Form 4 Filing for FIRST BUSINESS FINANCIAL SERVICES, INC.

Brian D. Spielmann, CFO of FIRST BUSINESS FINANCIAL SERVICES, INC. (FBIZ), reported a net acquisition of 1689 shares of common stock on April 10, 2026. This transaction included the acquisition of 3190 shares under performance-based restricted stock unit awards (vesting for the 2023-2025 period) with no cost, and the disposal of 1501 shares at a price of $58.60 per share. Following these transactions, Mr. Spielmann directly owns 7311 shares of the company's common stock. The filing was signed by Peter J. Wilder under power of attorney on April 14, 2026.