Form 4 Filing by Patrick V.J.J. Vink for Spero Therapeutics, Inc.

This Form 4 filing details transactions by Patrick V.J.J. Vink, a director at Spero Therapeutics, Inc. On June 23, 2026, Mr. Vink acquired 10,000 shares of Common Stock through restricted stock units (RSUs) that vest on June 23, 2027. Additionally, he was granted a stock option, representing the right to buy 20,000 shares of Common Stock at an exercise price of $2.15 per share. This option vests in full on June 23, 2027. Following these transactions, Mr. Vink directly owns 85,000 shares of Common Stock and holds options for an additional 20,000 shares.