COLUMBIA BANKING SYSTEM, INC. REPORTS THIRD QUARTER 2025 RESULTS

Acquisition and Branding Update
Columbia Banking System, Inc. ("Columbia," the "Company," "we," or "our") closed its acquisition of Pacific Premier Bancorp, Inc. ("Pacific Premier") on August 31, 2025, elevating Columbia's deposit market share to a top-10 position in Southern California. The acquisition completes our Western footprint and strengthens our presence as a leading financial institution in the western United States. Our integration efforts are progressing smoothly, and we remain on track to integrate systems in the first quarter of 2026.

Columbia Bank began serving customers under its unified name and brand effective September 1, 2025. The strategic transition streamlines our identity across all business lines, including Columbia Wealth Advisors, Columbia Trust Company, Columbia Private Bank, and Columbia Private Trust, making it easier for customers to recognize and engage with the full breadth of our services.

Share Repurchase Authorization Announcement
Columbia's Board of Directors has authorized the repurchase of up to $700 million of common stock under a new repurchase plan. COLB common share repurchases may be executed in the open market or through privately negotiated transactions, including under Rule 10b5-1 plans. The timing and exact amount of common share repurchases will be at the discretion of senior management and subject to various factors, including, without limitation, Columbia's capital position, financial performance, market conditions, and regulatory considerations. The repurchase program does not obligate Columbia to purchase any particular number of shares. The authorization will expire on November 30, 2026, but may be suspended, terminated or modified by the Board at any time.

"Our excess capital position as of September 30, 2025 supports the return of additional capital to our shareholders through share repurchases," commented Mr. Stein. "In addition, we expect to produce exceptional profitability, which will result in meaningful capital generation over the coming quarters. Even as we expand our capital return platform, we are continuing to drive organic growth as we optimize the balance sheet, in line with our commitment to enhancing long-term shareholder value."

Net Interest Income
Net interest income was $505 million for the third quarter of 2025, up $59 million from the prior quarter. The increase largely reflects the impact of one month operating as a combined company in the current period. Lower interest expense due to a favorable shift in Columbia's funding mix also contributed to the increase.

Columbia's net interest margin was 3.84% for the third quarter of 2025, up 9 basis points from the second quarter of 2025. Net interest margin benefited from lower funding costs, due to an increase in customer deposits and corresponding reduction in higher-cost funding sources. The net interest margin was also impacted by one month operating as a combined company in the current period.

The cost of interest-bearing deposits decreased 9 basis points from the prior quarter to 2.43% for the third quarter of 2025, compared to 2.29% for the month of September and 2.20% as of September 30, 2025, reflecting our proactive management of deposit rates ahead of and following the 25-basis point reduction in the federal funds rate in mid-September and a reduction in higher-cost brokered deposits during the month. The cost of interest-bearing deposits in September also benefited from the amortization of a premium related to Pacific Premier's time deposits, which will continue through December 31, 2025 at an equivalent monthly amount. The amortization contributed $4 million to net interest income during September, and favorably impacted deposit rates. Excluding this impact, the cost of interest-bearing deposits was 2.41% for the month of September and 2.32% as of September 30, 2025.

Columbia's cost of interest-bearing liabilities decreased 13 basis points from the prior quarter to 2.65% for the third quarter of 2025, compared to 2.47% for the month of September and 2.39% as of September 30, 2025. Excluding the previously discussed premium amortization, the cost of interest-bearing liabilities was 2.58% for the month of September and 2.50% as of September 30, 2025. We expect the premium to be fully amortized by December 31, 2025. Please refer to the Q3 2025 Earnings Presentation for additional net interest margin change details and interest rate sensitivity information.

Non-interest Income
Non-interest income was $77 million for the third quarter of 2025, up $12 million from the prior quarter. The increase was driven by quarterly changes in fair value adjustments and mortgage servicing rights ("MSR") hedging activity, due to interest rate fluctuations during the quarter, collectively resulting in a net fair value gain of $5 million in the third quarter compared to a net fair value loss of $1 million in the second quarter, as detailed in our non-GAAP disclosures. Excluding these items, non-interest income was up $6 million² between periods, due to one month operating as a combined company.

Non-interest Expense
Non-interest expense was $393 million for the third quarter of 2025, up $115 million from the prior quarter, due to higher merger expense and one month operating as a combined company. Excluding merger and restructuring expense and a $1 million reversal of prior FDIC assessment expense, non-interest expense was $307 million², up $37 million from the prior quarter, as Pacific Premier contributed $34 million to the quarter's run rate. Other miscellaneous expenses also trended higher as we reinvest prior cost savings into our franchise. Please refer to the Q3 2025 Earnings Presentation for additional expense details.

Balance Sheet
Total consolidated assets were $67.5 billion as of September 30, 2025, up from $51.9 billion as of June 30, 2025, due to the addition of Pacific Premier, partially offset by balance sheet optimization activity in the quarter. Cash and cash equivalents were $2.3 billion as of September 30, 2025, up from $1.9 billion as of June 30, 2025. Including secured off-balance sheet lines of credit, total available liquidity was $26.7 billion as of September 30, 2025, representing 40% of total assets, 48% of total deposits, and 130% of uninsured deposits. Available-for-sale securities, which are held on balance sheet at fair value, were $11.0 billion as of September 30, 2025, an increase of $2.4 billion relative to June 30, 2025, as securities acquired from Pacific Premier and an increase in the fair value of the portfolio was partially offset by net sales during the quarter. Please refer to the Q3 2025 Earnings Presentation for additional details related to our securities portfolio and liquidity position.

Gross loans and leases were $48.5 billion as of September 30, 2025, an increase of $10.8 billion relative to June 30, 2025, due to the addition of Pacific Premier, partially offset by run-off in commercial development and transactional loans, as well as the transfer of $282 million in residential real estate loans to the held-for-sale portfolio.  Excluding these factors, the loan portfolio was essentially unchanged between June 30, 2025 and September 30, 2025. "Our teams continue to focus on new client acquisition and relationship-building, contributing to the 19% increase in new loan originations for the current quarter compared to the prior quarter," commented Chris Merrywell, President of Columbia Bank. "We continue to prioritize balance sheet optimization and profitability, as we reduce our exposure to non-relationship loans." Please refer to the Q3 2025 Earnings Presentation for additional details related to our loan portfolio, which include underwriting characteristics, the composition of our commercial portfolios, and disclosure related to transactional loans.

Total deposits were $55.8 billion as of September 30, 2025, an increase of $14.0 billion relative to June 30, 2025, due to the addition of Pacific Premier and organic growth in customer deposits, partially offset by lower brokered deposits. "Customer deposit growth approached $800 million organically during the quarter, reflecting new customer activity and a seasonal lift in balances," stated Mr. Merrywell. "Our focus on relationship banking directly contributed to new deposit generation in the quarter, which reduced our reliance on wholesale funding sources." Brokered deposits and borrowings were $4.8 billion as of September 30, 2025, a decrease of $1.9 billion relative to June 30, 2025. Please refer to the Q3 2025 Earnings Presentation for additional details related to deposit characteristics and flows.

Credit Quality
The allowance for credit losses ("ACL") was $492 million, or 1.01% of loans and leases, as of September 30, 2025, compared to $439 million, or 1.17% as of June 30, 2025. The $53 million increase in the ACL includes the addition of $5 million related to Pacific Premier purchased credit deteriorated ("PCD") loans, which was booked at acquisition closing and did not affect the income statement. The provision for credit losses was $70 million for the third quarter of 2025 and includes an initial provision for acquired non-PCD loans and unfunded commitments and a recalibration of our models to incorporate historical Pacific Premier data into our ACL assumptions, where applicable. Excluding these items, our provision expense was $0 for the third quarter of 2025².

Net charge-offs were 0.22% of average loans and leases (annualized) for the third quarter of 2025, compared to 0.31% for the second quarter of 2025. Net charge-offs in the FinPac portfolio were $16 million in the third quarter, compared to $14 million in the second quarter. Net charge-offs excluding the FinPac portfolio were $6 million in the third quarter, compared to $15 million in the second quarter. Non-performing assets were $199 million, or 0.29% of total assets, as of September 30, 2025, compared to $180 million, or 0.35% of total assets, as of June 30, 2025. Please refer to the Q3 2025 Earnings Presentation for additional details related to the allowance for credit losses and other credit trends.

Capital
Columbia's book value per common share was $26.04 as of September 30, 2025, compared to $25.41 as of June 30, 2025. The increase reflects common shares issued and exchanged as a result of the acquisition, net capital generation from operations, and a favorable change in accumulated other comprehensive (loss) income ("AOCI") to $(268) million as of September 30, 2025, compared to $(333) million as of the prior quarter-end. The change in AOCI is due primarily to a decrease in the tax-effected net unrealized loss on available-for-sale securities to $240 million as of September 30, 2025, compared to $311 million as of June 30, 2025. Tangible book value per common share³ was $18.57 as of September 30, 2025, compared to $18.47 as of June 30, 2025. The items discussed above offset 1.7% tangible book value dilution as a result of the Pacific Premier acquisition, resulting in net tangible book value expansion during the quarter.

Columbia's estimated total risk-based capital ratio was 13.4% and its estimated common equity tier 1 risk-based capital ratio was 11.6% as of September 30, 2025, compared to 13.0% and 10.8%, respectively, as of June 30, 2025. Columbia remains above current "well-capitalized" regulatory minimums. The regulatory capital ratios as of September 30, 2025 are estimates, pending completion and filing of Columbia's regulatory reports. 

Earnings Presentation and Conference Call Information
Columbia's Q3 2025 Earnings Presentation provides additional disclosure. A copy will be available on our investor relations page: www.columbiabankingsystem.com.

Columbia will host its third quarter 2025 earnings conference call on October 30, 2025 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 2025 financial results. Participants may join the audiocast or register for the call using the link below to receive dial-in details and their own unique PINs. It is recommended you join 10 minutes prior to the start time.

Join the audiocast: https://edge.media-server.com/mmc/p/i6z93t5w/
Register for the call: https://register-conf.media-server.com/register/BIde1295f868b04a969240d44867cade1a
Access the replay through Columbia's investor relations page: https://www.columbiabankingsystem.com/news-market-data/event-calendar/default.aspx

About Columbia Banking System, Inc.
Columbia Banking System, Inc. (Nasdaq: COLB) is headquartered in Tacoma, Washington and is the parent company of Columbia Bank, an award-winning western U.S. regional bank. Columbia Bank is the largest bank headquartered in the Northwest and one of the largest banks headquartered in the West with locations in Arizona, California, Colorado, Idaho, Nevada, Oregon, Utah, and Washington. Columbia Bank combines the resources, sophistication, and expertise of a national bank with a commitment to deliver superior, personalized service. The bank 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. Columbia Bank customers also have access to comprehensive investment and wealth management expertise as well as healthcare and private banking through Columbia Wealth Management. 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. 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 and uncertainties 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 or renewed 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; risks related to our acquisition of Pacific Premier (the "Transaction"), including, among others, (i) diversion of management's attention from ongoing business operations and opportunities, (ii) cost savings and any revenue or expense synergies from the Transaction may not be fully realized or may take longer than anticipated to be realized, (iii) deposit attrition, customer or employee loss, and/or revenue loss as a result of the Transaction, and (iv) shareholder litigation that could negatively impact our business and operations; the impact of proposed or imposed tariffs by the U.S. government and retaliatory tariffs proposed or imposed by U.S. trading partners that could have an adverse impact on customers; our ability to effectively manage problem credits; the impact of bank failures or adverse developments at 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; potential adverse reactions or changes to business or employee relationships; 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.