	4.41	%	0.13	1.67
Less: Acquired loan accretion - rate related (2),(3)	b / aa	0.31	%	0.33	%	0.16	%	0.01	%	0.01	%	(0.02)	0.30
Less: Acquired loan accretion - credit related (3)	c / aa	0.07	%	0.08	%	0.05	%	—	%	—	%	(0.01)	0.07
Adjusted average yield on loans and leases	d / aa	5.70	%	5.54	%	5.34	%	4.91	%	4.40	%	0.16	1.30
Average yield on taxable securities	e / ab	4.07	%	3.77	%	3.26	%	2.40	%	2.23	%	0.30	1.84
Less: Acquired taxable securities accretion - rate related	f / ab	1.86	%	1.61	%	1.26	%	—	%	—	%	0.25	1.86
Adjusted average yield on taxable securities	g / ab	2.21	%	2.16	%	2.00	%	2.40	%	2.23	%	0.05	(0.02)
Average yield on non-taxable securities (1)	h / ac	3.83	%	3.70	%	3.72	%	3.13	%	3.10	%	0.13	0.73
Less: Acquired non-taxable securities accretion - rate related	i / ac	1.07	%	1.05	%	0.84	%	—	%	—	%	0.02	1.07
Adjusted yield on non-taxable securities (1)	j / ac	2.76	%	2.65	%	2.88	%	3.13	%	3.10	%	0.11	(0.34)
Average yield on interest-earning assets (1)	k / ad	5.65	%	5.48	%	5.19	%	4.62	%	4.10	%	0.17	1.55
Less: Acquired loan and securities accretion - rate related	l / ad	0.57	%	0.55	%	0.31	%	0.01	%	0.01	%	0.02	0.56
Less: Acquired loan accretion - credit related	c / ad	0.05	%	0.06	%	0.04	%	—	%	—	%	(0.01)	0.05
Adjusted average yield on interest-earning assets (1)	m / ad	5.03	%	4.87	%	4.84	%	4.61	%	4.09	%	0.16	0.94
Average rate on interest-bearing deposits	n / ae	2.01	%	1.64	%	1.32	%	0.77	%	0.23	%	0.37	1.78
Less: Acquired deposit accretion	o / ae	(0.01)	%	—	%	—	%	—	%	—	%	(0.01)	(0.01)
Adjusted average rate on interest-bearing deposits	p / ae	2.02	%	1.64	%	1.32	%	0.77	%	0.23	%	0.38	1.79
Average rate on interest-bearing liabilities	q / af	2.72	%	2.45	%	1.82	%	1.05	%	0.39	%	0.27	2.33
Less: Acquired interest-bearing liabilities accretion (2)	r / af	(0.01)	%	—	%	—	%	—	%	—	%	(0.01)	(0.01)
Adjusted average rate on interest-bearing liabilities	s / af	2.73	%	2.45	%	1.82	%	1.05	%	0.39	%	0.28	2.34
Net interest margin (1)	t / ad	3.91	%	3.93	%	4.08	%	4.01	%	3.88	%	(0.02)	0.03
Less: Acquired loan, securities, and interest-bearing liabilities accretion - rate related (3)	u / ad	0.58	%	0.55	%	0.31	%	—	%	0.01	%	0.03	0.57
Less: Acquired loan accretion - credit related (3)	c / ad	0.05	%	0.06	%	0.04	%	—	%	—	%	(0.01)	0.05
Adjusted net interest margin (1)	v / ad	3.28	%	3.32	%	3.73	%	4.01	%	3.87	%	(0.04)	(0.59)

(1)Tax exempt interest has been adjusted to a taxable equivalent basis using a 21% tax rate.

(2) Includes discount accretion related to UHC's 2014 acquisition of Sterling Financial Corporation.

(3)The cumulative fair value discount on historical Columbia loans was established as of February 28, 2023, and the allocation between the credit-related discount and the rate-related discount was established at that time. Our disclosure of credit-related and rate-related discount accretion is an estimate based on the relative allocation of these two items to the discount at closing. 

Columbia Banking System, Inc. Reports Third Quarter 2023 Results

October 18, 2023

Page 27

Columbia Banking System, Inc.
GAAP to Non-GAAP Reconciliation - Continued
(Unaudited)
		Nine Months Ended
($ in thousands)		Sep 30, 2023		Sep 30, 2022		Year over Year
Loans and leases interest income	a	$	1,532,652	$	720,699	113	%
Less: Acquired loan accretion - rate related (2), (3)	b	71,343		3,290		nm
Less: Acquired loan accretion - credit related (3)	c	17,276		—		nm
Adjusted loans and leases interest income	d=a-b-c	$	1,444,033	$	717,409	101	%
Taxable securities interest income	e	$	207,072	$	54,412	281	%
Less: Acquired taxable securities accretion - rate related	f	89,376		—		nm
Adjusted Taxable securities interest income	g=e-f	$	117,696	$	54,412	116	%
Non-taxable securities interest income (1)	h	$	20,163	$	5,098	296	%
Less: Acquired non-taxable securities accretion - rate related	i	5,463		—		nm
Adjusted Taxable securities interest income (1)	j=h-i	$	14,700	$	5,098	188	%
Interest income (1)	k	$	1,850,713	$	796,805	132	%
Less: Acquired loan and securities accretion - rate related	l=b+f+i	166,182		3,290		nm
Less: Acquired loan accretion - credit related	c	17,276		—		nm
Adjusted interest income (1)	m=k-l-c	$	1,667,255	$	793,515	110	%
Interest-bearing deposits interest expense	n	$	290,995	$	17,021	nm
Less: Acquired deposit accretion	o	(746)		—		nm
Adjusted interest-bearing deposits interest expense	p=n-o	$	291,741	$	17,021	nm
Interest expense	q	$	508,145	$	31,233	nm
Less: Acquired interest-bearing liabilities accretion (2)	r	(917)		(171)		436	%
Adjusted interest expense	s=q-r	$	509,062	$	31,404	nm
Net Interest Income (1)	t	$	1,342,568	$	765,572	75	%
Less: Acquired loan, securities, and interest-bearing liabilities accretion - rate related (3)	u=l-r	167,099		3,461		nm
Less: Acquired loan accretion - credit related (3)	c	17,276		—		nm
Adjusted net interest income (1)	v=t-u-c	$	1,158,193	$	762,111	52	%
Average loans and leases	aa	34,765,319		23,676,201		47	%
Average taxable securities	ab	7,336,862		3,445,386		113	%
Average non-taxable securities	ac	717,064		222,375		222	%
Average interest-earning assets	ad	45,203,459		29,303,722		54	%
Average interest-bearing deposits	ae	23,091,034		15,422,795		50	%
Average interest-bearing liabilities	af	28,510,120		16,355,258		74	%

(1)Tax exempt interest has been adjusted to a taxable equivalent basis using a 21% tax rate.

(2)Includes discount accretion related to UHC's 2014 acquisition of Sterling Financial Corporation.

(3)The cumulative fair value discount on historical Columbia loans was established as of February 28, 2023, and the allocation between the credit-related discount and the rate-related discount was established at that time. Our disclosure of credit-related and rate-related discount accretion is an estimate based on the relative allocation of these two items to the discount at closing. 

Columbia Banking System, Inc. Reports Third Quarter 2023 Results

October 18, 2023

Page 28

Columbia Banking System, Inc.
GAAP to Non-GAAP Reconciliation - Continued
(Unaudited)
($ in thousands)		Sep 30, 2023		Sep 30, 2022		Year over Year
Average yield on loans and leases	a / aa	5.88	%	4.06	%	1.82
Less: Acquired loan accretion - rate related (2),(3)	b / aa	0.27	%	0.02	%	0.25
Less: Acquired loan accretion - credit related (3)	c / aa	0.07	%	—	%	0.07
Adjusted average yield on loans and leases	d / aa	5.54	%	4.04	%	1.50
Average yield on taxable securities	e / ab	3.76	%	2.11	%	1.65
Less: Acquired taxable securities accretion - rate related	f / ab	1.63	%	—	%	1.63
Adjusted average yield on taxable securities	g / ab	2.13	%	2.11	%	0.02
Average yield on non-taxable securities (1)	h / ac	3.75	%	3.06	%	0.69
Less: Acquired non-taxable securities accretion - rate related	i / ac	1.02	%	—	%	1.02
Adjusted yield on non-taxable securities (1)	j / ac	2.73	%	3.06	%	(0.33)
Average yield on interest-earning assets (1)	k / ad	5.46	%	3.62	%	1.84
Less: Acquired loan and securities accretion - rate related	l / ad	0.49	%	0.02	%	0.47
Less: Acquired loan accretion - credit related	c / ad	0.05	%	—	%	0.05
Adjusted average yield on interest-earning assets (1)	m / ad	4.92	%	3.60	%	1.32
Average rate on interest-bearing deposits	n / ae	1.68	%	0.15	%	1.53
Less: Acquired deposit accretion	o / ae	—	%	—	%	—
Adjusted average rate on interest-bearing deposits	p / ae	1.68	%	0.15	%	1.53
Average rate on interest-bearing liabilities	q / af	2.38	%	0.26	%	2.12
Less: Acquired interest-bearing liabilities accretion (2)	r / af	—	%	—	%	—
Adjusted average rate on interest-bearing liabilities	s / af	2.38	%	0.26	%	2.12
Net interest margin (1)	t / ad	3.96	%	3.48	%	0.48
Less: Acquired loan, securities, and interest-bearing liabilities accretion - rate related (3)	u / ad	0.49	%	0.02	%	0.47
Less: Acquired loan accretion - credit related (3)	c / ad	0.05	%	—	%	0.05
Adjusted net interest margin (1)	v / ad	3.42	%	3.46	%	(0.04)

(1)Tax exempt interest has been adjusted to a taxable equivalent basis using a 21% tax rate.

(2) Includes discount accretion related to UHC's 2014 acquisition of Sterling Financial Corporation.

(3)The cumulative fair value discount on historical Columbia loans was established as of February 28, 2023, and the allocation between the credit-related discount and the rate-related discount was established at that time. Our disclosure of credit-related and rate-related discount accretion is an estimate based on the relative allocation of these two items to the discount at closing. 

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 1995, which management believes are a benefit to shareholders. These statements are necessarily subject to risk and uncertainty and actual results could differ materially due to various risk factors, including those set forth from time to time in our filings with the Securities and Exchange Commission (the "SEC"). You should not place undue reliance on forward-looking statements and we undertake no obligation to update any such statements. Forward-looking statements can be identified by words such as "anticipates," "intends," "plans," "seeks," "believes," "estimates," "expects," "target," "projects," "outlook," "forecast," "will," "may," "could," "should," "can" and similar references to future periods. In this presentation we make forward-looking statements about strategic and growth initiatives and the result of such activity. Risks that could cause results to differ from forward-looking statements we make include, without limitation: current and future economic and market conditions, including the effects of declines in housing and commercial real estate prices, high unemployment rates, continued inflation and any recession or slowdown in economic growth particularly in the western United States; economic forecast variables that are either materially worse or better than end of quarter projections and deterioration in the economy that could result in increased loan and lease losses, especially those risks associated with concentrations in real estate related loans; our ability to effectively manage problem credits; the impact of bank failures or adverse developments at or news developments concerning other banks on general investor sentiment regarding the liquidity and stability of banks; changes in interest rates that could significantly reduce net interest income and negatively affect asset yields and valuations and funding sources; changes in the scope and cost of FDIC insurance and other coverage; our ability to successfully implement efficiency and operational excellence initiatives; our ability to successfully develop and market new products and technology; changes in laws or regulations; any failure to realize the anticipated benefits of the UHC merger when expected or at all; the possibility that the integration following the UHC merger may be more expensive than anticipated, including as a result of unexpected factors or events, diversion of management’s attention from ongoing business operations and opportunities; potential adverse reactions or changes to business or employee relationships, including those resulting from the completion of the UHC merger and integration of the companies; the effect of geopolitical instability, including wars, conflicts and terrorist attacks; and natural disasters and other similar unexpected events outside of our control. We also caution that the amount and timing of any future common stock dividends or repurchases will depend on the earnings, cash requirements and financial condition of Columbia, market conditions, capital requirements, applicable law and regulations (including federal securities laws and federal banking regulations), and other factors deemed relevant by Columbia's Board of Directors, and may be subject to regulatory approval or conditions. NON-GAAP FINANCIAL MEASURES In addition to results in accordance with GAAP, this presentation contains certain non-GAAP financial measures. A reconciliation of GAAP to non-GAAP measures is included in the Appendix. We believe presenting certain non-GAAP financial measures provides investors with information useful in understanding our financial performance, our performance trends, and our financial position. We utilize these measures for internal planning and forecasting purposes. We, as well as securities analysts, investors, and other interested parties, also use these measures to compare peer company operating performance. We believe that our presentation and discussion, together with the accompanying reconciliations, provide a complete understanding of factors and trends affecting our business and allows investors to view performance in a manner similar to management. These non-GAAP measures should not be considered a substitution for GAAP basis measures and results, and we strongly encourage investors to review our consolidated financial statements in their entirety and not to rely on any single financial measure. Because non-GAAP financial measures are not standardized, it may not be possible to compare these financial measures with other companies’ non-GAAP financial measures having the same or similar names. REVERSE ACQUISITION METHOD OF ACCOUNTING On February 28, 2023, Columbia Banking System, Inc. ("Columbia", "we" or "our") completed its merger (the “merger” or the “UHC Merger”) with Umpqua Holdings Corporation ("UHC"). Columbia's financial results for any periods ended prior to February 28, 2023 reflect UHC results only on a standalone basis unless explicitly stated otherwise. In addition, Columbia's reported financial results for the first quarter of 2023 reflect UHC financial results only until the closing of the merger after the close of business on February 28, 2023. As a result of these two factors, Columbia's financial results for the first, second, and third quarters of 2023 and the nine months ended September 30, 2023 may not be directly comparable to prior reported periods. The number of shares issued and outstanding, earnings per share, additional paid-in capital, and all references to share quantities or metrics of Columbia have been retrospectively restated to reflect the equivalent number of shares issued in the merger as the merger was treated as a reverse merger. Under the reverse acquisition method of accounting, the assets and liabilities of Columbia as of February 28, 2023 ("historical Columbia") were recorded at their respective fair values. 2

FINANCIAL HIGHLIGHTS AND SUMMARY FINANCIAL STATEMENTS Q3 2023

Performance Ratios Footnotes: (1) Tax exempt interest has been adjusted to a taxable equivalent basis using a 21% tax rate. (2) Non-GAAP financial measure. A reconciliation to the comparable GAAP measurement is provided at the end of this slide presentation. (3) Operating results include the initial provision in Q1 2023 related to non-PCD loans added through the merger, and reported results further include merger-related expense. These items meaningfully impact performance ratios where applicable. For the Quarter Ended Q3 2023 Q2 2023 Q1 2023 Q4 2022 Q3 2022 Reported (3) Net interest margin (1) 3.91 % 3.93 % 4.08 % 4.01 % 3.88 % Efficiency ratio (1) 57.82 % 62.60 % 79.71 % 57.24 % 56.07 % Return on average assets 1.02 % 1.00 % (0.14) % 1.04 % 1.09 % Pre-provision net revenue (PPNR) return on average assets (2) 1.65 % 1.46 % 0.89 % 1.82 % 1.80 % Return on average common equity 11.07 % 10.84 % (1.70) % 13.50 % 12.99 % Return on average tangible common equity (2) 16.93 % 16.63 % (2.09) % 13.53 % 13.02 % Operating (3) Operating efficiency ratio (1), (2) 51.97 % 54.85 % 53.46 % 52.01 % 51.72 % Operating return on average assets (2) 1.23 % 1.27 % 0.74 % 1.24 % 1.33 % Operating PPNR return on average assets (2) 1.94 % 1.82 % 2.01 % 2.10 % 2.12 % Operating return on average common equity (2) 13.40 % 13.77 % 8.66 % 16.14 % 15.86 % Operating return on average tangible common equity (2) 20.48 % 21.13 % 10.64 % 16.18 % 15.90 % Q3 2023 Highlights (compared to Q2 2023) ■ Net interest margin decreased 2 basis points to 3.91%. The second full quarter as a combined organization, higher customer balances, and consistent purchase accounting trends contributed to net interest margin stabilization between quarters. ■ Improved efficiency and pre-provision profitability reflect the realization of cost synergies and a smaller impact from merger-related expense. ■ Return on assets (“ROA”) and return on average tangible common equity (“ROTCE”) were 1.02% and 16.9% on a reported basis and 1.23% and 20.5% on an operating basis. 4

Selected Period-End Balance Sheet Footnotes: Tables may not foot due to rounding. (1) Periods prior to February 28, 2023, have been restated as a result of the adjustment to common shares outstanding based on the exchange ratio from the UHC merger of 0.5958. (2) Non-GAAP financial measure. A reconciliation to the comparable GAAP measurement is provided in the appendix of this slide presentation. ($ in millions, except per-share data) Q3 2023 Q2 2023 Q1 2023 Q4 2022 Q3 2022 ASSETS: Total assets $51,989.6 $53,592.1 $53,994.2 $31,848.6 $31,472.0 Interest bearing cash and temporary investments 1,911.2 2,868.6 3,079.3 967.3 1,232.4 Investment securities available for sale, fair value 8,504.0 8,998.4 9,249.6 3,196.2 3,136.4 Loans and leases, gross 37,170.6 37,049.3 37,091.3 26,156.0 25,508.0 Allowance for credit losses on loans and leases (416.6) (404.6) (417.5) (301.1) (283.1) Goodwill and other intangibles, net 1,666.1 1,696.0 1,732.5 4.7 5.8 LIABILITIES AND EQUITY: Deposits 41,624.4 40,834.9 41,586.3 27,065.6 26,817.1 Securities sold under agreements to repurchase 258.4 294.9 271.0 308.8 383.6 Borrowings 3,985.0 6,250.0 5,950.0 906.2 756.2 Total shareholders' equity 4,632.2 4,828.2 4,884.7 2,479.8 2,417.5 RATIOS AND PER-SHARE METRICS: Loan to deposit ratio 89.3% 90.7% 89.2% 96.6% 95.1% Book value per common share (1) $22.21 $23.16 $23.44 $19.18 $18.69 Tangible book value per common share (1), (2) $14.22 $15.02 $15.12 $19.14 $18.65 Tangible common equity to tangible assets (2) 5.9% 6.0% 6.0% 7.8% 7.7% 5 Q3 2023 Highlights (compared to Q2 2023) ■ Net loan growth of $121 million in Q3 2023 was impacted by the sale of $159 million in non-relationship jumbo residential mortgage loans during the quarter. ■ Excess cash and the addition of brokered deposits were used to pay off maturing FHLB advances, which declined by $2.3 billion to $4.0 billion at quarter end. Customer deposit balances increased slightly between September 30, 2023 and June 30, 2023. ■ Q1 2023 results were impacted by the closing of the merger on February 28, 2023 and the addition of historical Columbia balances at fair value.

Summary Income Statement Footnotes: Tables may not foot due to rounding. (1) Periods prior to February 28, 2023, have been restated as a result of the adjustment to common shares outstanding based on the exchange ratio from the UHC merger of 0.5958. (2) Non-GAAP financial measure. A reconciliation to the comparable GAAP measurement is provided at the end of this slide presentation. For the Quarter Ended ($ in millions, except per-share data) Q3 2023 Q2 2023 Q1 2023 Q4 2022 Q3 2022 Net interest income before provision $480.9 $484.0 $374.7 $305.5 $287.6 Provision for credit losses 36.7 16.0 105.5 32.9 27.6 Net interest income after provision 444.1 468.0 269.2 272.5 260.0 Non-interest income 44.0 39.7 54.7 34.9 29.4 Non-interest expense 304.1 328.6 342.8 195.0 178.0 Income (loss) before provision (benefit) for income taxes 184.0 179.1 (18.9) 112.4 111.5 Provision (benefit) for income taxes 48.1 45.7 (4.9) 29.5 27.5 Net income (loss) $135.8 $133.4 ($14.0) $83.0 $84.0 Earnings (loss) per share, diluted (1) $0.65 $0.64 ($0.09) $0.64 $0.65 Non-interest expense, excluding merger-related expense (2) $285.2 $299.0 $226.9 $183.3 $177.2 Pre-provision net revenue (2) $220.7 $195.1 $86.6 $145.4 $139.1 Operating pre-provision net revenue (2) $258.7 $243.1 $195.7 $167.1 $163.8 Operating net income (2) $164.3 $169.4 $71.5 $99.2 $102.6 Operating earnings per share, diluted (1), (2) $0.79 $0.81 $0.46 $0.76 $0.79 6 Q3 2023 Highlights (compared to Q2 2023) ■ Net interest income decreased by $3 million as the increase in interest income due to higher yields was more than offset by higher funding costs. ■ Non-interest income increased by $4 million due to higher customer-related fee income and loan gain-on-sale income as well as a lower loss due to cumulative non-merger fair value accounting and hedges. ■ Excluding merger-related expense, non- interest expense declined by $14 million due to cost synergies. Non-interest expense declined by $24 million on a reported basis. ■ Provision expense relates to portfolio mix changes and credit migration trends. ■ Q1 2023 results include only one month of the combined company’s operations and a related initial provision of $88 million.

Income Statement Component Details For the Quarter Ended September 30, 2023 LESS: EQUALS LESS: EQUALS ($ in thousands, except per-share data) GAAP Income Non-Operating Items (1) Operating Income (2) Merger-Related Items (3) Adjusted Operating Income (2) Interest income $696,013 $— $696,013 $76,840 $619,173 Interest expense 215,138 — 215,138 (430) 215,568 Net interest income 480,875 — 480,875 77,270 403,605 Provision for credit losses 36,737 — 36,737 — 36,737 Net interest income after provision 444,138 — 444,138 77,270 366,868 Non-interest income 43,981 (15,023) 59,004 — 59,004 Non-interest expense 304,147 22,955 281,192 29,879 251,313 Income before provision for income taxes 183,972 (37,978) 221,950 47,391 174,559 Provision for income taxes 48,127 (9,482) 57,609 11,848 45,761 Net income $135,845 ($28,496) $164,341 $35,543 $128,798 Revenue $524,856 ($15,023) $539,879 $77,270 $462,609 Pre-provision net revenue (2) $220,709 ($37,978) $258,687 $47,391 $211,296 Net interest margin (4) 3.91 % NA 3.91 % 0.63 % 3.28 % Efficiency ratio (4) 57.82 % 5.85 % 51.97 % (2.22) % 54.19 % PPNR return on assets (2) 1.65 % (0.29) % 1.94 % 0.36 % 1.58 % Return on assets 1.02 % (0.21) % 1.23 % 0.27 % 0.96 % Return on equity 11.07 % (2.33) % 13.40 % 2.90 % 10.50 % Return on tangible common equity (2) 16.93 % (3.55) % 20.48 % 4.43 % 16.05 % Earnings per share, diluted $0.65 ($0.14) $0.79 $0.17 $0.62 7 Q3 2023 Highlights ■ GAAP results were adversely impacted by 14 cents of non-operating items that include cumulative fair value adjustments, hedging activity, and merger-related expense. PAA and CDI amortization provided a net benefit of 17 cents to EPS. ■ Operating EPS of $0.79 resulted in a return on assets of 1.23% and a return on tangible common equity of 20.5%. ■ We expect the net impact of merger- related items (PAA and CDI amortization) to continue to add to EPS as a steady and reliable source of income over time as it is primarily driven by rate, not credit. We expect this net earnings stream to build capital over time. ■ See appendix for five-quarter comparison data for each income component. Footnotes: (1) Non-operating income and expense items are detailed at the end of this slide presentation. Non-operating expense includes $19 million of merger-related expense. (2) All items in this column represent non-GAAP financial measures and should be reviewed alongside the GAAP reconciliation in this table. PPNR, PPNR return on assets, and return on tangible common equity are also non-GAAP measures for all ratios presented, including those in the GAAP column; a reconciliation is provided at the end of this presentation. (3) Merger-related items include purchase accounting accretion and amortization (PAA) captured in interest income and interest expense and CDI amortization of $30 million. (4) Tax exempt interest has been adjusted to a taxable equivalent basis using a 21% tax rate and is included in the calculation of this ratio.

INCOME STATEMENT HIGHLIGHTS Q3 2023

Net Interest Income and Net Interest Margin Footnotes: (1) Chart Abbreviations: “LHFI” = loans held for investment. $ in m ill io ns Net Interest Income and Net Interest Margin $288 $305 $375 $484 $481 3.88% 4.01% 4.08% 3.93% 3.91% Net Interest Income Net Interest Margin Q3 2022 Q4 2022 Q1 2023 Q2 2023 Q3 2023 $— $100 $200 $300 $400 $500 3.00% 3.50% 4.00% 4.50% 5.00% Net Interest Margin: Q2 2023 vs Q3 2023 3.93% 0.12% (0.03)% 0.05% 0.01% (0.20)% 0.04% (0.01)% 3.91% Q2 2023 Reported LHFI-ex PAA¹ LHFI- PAA¹ Invest- ments Interest- Bearing Cash Deposits Term Debt Other Inputs Q3 2023 Reported 9 ■ Net interest margin was 3.91% in Q3 2023, down 2 basis points from the prior quarter as higher yields on loans and investments did not fully offset higher funding costs. ■ The cost of interest-bearing deposits increased 37 basis points on a linked-quarter basis to 2.01% in Q3 2023, which compares to 2.18% for the month of September and 2.27% at September 30, 2023. Deposit costs were impacted by the decision to replace a portion of maturing FHLB advances with brokered deposits, which increased the cost of deposits but was fairly neutral to the cost of interest-bearing liabilities. ■ The cost of interest-bearing liabilities increased 27 basis points on a linked-quarter basis to 2.72% in Q3 2023, which compares to 2.77% for the month of September and 2.78% at September 30, 2023.

Loan Repricing Detail (1), (2) ($ in millions) Q2 2023 Q3 2023 Q2 2023 Q3 2023 Fixed $15,806 $15,793 42 % 42 % Prime 2,897 2,820 8 % 7 % 1 Month 7,451 8,214 20 % 22 % Floating 10,348 11,034 28 % 29 % Prime 430 386 1 % 1 % 1 Month 274 105 1 % — % 6 Month 5,883 5,733 16 % 15 % 1 Year 1,293 1,285 3 % 3 % 3 Year 425 227 1 % 1 % 5 Year 2,269 2,273 6 % 6 % 10 Year 937 949 2 % 3 % Adjustable 11,511 10,958 30 % 29 % Total $37,665 $37,785 100 % 100 % Loan Maturities at September 30, 2023 <=6 7 to 12 13 to 24 25 to 36 37 to 60 61+ ($ in millions) Months Months Months Months Months Months Total Fixed $1,919 $223 $601 $880 $2,210 $9,960 $15,793 Floating 1,564 1,170 1,211 803 1,415 4,871 11,034 Adjustable 55 45 208 273 673 9,704 10,958 Total $3,538 $1,438 $2,020 $1,956 $4,298 $24,535 $37,785 Interest Rate Sensitivity: Loans Floors: Floating and Adjustable Rate Loans at September 30, 2023 ($ in millions) No Floor (3) At Floor (3) Above Floor (3) Total Floating $6,665 $16 $4,353 $11,034 Adjustable 1,766 6 9,186 10,958 Total $8,431 $22 $13,539 $21,992 % of Total 38% —% 62% 100% 10 Footnotes: (1) Index rates are mapped to the closest material index. (2) Loan totals on this slide do not include purchase accounting adjustments. Deferred fees and costs also drive variances between loan totals on this slide and loan totals in the earnings press release. (3) Loans were grouped into three buckets: (1) No Floor: no contractual floor on the loan; (2) At Floor: current rate = floor; (3) Above Floor: current rate exceeds floor. The amount above the floor was based on the current margin plus the current index assuming the loan repriced on September 30, 2023. The adjustable loans may not reprice until well into the future, depending on the timing and size of interest rate changes.

Interest Rate Sensitivity: Balance Sheet Interest Rate Simulation Impact on Net Interest Income (1), (2) September 30, 2023 June 30, 2023 September 30, 2022 Ramp Shock Ramp Shock Ramp Shock Year 1 Year 2 Year 1 Year 2 Year 1 Year 2 Year 1 Year 2 Year 1 Year 2 Year 1 Year 2 Up 200 basis points (0.4)% 0.7% (1.0)% 2.1% (0.8)% (0.7)% (1.3)% 0.6% 2.0% 6.8% 4.5% 8.6% Up 100 basis points (0.2)% 0.4% (0.5)% 1.1% (0.4)% (0.3)% (0.7)% 0.3% 1.0% 3.5% 2.3% 4.3% Down 100 basis points (1.3)% (3.4)% (2.4)% (4.1)% (0.8)% (2.1)% (1.0)% (1.8)% (3.1)% (7.8)% (6.4)% (8.8)% Down 200 basis points (2.7)% (7.1)% (5.2)% (8.7)% (1.5)% (4.3)% (3.1)% (5.0)% (6.5)% (16.1)% (13.6)% (18.0)% Down 300 basis points (4.0)% (11.0)% (7.9)% (13.5)% (2.4)% (6.9)% (5.6)% (8.6)% (10.2)% (23.5)% (19.9)% (26.2)% Footnotes: (1) For the scenarios shown, the interest rate simulations assume a parallel and sustained shift in market interest rates ratably over a twelve-month period (ramp) or immediately (shock). There is no change in the composition or the size of the balance sheet in either scenario. Interest rate sensitivity in the first year of the net interest income simulation for increasing interest rate ramp scenarios is negatively impacted by the cost of non-maturity deposits repricing immediately while interest earning assets reprice at a slower rate. (2) The simulation repricing beta applied to interest-bearing deposits in the rising rate scenarios is 54% for September 30, 2023, 53% for June 30, 2023, and 51% for September 30, 2022. Betas applied are for future repricing assuming future rate changes, and the simulations assume an immediate repricing impact. Note that interest rate simulations present data on a legal company basis: Data displayed at September 30, 2023 and June 30, 2023 represent the combined company and data displayed at September 30, 2022 represent historical UHC data only. ■ While the use of brokered deposits increased Columbia’s cumulative interest-bearing deposit beta to 37% in Q3 2023 from 31% in Q2 2023, the total funding beta experienced a smaller movement to 33% from 31% over the period as brokered balances were used to pay off maturing FHLB advances. ■ We continue to manage the balance sheet to protect its sensitivity to a declining interest rate environment as this scenario presents more risk to net interest income than a “higher-for-longer” interest rate scenario. 11 Deposit and Funding Repricing Betas During the Current Rising-Rate Cycle** Effective Fed Funds Rate (Daily Avg.) Cost of Combined Company** Interest- Bearing Deposits Total Deposits Total Funding Q3 2023 5.26% 2.01% 1.23% 1.81% Q2 2023 4.99% 1.64% 0.99% 1.61% Q1 2023 4.52% 1.32% 0.80% 1.16% Q4 2022 3.65% 0.62% 0.35% 0.51% Q3 2022 2.20% 0.22% 0.12% 0.18% Q2 2022 0.76% 0.11% 0.06% 0.10% Q1 2022 0.12% 0.09% 0.05% 0.08% Q4 2021 0.08% 0.10% 0.05% 0.09% Variance: Peak (Peak Value less Q4 2021) +5.18% +1.91% +1.18% +1.72% Beta - Cycle-to-Date 37% 23% 33% **Note: Deposit and funding repricing beta data present combined company results as if historical Columbia and historical UHC were one company for all periods through December 31, 2022; subsequent quarters present data on a legal basis given the merger. The beta presentation is calculated in this manner for comparison purposes.

Non-Interest Income Footnotes: Tables may not foot due to rounding. (1) Commercial product revenue includes swaps, syndication, and international banking revenue, which are captured in “other income” on the income statement. Other income statement line items, like card-based fees, include other sources of commercial product revenue. For the quarter ended ($ in millions) Q3 2023 Q2 2023 Q1 2023 Q4 2022 Q3 2022 Service charges on deposits $17.4 $16.5 $14.3 $12.1 $12.6 Card-based fees 15.7 13.4 11.6 9.0 9.1 Financial services and trust revenue 4.7 4.5 1.3 — — Residential mortgage banking revenue, net 7.1 (2.3) 7.8 (1.8) 17.3 Loss (gain) on equity securities, net (2.1) (0.7) 2.4 0.3 (2.6) Gain on loan and lease sales, net 1.9 0.4 0.9 1.5 1.5 BOLI income 4.4 4.1 2.8 2.0 2.0 Other Income Commercial product revenue (1) $3.0 $3.0 $1.4 $5.3 $6.4 Commercial servicing revenue 0.5 0.4 0.9 0.9 0.7 Loan-related fees 3.6 3.3 3.4 3.2 3.2 Change in fair value of certain loans held for investment (19.2) (7.0) 9.5 4.2 (26.4) Misc. Income 1.3 2.8 1.9 0.4 1.3 Swap derivative gain (loss) 5.7 1.3 (3.5) (2.3) 4.2 12 Q3 2023 Highlights (compared to Q2 2023) ■ Revenue from customer-related products increased during the quarter as we continue to target balanced loan, deposit, and fee income growth. ■ Mortgage banking revenue increased as Q2 2023’s results were adversely impacted by the ineffectiveness of mortgage servicing rights (“MSR”) hedges during the quarter due to the planned sale of approximately one-third of the MSR portfolio and the associated accounting treatment. The transaction closed in Q3 2023 with no income statement impact. ■ Q1 2023 results include only one month of the combined company’s operations.

Realized Cost Synergies Exceeded Original Target 13 Annualized Cost Synergies Realized by Period End Q4 2022 Q1 2023 Q2 2023 Q3 2023 Q4 2023 $— $50 $100 $150 $200 $30 million(1) $59 million(1) $105 million(1) $140 million(1) ■ We realized $140 million in annualized cost synergies through September 30, 2023(1), exceeding our original $135 million target. We will realize the remaining merger-related savings in 2023, which include an additional $3 million in identified annualized savings to be achieved in Q4 2023(1). ■ There are additional opportunities to realize operational efficiencies in 2024 and beyond. We will continue to manage our expense base and seek out these offsets to fund growth-driven reinvestment. ■ Cost synergies realized ahead of the February 28, 2023 merger close were primarily driven by departing associates that were not slated to be part of the go-forward organization, though there were some real estate and contract-related savings achieved as well in anticipation of closing. The core systems conversion was completed March 20, 2023, and 47 branches were consolidated in the latter half of Q2 2023. (1) Realized synergies are annualized and reflect what is achieved or expected to be achieved at the end of the quarter; the full amount is not included in the full-quarter run rate. ~$143 million(1) $ in m ill io ns Non-Interest Expense ("NIE"): Q2 2023 vs Q3 2023 $328.6 $(4.4) $(2.1) $(1.2) $(4.1) $1.9 $(10.7) $(3.9) $304.1 Q2 2023 NIE Salaries & Benefits Software Costs Maint. Contracts Other Occup. & Equip Exit & Disposal Costs Merger- Related Expense Other Q3 2023 NIE

Outlook (1) Nine months ended September 30, 2023 and Full-Year 2023 impacted by the February 28, 2023 merger close. (2) Non-GAAP basis; see reconciliation on slide 7. Excludes non-operating and merger-related items. (3) The cumulative fair value discount on historical Columbia loans was established as of February 28, 2023, and the allocation between the credit-related discount and the rate-related discount was established at that time. Our disclosure of credit-related and rate-related discount accretion is an estimate based on the relative allocation of these two items to the discount at closing. Results (1) Full-Year 2023 Outlook (1) Three Months Ended Nine Months Ended Sept 30, 2023 Sept 30, 2023 As of July 19, 2023 As of Oct 18, 2023 Notes Average earning assets $49b $45b $45b - $46b $45b - $46b Assumes cash balance at 9/30 remains consistent through remainder of 2023 Net interest margin - GAAP 3.91% 3.96% 3.75% - 3.95% 3.85% - 3.95% Forward outlook does not include any additional changes to the fed funds rate in 2023; incorporates purchase accounting income detailed below and a range of funding flows in Q4 that assume customer deposit balance growth at the upper end of the NIM range and contraction at the lower end of the NIM range Purchase accounting accretion - securities; rate related (3) $42mm $95mm $115mm - $125mm $125mm - $130mm Assumes very low prepayment activity; an increase in payoff or paydown speeds would increase income Purchase accounting accretion - loans; rate related (3) $29mm $71mm $98mm - $106mm $98mm - $106mm Purchase accounting accretion - loans; credit related (3) $6mm $17mm $22mm - $24mm $22mm - $24mm Non-interest expense - excluding CDI and merger-related expense (2) $251mm $726mm $965mm - $980mm $965mm - $975mm We continue to anticipate a Q4 run rate of $240mm - $250mm (not annualized) excluding CDI amortization, merger-related expense, and the estimated FDIC special assessment, the timing of which is not yet known CDI amortization $30mm $78mm ~$116mm ~$111mm Not included in adjusted non-interest expense detailed above Merger-related expense $19mm $164mm ~$160mm ~$170mm Not included in adjusted non-interest expense detailed above 14

BALANCE SHEET HIGHLIGHTS Q3 2023

Available for Sale Securities Portfolio at September 30, 2023 ($ in millions) Current Par Amortized Cost Unrealized Gains Unrealized Losses Fair Value % of Total AFS Portfolio Effective Duration Book Yield U.S. Treasuries $392 $378 $— ($12) $366 4 % 2.6 3.55 % U.S. Agencies 1,162 1,179 — (108) $1,071 13 % 4.4 2.80 % Mortgage-backed securities - residential agency 3,274 3,054 — (416) $2,638 31 % 7.1 3.23 % Collateralized mortgage obligations (1) 1,416 1,323 — (154) $1,169 14 % 6.1 3.41 % Obligations of states and political subdivisions 1,138 1,075 — (76) $999 12 % 5.4 3.37 % Commercial mortgage-backed securities - agency 2,542 2,371 — (110) $2,261 27 % 4.8 4.72 % Total available for sale securities $9,924 $9,380 $— ($876) $8,504 5.7 3.61 % Percentage of Current Par 95 % — % (9) % 86 % 16 Securities Portfolio Overview (1) Portfolio includes $260 million in high-quality non-agency collateralized mortgage obligations (“CMO”) that were in a small unrealized loss position at September 30, 2023 (amortized cost of $274 million). The remaining $1.2 billion of the portfolio is comprised of residential agency CMOs. ■ The total AFS securities portfolio had a book yield of 3.61% and an effective duration of 5.7 at September 30, 2023, essentially unchanged from June 30, 2023. ■ Outside of equity securities, all securities were classified as AFS and carried on the balance sheet at fair value at September 30, 2023, with exception of $2.3 million in local community housing bonds classified as held to maturity; there is no unrealized loss associated with this portfolio, which was 0.03% of total securities.

Liquidity Overview Select Balance Sheet Items: Combined Basis Pre-Closing and Consolidated Basis Post-Closing (1) Three Months Ended Sequential Quarter Change ($ in millions) Q3 2023 Q2 2023 Q1 2023 Q4 2022 Q3 2023 Required divestitures - associated deposits $— $— $— $547 $— Brokered deposits 3,122 2,346 1,630 867 776 Administrative 146 239 183 112 (93) Public deposits 2,442 2,425 2,556 2,758 17 Customer accounts 35,914 35,825 37,217 39,457 89 Total Deposits $41,624 $40,835 $41,586 $43,741 $789 Repurchase agreements $258 $295 $271 $404 ($37) Term debt $3,985 $6,250 $5,950 $1,860 ($2,265) Cash and cash equivalents $2,404 $3,407 $3,635 $1,589 ($1,003) Securities(2) $8,506 $9,001 $9,252 $9,832 ($495) Loans $37,171 $37,049 $37,091 $37,759 $122 Total Available Liquidity at September 30, 2023 ($ in millions) Total off-balance sheet liquidity (available lines of credit): $12,216 Cash and equivalents, less reserve requirement 2,014 Excess bond collateral 4,842 Total available liquidity $19,072 TOTAL AVAILABLE LIQUIDITY AS A PERCENTAGE OF: Assets of $52.0 billion at September 30, 2023 37 % Deposits of $41.6 billion at September 30, 2023 46 % Uninsured deposits of $13.5 billion at September 30, 2023 142 % Total Off-Balance Sheet Liquidity Available at September 30, 2023 ($ in millions) Gross Availability Utilization Net Availability FHLB lines $11,955 $3,970 $7,985 Federal Reserve Discount Window 1,677 — 1,677 Federal Reserve Term Funding Program 1,954 — 1,954 Uncommitted lines of credit 600 — 600 Total off-balance sheet liquidity $16,186 $3,970 $12,216 17 ■ We began to reduce our cash position during 3Q 2023 given stabilizing industry trends and ample sources of available liquidity. Excess cash and brokered deposits were used to fund maturing FHLB advances during the quarter. ■ Customer deposit balances stabilized during 3Q 2023 despite continued market liquidity tightening, the impact of inflation on customer spending, and businesses’ use of cash. ■ Uninsured deposits were $13.5 billion at September 30, 2023, representing 32% of total deposits. Available liquidity of $19.1 billion was 142% of uninsured deposits at that time. (1) All data presented in the above table combine historical Columbia data and historical UHC data for the three months ended December 31, 2022 (before the merger’s February 28, 2023 close) to provide a consistent comparison of the changes that occurred when viewing the combined organization. (2) Available-for-sale and held-to-maturity securities. Held to maturity securities were only 0.03% of the portfolio at September 30, 2023 and relate to local community housing bonds.

Loan Roll Forward Activity $ in m ill io ns Three Months Ended September 30, 2023 $37,049 $1,042 ($92) ($515) ($343) $30 $37,171 Beginning Balance (6/30/23) New Originations Net Advances/ Payments Prepayments Payoffs or Sales Other Ending Balance (9/30/23) 18 Footnotes: Other includes purchase accounting accretion and amortization. $ in m ill io ns Nine Months Ended September 30, 2023 $26,156 $10,884 $3,006 ($237) ($1,444) ($1,268) $74 $37,171 Beginning Balance (12/31/22) Merger New Originations Net Advances/ Payments Prepayments Payoffs or Sales Other Ending Balance (9/30/23) $ in m ill io ns Three Months Ended September 30, 2022 $24,433 $1,745 $173 ($675) ($142) ($26) $25,508 Beginning Balance (6/30/22) New Originations Net Advances/ Payments Prepayments Payoffs or Sales Other Ending Balance (9/30/22) $ in m ill io ns Nine Months Ended September 30, 2022 $22,553 $5,805 $300 ($2,629) ($492) ($29) $25,508 Beginning Balance (12/31/21) New Originations Net Advances/ Payments Prepayments Payoffs or Sales Other Ending Balance (9/30/22)

Purchase Accounting Details (1) Table does not capture all assets and liabilities with an associated fair value discount or premium. Assets and liabilities not presented have a significantly smaller impact on income through the accretion or amortization of their discount or premium. (2) See slide 14 for near-term interest income and non-interest expense expectations related to the items outlined in this table. (3) The cumulative fair value discount on historical Columbia loans was established as of February 28, 2023, and the allocation between the credit-related discount and the rate-related discount was established at that time. Our disclosure of credit-related and rate-related discount accretion is an estimate based on the relative allocation of these two items to the discount at closing. Adjustment at Closing Remaining Balances at Select Purchase Accounting Items (1) February 28, 2023 June 30, 2023 September 30, 2023 (2) Notes ITEMS TO ACCRETE THROUGH INTEREST INCOME: Available for sale securities - rate discount $(1,011) million $(609) million $(586) million While an adjustment to historical Columbia securities’ book value was $1.0 billion at closing, the purchase discount that will accrete into interest income over time was $0.6 billion when previously existing purchase premiums and the discount associated with bonds sold as part of the Q1 2023 portfolio restructuring were eliminated. Loans - rate discount (3) $(618) million $(558) million $(496) million Purchase accounting related to loans sold during Q3 2023 caused a larger reduction in the purchase discount than what was booked through interest income during the quarter. Total rate discount on loans and securities $(1,629) million $(1,167) million $(1,082) million Loans - credit mark (3) $(130) million $(94) million $(86) million Total discount on loans and securities $(1,759) million $(1,261) million $(1,168) million Fair value discounts are accreted into interest income using the effective interest method, which amortizes the discount over the life of the loan or security. ITEM TO AMORTIZE THROUGH NON-INTEREST EXPENSE: Core deposit intangible $710 million $664 million $635 million CDI amortizes through non-interest expense over 10 years using the sum-of-the-years-digits method. 19

Loan and Lease Characteristics: Overall Portfolio and Q3 2023 Production Footnotes: Portfolio statistics and delinquencies as of September 30, 2023. Annualized net charge-off rate for Q3 2023. Loan-to-value (“LTV”), FICO, and debt service coverage (“DSC”) are based on weighted average for portfolio where data are available. LTV represents average LTV based on most recent appraisal against updated loan balance. Totals may not foot due to rounding. • Portfolio average loan size of $477,000 • 3Q23 average loan size of $591,000 • Portfolio average FICO of 762 and LTV of 63% • 3Q23 average FICO of 774 and LTV of 67% • Total delinquencies of 0.59% • Annualized net charge-off rate of 0.00% Non-owner Occupied CRE • Portfolio average loan size of $1.7 million • 3Q23 average loan size of $2.1 million • Portfolio average LTV of 51% and DSC of 1.88 • 3Q23 average LTV of 55% and DSC of 1.45 • Total delinquencies of 0.12% • Annualized net charge-off rate of 0.00% Commercial & Industrial • Portfolio average loan size of $701,000 • 3Q23 average loan size of $862,000 • Total delinquencies of 0.60% • Annualized net recovery rate of (0.02)% Multifamily • Portfolio average loan size of $2.3 million • 3Q23 average loan size of $929 thousand • Portfolio average LTV of 55% and DSC of 1.57 • 3Q23 average LTV of 57% and DSC of 1.32 • Total delinquencies of 0.00% • Annualized net charge-off rate of 0.00% Owner Occupied CRE • Portfolio average loan size of $992,000 • 3Q23 average loan size of $988,000 • Portfolio average LTV of 55% • 3Q23 average LTV of 68% • Total delinquencies of 0.51% • Annualized net charge-off rate of 0.00% Lease & Equipment Finance (FinPac) • Portfolio average loan & lease size of $41,000 • 3Q23 average loan & lease size of $66,000 • Portfolio average yield: ~10% • Total delinquencies of 4.21% • Annualized net charge-off rate of 5.15% Puget Sound, 19% WA Other, 8% Portland Metro, 13% OR Other, 14% Bay Area, 7% Northern CA, 9% Southern CA, 15% Other, 15% Mortgage, 17% FinPac, 5% C&I, 21% Owner Occupied CRE, 14% Non-OO CRE, 17% Multifamily, 15% Other Loan Categories, 11% Portfolio Composition at September 30, 2023 Geographic Distribution at September 30, 2023 Mortgage 20

CRE and C&I Portfolio Composition Agriculture, 9.0% Contractors, 7.6% Finance/Insurance, 7.8% Manufacturing, 7.4% Professional, 4.6% Public Admin, 6.9% Rental & Leasing, 7.4% Retail, 2.5% Support Services, 3.8% Transportation/ Warehousing, 9.0% Wholesale, 6.3% Gaming, 5.7% Dentists, 7.7% Other Healthcare, 3.3% Other, 11.3% Office, 16.6% Multifamily, 33.1% Industrial, 15.5% Retail, 11.9% Special Purpose, 7.6% Hotel/Motel, 4.2% Other, 11.3% CRE Portfolio Composition (1) $17.4 Billion at September 30, 2023 C&I Portfolio Composition (1) $9.5 Billion at September 30, 2023 (1) CRE portfolio composition includes non-owner occupied term and owner occupied term balances as well as multifamily balances. C&I portfolio composition includes term, lines of credit & other, and leases & equipment finance balances. (2) Owner occupied and non-owner occupied disclosure relates to commercial real estate portfolio excluding multifamily loans. 45% Owner Occupied / 55% Non-Owner Occupied (2) Commercial Line Utilization was 34% at September 30, 2023 21

Office Portfolio Details Puget Sound, 22% WA Other, 5% Portland Metro, 12% OR Other, 15%Bay Area, 6% N. CA, 11% S. CA, 20% Other, 9% Office Portfolio Metrics at September 30, 2023 Average loan size $1.3 million Average LTV 56% DSC (non-owner occupied) 1.73x % with guaranty (by $ / by #) 84% / 83% Past due 30-89 days $0.8mm / 0.03% of office Nonaccrual $14.7mm / 0.49% of office Special mention $11mm / 0.37% of office Classified $53mm / 1.74% of office Number of Loans by Balance Geography 22 ■ Loans secured by office properties represented 8% of our total loan portfolio at September 30, 2023. ■ Our office portfolio is 40% owner- occupied, 57% non-owner-occupied, and 3% construction. Construction loans represent 43% of loans repricing in 2023. Excluding construction balances, only 13% of our office portfolio reprices through 2025. ■ Properties located in suburban markets secure the majority of our office portfolio as only 6% of non-owner occupied office loans are located in downtown core business districts. ■ The average loan size in our office portfolio is $1.3 million, delinquencies are at a de minimis level, and the majority of our loans contain a guaranty. ■ Dental and other healthcare loans comprise 15% of our office portfolio. 1,746 441 71 38 7 6 <$1mm $1-5mm $5-10mm $10-20mm $20-30mm >$30mm 2023, 7% 2024, 4% 2025, 4% 2026 & After, 17% Fixed Rate*, 68% Repricing Schedule *Loans with a swap component are displayed as a fixed rate loan if the swap maturity is equal to the maturity of the loan. If the swap matures prior to the loan, the loan is displayed as adjustable with the rate resetting at the time of the swap maturity. 2023, 1% 2024, 5% 2025, 6% 2026 & After, 88% Maturity Schedule , 19 8 9 6 7 1,698 2 3 40 5

Allowance for Credit Losses (“ACL”) Footnotes: 1. Total includes $19.8 million for Reserve for Unfunded Commitments. 2. Total includes $21.5 million for Reserve for Unfunded Commitments. Allowance for Credit Losses by Loan Segment ($ in thousands) 6/30/2023 Q3 2023 Net (Charge-offs) Recoveries Reserve Build (Release) 9/30/2023 % of Loans and Leases Outstanding Commercial $100,342 $444 $15,946 $116,732 1.50 % Lease & Equipment Finance $117,130 ($22,172) $21,585 $116,543 6.74 % CRE $128,954 $31 $2,723 $131,708 0.68 % Residential/Home Equity $68,959 ($50) ($4,552) $64,357 0.80 % Consumer $9,045 ($1,378) $1,035 $8,702 4.51 % Total $424,430 ¹ ($23,125) $36,737 $438,042 ² 1.18 % % of loans and leases outstanding 1.15 % 1.18 % Remaining Credit Discount on Loans $94,113 $86,415 Total ACL Including Credit Discount $518,543 ¹ $524,457 ² % of loans and leases outstanding 1.40 % 1.41 % 23 Current Expected Credit Losses (“CECL”) Details ■ Provision expense of $37 million includes $35 million related to loans and leases and $2 million related to unfunded commitments. ■ The quarter’s provision expense reflects portfolio mix changes and credit migration trends. ■ Key components of Moody’s August 2023 baseline economic forecast, which is used to estimate the ACL, include: ■ U.S. real GDP average annualized growth of 2.0% in 2023, 1.3% in 2024, 2.3% in 2025, and 2.8% in 2026. ■ U.S. unemployment rate average of 3.6% in 2023, 4.0% in 2024, 4.2% in 2025, and 4.2% in 2026. ■ The average federal funds rate is expected to be 5.0% in 2023, 5.1% in 2024, 4.2% in 2025, and 3.1% in 2026.

Credit Quality Pr ov is io n Ex pe ns e ($ in m ill io ns ) N on perform ing assets to total assets Provision Expense & Non-Performing Assets to Total Assets* $27.6 $32.9 $17.1 $16.0 $36.7 $88.4 0.16% 0.18% 0.14% 0.15% 0.20% Provision expense Initial Provision Non Performing Assets To Total Assets Q3 2022 Q4 2022 Q1 2023 Q2 2023 Q3 2023 $— $20.0 $40.0 $60.0 $80.0 $100.0 $120.0 —% 0.05% 0.10% 0.15% 0.20% 0.25% 0.30% 0.35% Cl as si fie d Lo an s / To ta l L oa ns Classified A ssets / RBC Classified Assets 0.74% 0.73% 1.21% 1.13% 1.28%7.9% 7.8% 15.0% 13.4% 14.8% Classified Loans to Total Loans Classified Assets to Risk-Based Capital Q3 2022 Q4 2022 Q1 2023 Q2 2023 Q3 2023 —% 0.20% 0.40% 0.60% 0.80% 1.00% 1.20% 1.40% 1.60% —% 2.0% 4.0% 6.0% 8.0% 10.0% 12.0% 14.0% 16.0% A xi s Ti tle Net Charge-offs to Average Loans and Leases (annualized) 0.02% 0.01% —% 0.03% 0.01% 1.36% 2.84% 3.89% 5.96% 5.15% 0.11% 0.19% 0.23% 0.30% 0.25% Umpqua Bank (ex FinPac) FinPac Columbia Banking System, Inc. Q3 2022 Q4 2022 Q1 2023 Q2 2023 Q3 2023 —% 1.00% 2.00% 3.00% 4.00% 5.00% 6.00% 24 ■ If the remaining credit discount on loans of $86 million at September 30, 2023 is added to the ACL of $438 million at September 30, 2023, the ACL would increase to 1.41% of loans from the reported 1.18% level. ■ The increase in classified asset ratios between December 31, 2022 and March 31, 2023 relates to the addition of the historical Columbia portfolio and related purchase accounting adjustments and their impact on risk-based capital. The metrics are not reflective of any notable change in classified assets. A CL ($ in m ill io ns ) A CL / Total Loans and Leases Allowance for Credit Losses $295 $315 $436 $424 $438 $107 $94 $86 1.16% 1.21% 1.18% ACL Credit Discount ACL to Total Loans and Leases ACL + Credit Discount to Total loans and Leases Q3 2022 Q4 2022 Q1 2023 Q2 2023 Q3 2023 $100 $200 $300 $400 $500 $600 $700 —% 0.20% 0.40% 0.60% 0.80% 1.00% 1.20% 1.40%$105.5 Footnotes: *Q1 2023 provision expense of $105.5 million includes an initial provision of $88.4 million related to historical Columbia non-PCD loans. 1.40% 1.15% 1.18% 1.41%1.46%

Our Diversified Commercial Bank Business Model with a Strong Retail Presence Supports our Granular, High-Quality Deposit Base (1) Excludes public and brokered deposit balances. This is a non-GAAP financial measure. (2) Includes Reich & Tang Demand Deposit Marketplace program deposits of $577 million. Broker / Other, 7% Commercial, 49% Consumer, 38% Public, 6% September 30, 2023 Average consumer account balance $19 thousand Average commercial account balance $109 thousand Average customer account balance (1) $35 thousand Insured Cash Sweep (“ICS”) deposits (2) $3.5 billion Deposits in Certificate of Deposit Account Registry Service (“CDARS”) deposits $510 million Uninsured deposits as a % of total deposits 32% Non-interest, 37% Demand, 17% Money Market, 25% Savings, 7% Time, 14% Deposits by Type Deposits by Customer Segment 25 ■ Deposits were $42 billion at September 30, 2023 and represented by a largely granular base that is diversified by business line, industry, and geography. ■ Our deposit solutions, like ICS and CDARS, and our ability to collateralize select accounts, provide our customers with flexibility and improve the stability of our deposit base.

Capital Management 26 7.4% 9.4% 9.4% 11.5% 6.0% 7.0% 8.5% 10.5% 1.4% 2.4% 0.9% 1.0% Capital Threshold ¹ Capital Above Threshold ² Tier 1 Leverage CET1 Tier 1 Risk-Based Total Risk-Based —% 2.0% 4.0% 6.0% 8.0% 10.0% 12.0% ■ Declared a quarterly cash dividend of $0.36 per common share on August 14, 2023, which was paid September 11, 2023. ■ We expect the quarterly net impact of purchase accounting to be highly accretive to earnings, as detailed on slides 14 and 19 of this presentation. This outlook supports our view that capital is likely to build rapidly. ■ We expect to quickly approach and exceed our long-term total risk-based capital target of 12%, providing for enhanced flexibility to return excess capital to shareholders while continuing to support our expanding franchise. We are already above our long-term CET1 capital target of 9%. Note: Regulatory capital ratios are estimates pending completion and filing of Columbia’s regulatory reports. (1) Capital Threshold is the greater of Regulatory Well-Capitalized Threshold or Capital Adequacy Threshold + Capital Conservation Buffer. (2) Capital Above Threshold is the level of capital above Columbia’s Regulatory Minimum, which is equivalent to the Capital Threshold.

APPENDIX Income Statement Component Details Comparisons and Other Non-GAAP Reconciliation

Income Statement Component Details: GAAP Income For the Quarter Ended ($ in thousands, except per-share data) Q3 2023 Q2 2023 Q1 2023 Q4 2022 Q3 2022 Interest income $696,013 $675,729 $475,951 $352,247 $303,528 Interest expense 215,138 191,754 101,253 46,768 15,924 Net interest income 480,875 483,975 374,698 305,479 287,604 Provision for credit losses 36,737 16,014 105,539 32,948 27,572 Net interest income after provision 444,138 467,961 269,159 272,531 260,032 Non-interest income 43,981 39,678 54,735 34,879 29,445 Non-interest expense 304,147 328,559 342,818 194,982 177,964 Income before provision for income taxes 183,972 179,080 (18,924) 112,428 111,513 Provision for income taxes 48,127 45,703 (4,886) 29,464 27,473 Net income $135,845 $133,377 ($14,038) $82,964 $84,040 Revenue $524,856 $523,653 $429,433 $340,358 $317,049 Pre-provision net revenue (1) $220,709 $195,094 $86,615 $145,376 $139,085 Net interest margin (2) 3.91 % 3.93 % 4.08 % 4.01 % 3.88 % Efficiency ratio (2) 57.82 % 62.60 % 79.71 % 57.24 % 56.07 % PPNR return on assets (1) 1.65 % 1.46 % 0.89 % 1.82 % 1.80 % Return on assets 1.02 % 1.00 % (0.14) % 1.04 % 1.09 % Return on equity 11.07 % 10.84 % (1.70) % 13.50 % 12.99 % Return on tangible common equity (1) 16.93 % 16.63 % (2.09) % 13.53 % 13.02 % Earnings per share, diluted (3) $0.65 $0.64 ($0.09) $0.64 $0.65 28 Footnotes: (1) Non-GAAP financial measure. A reconciliation to the comparable GAAP measurement is provided at the end of this slide presentation. (2) Tax exempt interest has been adjusted to a taxable equivalent basis using a 21% tax rate and is included in the calculation of this ratio. (3) Periods prior to February 28, 2023, have been restated as a result of the adjustment to common shares outstanding based on the exchange ratio from the UHC merger of 0.5958. Notable Items ■ Q1 2023 results include only one month of the combined company’s operations and a related initial provision of $88 million. ■ Non-interest expense includes significant merger-related expense throughout the periods presented. These expenses are detailed on slide 34.

Income Statement Component Details: Impact of Non-Operating Items For the Quarter Ended ($ in thousands, except per-share data) Q3 2023 Q2 2023 Q1 2023 Q4 2022 Q3 2022 Interest income $— $— $— $— $— Interest expense — — — — — Net interest income — — — — — Provision for credit losses — — — — — Net interest income after provision — — — — — Non-interest income (15,023) (16,252) 8,074 (8,115) (22,575) Non-interest expense 22,955 31,768 117,189 13,603 2,133 Income before provision for income taxes (37,978) (48,020) (109,115) (21,718) (24,708) Provision for income taxes (9,482) (11,981) (23,565) (5,459) (6,116) Net income ($28,496) ($36,039) ($85,550) ($16,259) ($18,592) Revenue ($15,023) ($16,252) $8,074 ($8,115) ($22,575) Pre-provision net revenue ($37,978) ($48,020) ($109,115) ($21,718) ($24,708) Net interest margin NA NA NA NA NA Efficiency ratio 5.85 % 7.75 % 26.25 % 5.23 % 4.35 % PPNR return on assets (0.29) % (0.36) % (1.12) % (0.28) % (0.32) % Return on assets (0.21) % (0.27) % (0.88) % (0.20) % (0.24) % Return on equity (2.33) % (2.93) % (10.36) % (2.64) % (2.87) % Return on tangible common equity (3.55) % (4.50) % (12.73) % (2.65) % (2.88) % Earnings per share, diluted (1) ($0.14) ($0.17) ($0.55) ($0.12) ($0.14) 29 Notable Items ■ This table represents items that are excluded from GAAP to calculate operating metrics. They reconcile operating income and ratios on slide 30 to GAAP income and ratios on slide 28. All non-GAAP financial measures should be reviewed alongside GAAP financial measures detailed on slide 28. ■ Non-operating items in this table include gains and losses due to fair value changes and hedging activity as well as merger-related expense and exit and disposal charges. These items are detailed on slide 34. Footnotes: (1) Periods prior to February 28, 2023, have been restated as a result of the adjustment to common shares outstanding based on the exchange ratio from the UHC merger of 0.5958.

Income Statement Component Details: Operating Income (Non-GAAP) For the Quarter Ended ($ in thousands, except per-share data) Q3 2023 Q2 2023 Q1 2023 Q4 2022 Q3 2022 Interest income $696,013 $675,729 $475,951 $352,247 $303,528 Interest expense 215,138 191,754 101,253 46,768 15,924 Net interest income 480,875 483,975 374,698 305,479 287,604 Provision for credit losses 36,737 16,014 105,539 32,948 27,572 Net interest income after provision 444,138 467,961 269,159 272,531 260,032 Non-interest income 59,004 55,930 46,661 42,994 52,020 Non-interest expense 281,192 296,791 225,629 181,379 175,831 Income before provision for income taxes 221,950 227,100 90,191 134,146 136,221 Provision for income taxes 57,609 — 57,684 — 18,679 — 34,923 — 33,589 Net income $164,341 $169,416 $71,512 $99,223 $102,632 Revenue $539,879 $539,905 $421,359 $348,473 $339,624 Pre-provision net revenue $258,687 $243,114 $195,730 $167,094 $163,793 Net interest margin (1) 3.91 % 3.93 % 4.08 % 4.01 % 3.88 % Efficiency ratio (1) 51.97 % 54.85 % 53.46 % 52.01 % 51.72 % PPNR return on assets 1.94 % 1.82 % 2.01 % 2.10 % 2.12 % Return on assets 1.23 % 1.27 % 0.74 % 1.24 % 1.33 % Return on equity 13.40 % 13.77 % 8.66 % 16.14 % 15.86 % Return on tangible common equity 20.48 % 21.13 % 10.64 % 16.18 % 15.90 % Earnings per share, diluted (2) $0.79 $0.81 $0.46 $0.76 $0.79 30 Footnotes: (1) Tax exempt interest has been adjusted to a taxable equivalent basis using a 21% tax rate and is included in the calculation of this ratio. (2) Periods prior to February 28, 2023, have been restated as a result of the adjustment to common shares outstanding based on the exchange ratio from the UHC merger of 0.5958. Notable Items ■ The components of this table represent non-GAAP financial measures, and they should be reviewed alongside the GAAP financial measures on slide 28. Operating income components and ratios reconcile to GAAP income components and ratios by adding back the components detailed on slide 29.

Income Statement Component Details: Impact of Merger-Related Items For the Quarter Ended ($ in thousands, except per-share data) Q3 2023 Q2 2023 Q1 2023 Q4 2022 Q3 2022 Interest income $76,840 $74,723 $31,895 $387 $789 Interest expense (430) (337) (150) (57) (57) Net interest income 77,270 75,060 32,045 444 846 Provision for credit losses — — 88,427 — — Net interest income after provision 77,270 75,060 (56,382) 444 846 Non-interest income — — — — — Non-interest expense 29,879 35,553 12,660 1,019 1,025 Income before provision for income taxes 47,391 39,507 (69,042) (575) (179) Provision for income taxes 11,848 9,877 (17,261) (144) (45) Net income $35,543 $29,630 ($51,781) ($431) ($134) Revenue $77,270 $75,060 $32,045 $444 $846 Pre-provision net revenue $47,391 $39,507 $19,385 ($575) ($179) Net interest margin 0.63 % 0.61 % 0.35 % — % 0.01 % Efficiency ratio (2.22) % (1.21) % (1.15) % 0.23 % 0.17 % PPNR return on assets 0.36 % 0.29 % 0.20 % — % — % Return on assets 0.27 % 0.22 % (0.53) % (0.01) % — % Return on equity 2.90 % 2.41 % (6.27) % (0.07) % (0.02) % Return on tangible common equity 4.43 % 3.70 % (7.70) % (0.07) % (0.02) % Earnings per share, diluted (1) $0.17 $0.14 ($0.33) ($0.01) $— 31 Notable Items ■ This table represents merger-related items that are excluded from operating income components to calculate adjusted operating income components. They reconcile adjusted operating income and ratios on slide 32 to operating income and ratios on slide 30. All non-GAAP financial measures should be reviewed alongside GAAP financial measures detailed on slide 28. ■ Merger-related items include purchase accounting accretion and amortization (“PAA”) captured in interest income and interest expense and CDI amortization captured in non-interest expense. PAA items are detailed on slide 33. ■ Merger-related items in 2022 reflect PAA and CDI amortization related to UHC’s 2014 acquisition of Sterling Financial Corporation. Footnotes: (1) Periods prior to February 28, 2023, have been restated as a result of the adjustment to common shares outstanding based on the exchange ratio from the UHC merger of 0.5958.

Income Statement Component Details: Adjusted Operating Income (Non-GAAP) For the Quarter Ended ($ in thousands, except per-share data) Q3 2023 Q2 2023 Q1 2023 Q4 2022 Q3 2022 Interest income $619,173 $601,006 $444,056 $351,860 $302,739 Interest expense 215,568 192,091 101,403 46,825 15,981 Net interest income 403,605 408,915 342,653 305,035 286,758 Provision for credit losses 36,737 16,014 17,112 32,948 27,572 Net interest income after provision 366,868 392,901 325,541 272,087 259,186 Non-interest income 59,004 55,930 46,661 42,994 52,020 Non-interest expense 251,313 261,238 212,969 180,360 174,806 Income before provision for income taxes 174,559 187,593 159,233 134,721 136,400 Provision for income taxes 45,761 47,807 35,940 35,067 33,634 Net income $128,798 $139,786 $123,293 $99,654 $102,766 Revenue $462,609 $464,845 $389,314 $348,029 $338,778 Pre-provision net revenue $211,296 $203,607 $176,345 $167,669 $163,972 Net interest margin (1) 3.28 % 3.32 % 3.73 % 4.01 % 3.87 % Efficiency ratio (1) 54.19 % 56.06 % 54.61 % 51.78 % 51.55 % PPNR return on assets 1.58 % 1.53 % 1.81 % 2.10 % 2.12 % Return on assets 0.96 % 1.05 % 1.27 % 1.25 % 1.33 % Return on equity 10.50 % 11.36 % 14.93 % 16.21 % 15.88 % Return on tangible common equity 16.05 % 17.43 % 18.34 % 16.25 % 15.92 % Earnings per share, diluted (2) $0.62 $0.67 $0.79 $0.77 $0.79 32 Notable Items ■ The components of this table represent non-GAAP financial measures, and they should be reviewed alongside the GAAP financial measures on slide 28. Adjusted operating income components and ratios reconcile to operating income components and ratios detailed on slide 30 by adding back the components detailed on slide 31. Footnotes: (1) Tax exempt interest has been adjusted to a taxable equivalent basis using a 21% tax rate and is included in the calculation of this ratio. (2) Periods prior to February 28, 2023, have been restated as a result of the adjustment to common shares outstanding based on the exchange ratio from the UHC merger of 0.5958.

Non-GAAP Reconciliation: Tangible Capital and Net Interest Income & Margin ($ in thousands, except per-share data) Sep 30, 2023 Jun 30, 2023 Mar 31, 2023 Dec 31, 2022 Sep 30, 2022 Total shareholders' equity a $4,632,162 $4,828,188 $4,884,723 $2,479,826 $2,417,514 Less: Goodwill 1,029,234 1,029,234 1,030,142 — — Less: Other intangible assets, net 636,883 666,762 702,315 4,745 5,764 Tangible common shareholders’ equity b 2,966,045 3,132,192 3,152,266 2,475,081 2,411,750 Total assets c $51,989,593 $53,592,096 $53,994,226 $31,848,639 $31,471,960 Less: Goodwill 1,029,234 1,029,234 1,030,142 — — Less: Other intangible assets, net 636,883 666,762 702,315 4,745 5,764 Tangible assets d $50,323,476 $51,896,100 $52,261,769 $31,843,894 $31,466,196 Common shares outstanding at period end (1) e 208,575 208,514 208,429 129,321 129,320 Total shareholders' equity to total assets ratio a / c 8.91 % 9.01 % 9.05 % 7.79 % 7.68 % Tangible common equity ratio b / d 5.89 % 6.04 % 6.03 % 7.77 % 7.66 % Book value per common share (1) a / e $22.21 $23.16 $23.44 $19.18 $18.69 Tangible book value per common share (1) b / e $14.22 $15.02 $15.12 $19.14 $18.65 Footnotes: (1) Prior periods have been restated as a result of the adjustment to common shares outstanding based on the exchange ratio from the UHC merger of 0.5958. (2) The cumulative fair value discount on historical Columbia loans was established as of February 28, 2023, and the allocation between the credit-related discount and the rate-related discount was established at that time. Our disclosure of credit-related and rate-related discount accretion is an estimate based on the relative allocation of these two items to the discount at closing. (3) Tax exempt interest has been adjusted to a taxable equivalent basis using a 21% tax rate. 33 For the Quarter Ended ($ in thousands) Q3 2023 Q2 2023 Q1 2023 Q4 2022 Q3 2022 Net interest income a $482,031 $485,168 $375,369 $305,762 $287,933 Less: Acquired loan accretion - credit related (2) b 6,370 7,100 3,806 — — Net Interest Income, excluding credit PAA (2) c 475,661 478,068 371,563 305,762 287,933 Less: Acquired loan, securities, and interest-bearing liabilities accretion - rate related (2) d 70,900 67,960 28,239 444 846 Adjusted net interest income e $404,761 $410,108 $343,324 $305,318 $287,087 Average interest-earning assets f $48,981,105 $49,442,518 $37,055,705 $30,305,129 $29,437,103 Net interest margin (3) a / f 3.91 % 3.93 % 4.08 % 4.01 % 3.88 % Less: Acquired loan accretion - credit related (2) b / f 0.05 % 0.06 % 0.04 % — % — % Net Interest margin, excluding credit PAA (2), (3) c / f 3.86 % 3.87 % 4.04 % 4.01 % 3.88 % Less: Acquired loan, securities, and interest-bearing liabilities accretion - rate related (2) d / f 0.58 % 0.55 % 0.31 % — % 0.01 % Adjusted net interest margin (3) e / f 3.28 % 3.32 % 3.73 % 4.01 % 3.87 %

Non-GAAP Reconciliation For the Quarter Ended ($ in thousands) Q3 2023 Q2 2023 Q1 2023 Q4 2022 Q3 2022 Net interest income c $ 480,875 $ 483,975 $ 374,698 $ 305,479 $ 287,604 Non-interest income (GAAP) d $ 43,981 $ 39,678 $ 54,735 $ 34,879 $ 29,445 Less: non-interest income adjustments a 15,023 16,252 (8,074) 8,115 22,575 Operating non-interest income (non-GAAP) e $ 59,004 $ 55,930 $ 46,661 $ 42,994 $ 52,020 Revenue (GAAP) f $ 524,856 $ 523,653 $ 429,433 $ 340,358 $ 317,049 Operating revenue (non-GAAP) g $ 539,879 $ 539,905 $ 421,359 $ 348,473 $ 339,624 Non-interest expense (GAAP) h $ 304,147 $ 328,559 $ 342,818 $ 194,982 $ 177,964 Less: non-interest expense adjustments b (22,955) (31,768) (117,189) (13,603) (2,133) Operating non-interest expense (non-GAAP) i $ 281,192 $ 296,791 $ 225,629 $ 181,379 $ 175,831 Net (loss) income (GAAP) j $ 135,845 $ 133,377 $ (14,038) $ 82,964 $ 84,040 (Benefit) provision for income taxes 48,127 45,703 (4,886) 29,464 27,473 (Loss) income before provision for income taxes 183,972 179,080 (18,924) 112,428 111,513 Provision for credit losses 36,737 16,014 105,539 32,948 27,572 Pre-provision net revenue (PPNR) (non-GAAP) k 220,709 195,094 86,615 145,376 139,085 Less: Non-interest income adjustments a 15,023 16,252 (8,074) 8,115 22,575 Add: Non-interest expense adjustments b 22,955 31,768 117,189 13,603 2,133 Operating PPNR (non-GAAP) l $ 258,687 $ 243,114 $ 195,730 $ 167,094 $ 163,793 Net income (GAAP) j $ 135,845 $ 133,377 $ (14,038) $ 82,964 $ 84,040 Less: Non-interest income adjustments a 15,023 16,252 (8,074) 8,115 22,575 Add: Non-interest expense adjustments b 22,955 31,768 117,189 13,603 2,133 Tax effect of adjustments (9,482) (11,981) (23,565) (5,459) (6,116) Operating net income (non-GAAP) m $ 164,341 $ 169,416 $ 71,512 $ 99,223 $ 102,632 For the Quarter Ended ($ in thousands) Q3 2023 Q2 2023 Q1 2023 Q4 2022 Q3 2022 Non-Interest Income Adjustments Gain on sale of debt securities, net $ 4 $ — $ — $ — $ — Loss (gain) on equity securities, net (2,055) (697) 2,416 284 (2,647) Gain (loss) on swap derivatives 5,700 1,288 (3,543) (2,329) 4,194 Change in fair value of certain loans held for investment (19,247) (6,965) 9,488 4,192 (26,397) Change in fair value of MSR due to valuation inputs or assumptions 5,308 (2,242) (2,937) (9,914) 16,403 MSR hedge gain (loss) (4,733) (7,636) 2,650 (348) (14,128) Total non-interest income adjustments a $ (15,023) $ (16,252) $ 8,074 $ (8,115) $ (22,575) Non-Interest Expense Adjustments Merger related expense $ 18,938 $ 29,649 $ 115,898 $ 11,637 $ 769 Exit and disposal costs 4,017 2,119 1,291 1,966 1,364 Total non-interest expense adjustments b $ 22,955 $ 31,768 $ 117,189 $ 13,603 $ 2,133 34

Non-GAAP Reconciliation (cont.) For the Quarter Ended ($ in thousands, except per-share data) Q3 2023 Q2 2023 Q1 2023 Q4 2022 Q3 2022 Select Per-Share & Performance Metrics Earnings-per-share - basic (1) j/r $ 0.65 $ 0.64 $ (0.09) $ 0.64 $ 0.65 Earnings-per-share - diluted (1) j/s $ 0.65 $ 0.64 $ (0.09) $ 0.64 $ 0.65 Efficiency ratio (2) h/f 57.82 % 62.60 % 79.71 % 57.24 % 56.07 % Return on average assets j/n 1.02 % 1.00 % (0.14) % 1.04 % 1.09 % Return on average tangible assets j/o 1.05 % 1.03 % (0.15) % 1.04 % 1.09 % PPNR return on average assets k/n 1.65 % 1.46 % 0.89 % 1.82 % 1.80 % Return on average common equity j/p 11.07 % 10.84 % (1.70) % 13.50 % 12.99 % Return on average tangible common equity j/q 16.93 % 16.63 % (2.09) % 13.53 % 13.02 % Operating Per-Share & Performance Metrics Operating earnings-per-share - basic (1) m/r $ 0.79 $ 0.81 $ 0.46 $ 0.77 $ 0.79 Operating earnings-per-share - diluted (1) m/s $ 0.79 $ 0.81 $ 0.46 $ 0.76 $ 0.79 Operating efficiency ratio (2) i/g 51.97 % 54.85 % 53.46 % 52.01 % 51.72 % Operating return on average assets m/n 1.23 % 1.27 % 0.74 % 1.24 % 1.33 % Operating return on average tangible assets m/o 1.27 % 1.31 % 0.75 % 1.24 % 1.33 % Operating PPNR return on average assets l/n 1.94 % 1.82 % 2.01 % 2.10 % 2.12 % Operating return on average common equity m/p 13.40 % 13.77 % 8.66 % 16.14 % 15.86 % Operating return on average tangible common equity m/q 20.48 % 21.13 % 10.64 % 16.18 % 15.90 % For the Quarter Ended ($ in thousands) Q3 2023 Q2 2023 Q1 2023 Q4 2022 Q3 2022 Average Assets n $ 53,011,361 $ 53,540,574 $ 39,425,975 $ 31,637,490 $ 30,668,177 Less: Average goodwill and other intangible assets, net 1,684,093 1,718,705 623,042 5,298 6,343 Average tangible assets o $ 51,327,268 $ 51,821,869 $ 38,802,933 $ 31,632,192 $ 30,661,834 Average common shareholders’ equity p $ 4,866,975 $ 4,935,239 $ 3,349,761 $ 2,438,639 $ 2,567,266 Less: Average goodwill and other intangible assets, net 1,684,093 1,718,705 623,042 5,298 6,343 Average tangible common equity q $ 3,182,882 $ 3,216,534 $ 2,726,719 $ 2,433,341 $ 2,560,923 Weighted average basic shares outstanding (1) r 208,070 207,977 156,383 129,321 129,319 Weighted average diluted shares outstanding (1) s 208,645 208,545 156,383 129,801 129,733 Footnotes: (1) Prior periods have been restated as a result of the adjustment to common shares outstanding based on the exchange ratio from the UHC merger of 0.5958. (2) Tax exempt interest has been adjusted to a taxable equivalent basis using a 21% tax rate and added to stated revenue for this calculation. 35

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XML

Cover	Oct. 18, 2023
Cover [Abstract]
Document Type	8-K
Document Period End Date	Oct. 18, 2023
Entity Registrant Name	Columbia Banking System, Inc.
Entity Incorporation, State or Country Code	WA
Entity File Number	000-20288
Entity Tax Identification Number	91-1422237
Entity Address, Address Line One	1301 A Street
Entity Address, City or Town	Tacoma
Entity Address, State or Province	WA
Entity Address, Postal Zip Code	98402-2156
City Area Code	253
Local Phone Number	305-1900
Written Communications	false
Soliciting Material	false
Pre-commencement Tender Offer	false
Pre-commencement Issuer Tender Offer	false
Title of 12(g) Security	Common Stock, No Par Value
Trading Symbol	COLB
Security Exchange Name	NASDAQ
Entity Emerging Growth Company	false
Entity Central Index Key	0000887343
Amendment Flag	false