EXHIBIT 99.1 COLUMBIA BANKING SYSTEM, INC. REPORTS THIRD QUARTER 2025 RESULTS $96 million$204 million $0.40$0.85 Net income Operating net income Earnings per common share - diluted Operating earnings per common share - diluted 1 1 CEO Commentary "Our third quarter performance reflects meaningful progress and growing momentum," said Clint Stein, President and CEO. "We closed our strategic acquisition of Pacific Premier, which completes our Western footprint and enhances our ability to generate top-quartile ...