X0609 4 2026-05-13 0001370450 Willdan Group, Inc. WLDN 0001270606 BIEBER MICHAEL A false 2401 EAST KATELLA AVENUE SUITE 300 ANAHEIM CA 92806 true true false false PRESIDENT AND CEO 0 Common Stock 2026-05-13 4 M 0 9991 16.27 A 259516 D Common Stock 2026-05-13 4 S 0 9991 92.65 D 249525 D Stock Options (Right to Buy) 16.27 2026-05-13 4 M 0 9991 0 D 2017-11-03 2026-11-03 Common Stock 50000 40009 D Includes (i) 18,000 shares of restricted stock units that vest in three substantially equal installments on each of March 3, 2027, March 3, 2028 and March 3, 2029, (ii) 12,834 shares of restricted stock units that vest in two substantially equal installments on each of March 17, 2027 and March 17, 2028, and (iii) 5,834 shares of restricted stock units that vest on March 20, 2027, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date. The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $92.50 to $92.85, inclusive. The Reporting Person undertakes to provide to Willdan Group, Inc., any security holder of Willdan Group, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote. Stock options granted under the Willdan Group, Inc. Amended and Restated 2008 Performance Incentive Plan, which vested in three equal installments on each of November 3, 2017, November 3, 2018, and November 3, 2019. /s/ Creighton K. Early, Attorney-in-fact for Michael A. Bieber 2026-05-14