Proto Labs Inc

On August 15, 2025, Michael R. Kenison, Chief Operations Officer of the Company, entered into a 10b5-1 sales plan intended to satisfy the affirmative defense of Rule 10b5-1(c) under the Exchange Act. This 10b5-1 sales plan provides for (1) the sale of up to 10,681 shares of common stock related to the exercise of option awards granted to Mr. Kenison and (2) the sale of up to 7,500 shares of common stock related to vested restricted stock units granted to Mr. Kenison. This 10b5-1 sales plan will become effective on November 14, 2025 and will expire on June 12, 2026, or earlier completion of all authorized transactions under the plan.

On September 8, 2025, Oleg Ryaboy, Chief Technology Officer of the Company until October 3, 2025, entered into a 10b5-1 sales plan intended to satisfy the affirmative defense of Rule 10b5-1(c) under the Exchange Act. This 10b5-1 sales plan provides for (1) the sale of up to 3,048 shares of common stock related to the exercise of option awards granted to Mr. Ryaboy, (2) the sale of up to 4,200 shares of common stock related to vested restricted stock units granted to Mr. Ryaboy and (3) the sale of shares of common stock related to the future vesting of up to 5,658 restricted stock units held by Mr. Ryaboy. The exact number of shares of common stock that will be sold under this 10b5-1 sales plan related to vesting of restricted stock units is not yet determinable because an unknown number of shares will be sold to satisfy tax withholding obligations in connection with the vesting of the restricted stock units covered by the plan. This 10b5-1 sales plan will become effective on December 8, 2025 and will expire on August 15, 2026, or earlier completion of all authorized transactions under the plan.

During the three months ended September 30, 2025, no other directors or officers (as defined in Rule 16a-1(f) of the Exchange Act)adopted, modified orterminated any contract, instruction or written plan for the purchase or sale of our securities that was intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) of the Exchange Act or any non-Rule 10b5-1 trading arrangement (as defined in Item 408(c) of Regulation S-K).