Director William G. Kistner's Purchase of Byline Bancorp Common Stock

This Form 4 filing reports that William G. Kistner, a director of Byline Bancorp, Inc., purchased 100 shares of the company's common stock on May 4, 2026, at a price of $31.97 per share. The transaction was coded as a purchase (P) and acquisition (A). Following this transaction, Kistner directly owns 1,036 shares and indirectly owns 14,189 shares through the William G. Kistner Trust dated June 22, 1973. The filing was signed by Thomas J. Bell III as attorney-in-fact on May 4, 2026. This represents an insider transaction by a company director, which is typically monitored by investors as it may signal confidence in the company's prospects.