EXHIBIT 99.1 COLUMBIA BANKING SYSTEM, INC. REPORTS SECOND QUARTER 2025 RESULTS $152 million$160 million $0.73$0.76 Net income Operating net income Earnings per common share - diluted Operating earnings per common share - diluted 1 1 CEO Commentary Investor Contact Jacquelynne "Jacque" Bohlen, SVP/Investor Relations Director, 503-727-4100, jacquebohlen@columbiabank.com "Our second quarter results demonstrate our focus on profitability and balance sheet optimization," said Clint Stein, President and CEO. "C ...