WLDN

SEC source: 0001415889-25-007901 · form4-03122025_100336.xml · nonDerivative · entry 2

CHEN MICAH · CIK 0001733678 · EXECUTIVE VP & GENERAL COUNSEL

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 32,371

F3 · shares: Represents shares of the Issuer's Common Stock withheld to satisfy tax withholding obligations in connection with the vesting of the performance-based restricted stock units referenced in footnote (1).

F2 · balance_after: Includes (i) 4,200 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 934 shares of restricted stock that vest on March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001415889-25-007901 · form4-03122025_100336.xml · nonDerivative · entry 1

CHEN MICAH · CIK 0001733678 · EXECUTIVE VP & GENERAL COUNSEL

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 33,573

F1 · shares: Represents performance-based restricted stock units previously granted to the Reporting Person by the Issuer on March 7, 2023. The performance conditions applicable to the award were determined to have been satisfied by the Issuer's Compensation Committee effective on March 11, 2025, resulting in the immediate vesting of the restricted stock units as to 2,520 shares of Common Stock.

F2 · balance_after: Includes (i) 4,200 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 934 shares of restricted stock that vest on March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001415889-25-007897 · form4-03122025_100311.xml · nonDerivative · entry 1

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 422,454

F1 · shares: Represents performance-based restricted stock units previously granted to the Reporting Person by the Issuer on March 7, 2023. The performance conditions applicable to the award were determined to have been satisfied by the Issuer's Compensation Committee effective on March 11, 2025, resulting in the immediate vesting of the restricted stock units as to 15,750 shares of Common Stock.

F2 · balance_after: Includes (i) 2,248 shares of restricted stock that vest in two substantially equal installments on each of June 12, 2025 and June 12, 2026 and (ii) 5,834 shares of restricted stock that vest on March 7, 2026.

SEC source: 0001415889-25-007689 · form4-03112025_090331.xml · nonDerivative · entry 1

EARLY CREIGHTON K · CIK 0000904702 · EXECUTIVE VP AND CFO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 65,294

F1 · shares: Represents shares of the Issuer's Common Stock withheld to satisfy tax withholding obligations in connection with the vesting of restricted stock on March 7, 2025, which restricted stock was granted on March 7, 2023 and March 7, 2024.

F2 · balance_after: Includes 372 shares of Common Stock purchased under the Amended and Restated Willdan Group, Inc. 2006 Employee Stock Purchase Plan on December 31, 2024.

F3 · balance_after: Includes (i) 4,200 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 7,600 shares of restricted stock that vest on March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001415889-25-007691 · form4-03112025_090351.xml · nonDerivative · entry 1

BIEBER MICHAEL A · CIK 0001270606 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 171,579

F1 · shares: Represents shares of the Issuer's Common Stock withheld to satisfy tax withholding obligations in connection with the vesting of restricted stock on March 7, 2025, which restricted stock was granted on March 7, 2023.

F2 · balance_after: Includes 354 shares of Common Stock purchased under the Amended and Restated Willdan Group, Inc. 2006 Employee Stock Purchase Plan on December 31, 2024.

F3 · balance_after: Includes (i) 17,500 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 4,434 shares of restricted stock that vest on March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001415889-25-007686 · form4-03112025_090337.xml · nonDerivative · entry 1

CHEN MICAH · CIK 0001733678 · EXECUTIVE VP & GENERAL COUNSEL

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 31,053

F1 · shares: Represents shares of the Issuer's Common Stock withheld to satisfy tax withholding obligations in connection with the vesting of restricted stock on March 7, 2025, which restricted stock was granted on March 7, 2023.

F2 · balance_after: Includes 354 shares of Common Stock purchased under the Amended and Restated Willdan Group, Inc. 2006 Employee Stock Purchase Plan on December 31, 2024.

F3 · balance_after: Includes (i) 4,200 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 934 shares of restricted stock that vest on March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001415889-24-028867 · form4-12102024_101218.xml · derivative · entry 6

EARLY CREIGHTON K · CIK 0000904702 · EXECUTIVE VP AND CFO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,456

Underlying: Common Stock · 4,349 shares

Expires 2025-12-07

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · derivative.exercise_date: Stock options granted under the Willdan Group, Inc. Amended and Restated 2008 Performance Incentive Plan, which vested in three equal installments on each of December 7, 2016, December 7, 2017 and December 7, 2018.

SEC source: 0001415889-24-028867 · form4-12102024_101218.xml · nonDerivative · entry 4

EARLY CREIGHTON K · CIK 0000904702 · EXECUTIVE VP AND CFO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 69,146

F2 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $43.00 to $43.42, 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.

F1 · balance_after: Includes (i) 4,200 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 15,200 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001415889-24-028867 · form4-12102024_101218.xml · nonDerivative · entry 3

EARLY CREIGHTON K · CIK 0000904702 · EXECUTIVE VP AND CFO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 73,495

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · balance_after: Includes (i) 4,200 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 15,200 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001415889-24-028867 · form4-12102024_101218.xml · derivative · entry 5

EARLY CREIGHTON K · CIK 0000904702 · EXECUTIVE VP AND CFO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 5,805

Underlying: Common Stock · 234 shares

Expires 2025-12-07

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · derivative.exercise_date: Stock options granted under the Willdan Group, Inc. Amended and Restated 2008 Performance Incentive Plan, which vested in three equal installments on each of December 7, 2016, December 7, 2017 and December 7, 2018.

SEC source: 0001415889-24-028867 · form4-12102024_101218.xml · nonDerivative · entry 2

EARLY CREIGHTON K · CIK 0000904702 · EXECUTIVE VP AND CFO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 69,146

F1 · balance_after: Includes (i) 4,200 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 15,200 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001415889-24-028867 · form4-12102024_101218.xml · nonDerivative · entry 1

EARLY CREIGHTON K · CIK 0000904702 · EXECUTIVE VP AND CFO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 69,380

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · balance_after: Includes (i) 4,200 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 15,200 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001415889-24-029509 · form4-12162024_111210.xml · nonDerivative · entry 3

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 406,704

F1 · balance_after: Includes (i) 2,248 shares of restricted stock that vest in two substantially equal installments on each of June 12, 2025 and June 12, 2026, (ii) 11,667 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026 and (iii) 6,250 shares of restricted stock that vest on March 9, 2025.

SEC source: 0001415889-24-029509 · form4-12162024_111210.xml · nonDerivative · entry 2

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 414,404

F1 · balance_after: Includes (i) 2,248 shares of restricted stock that vest in two substantially equal installments on each of June 12, 2025 and June 12, 2026, (ii) 11,667 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026 and (iii) 6,250 shares of restricted stock that vest on March 9, 2025.

SEC source: 0001415889-24-029509 · form4-12162024_111210.xml · nonDerivative · entry 1

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 422,104

F1 · balance_after: Includes (i) 2,248 shares of restricted stock that vest in two substantially equal installments on each of June 12, 2025 and June 12, 2026, (ii) 11,667 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026 and (iii) 6,250 shares of restricted stock that vest on March 9, 2025.

SEC source: 0001415889-24-026632 · form4-11122024_101136.xml · derivative · entry 3

BIEBER MICHAEL A · CIK 0001270606 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 10,868 shares

Expires 2024-12-31

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · derivative.exercise_date: Stock options granted under the Willdan Group, Inc. Amended and Restated 2008 Performance Incentive Plan, which vested in three equal installments on each of December 31, 2015, December 31, 2016 and December 31, 2017.

SEC source: 0001415889-24-026632 · form4-11122024_101136.xml · nonDerivative · entry 2

BIEBER MICHAEL A · CIK 0001270606 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 173,654

F2 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $45.45 to $45.80, 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.

F1 · balance_after: Includes (i) 17,500 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 8,867 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001415889-24-026632 · form4-11122024_101136.xml · nonDerivative · entry 1

BIEBER MICHAEL A · CIK 0001270606 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 184,522

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · balance_after: Includes (i) 17,500 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 8,867 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001415889-24-026467 · form4-11082024_101111.xml · derivative · entry 3

BIEBER MICHAEL A · CIK 0001270606 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 10,868

Underlying: Common Stock · 1,804 shares

Expires 2024-12-31

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · derivative.exercise_date: Stock options granted under the Willdan Group, Inc. Amended and Restated 2008 Performance Incentive Plan, which vested in three equal installments on each of December 31, 2015, December 31, 2016 and December 31, 2017.

SEC source: 0001415889-24-026467 · form4-11082024_101111.xml · nonDerivative · entry 2

BIEBER MICHAEL A · CIK 0001270606 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 173,654

F2 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $45.77 to $45.93, 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.

F1 · balance_after: Includes (i) 17,500 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 8,867 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001415889-24-026467 · form4-11082024_101111.xml · nonDerivative · entry 1

BIEBER MICHAEL A · CIK 0001270606 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 175,458

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · balance_after: Includes (i) 17,500 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 8,867 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001415889-24-021845 · form4-08212024_090811.xml · nonDerivative · entry 2

EARLY CREIGHTON K · CIK 0000904702 · EXECUTIVE VP AND CFO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 69,146

F3 · shares: Represents shares of the Issuer's Common Stock withheld to satisfy tax withholding obligations in connection with the vesting of the performance-based restricted stock units referenced in footnote (1).

F2 · balance_after: Includes (i) 4,200 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 15,200 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001415889-24-021845 · form4-08212024_090811.xml · nonDerivative · entry 1

EARLY CREIGHTON K · CIK 0000904702 · EXECUTIVE VP AND CFO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 70,078

F1 · shares: Represents performance-based restricted stock units previously granted to the Reporting Person by the Issuer on August 2, 2022. The performance conditions applicable to the award were determined to have been satisfied by the Issuer's Compensation Committee on July 30, 2024, resulting in the immediate vesting of the restricted stock units as to 1,736 shares of Common Stock.

F2 · balance_after: Includes (i) 4,200 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 15,200 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001415889-24-021847 · form4-08212024_090804.xml · nonDerivative · entry 2

BIEBER MICHAEL A · CIK 0001270606 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 173,654

F3 · shares: Represents shares of the Issuer's Common Stock withheld to satisfy tax withholding obligations in connection with the vesting of the performance-based restricted stock units referenced in footnote (1).

F2 · balance_after: Includes (i) 17,500 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 8,867 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001415889-24-021847 · form4-08212024_090804.xml · nonDerivative · entry 1

BIEBER MICHAEL A · CIK 0001270606 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 177,972

F1 · shares: Represents performance-based restricted stock units previously granted to the Reporting Person by the Issuer on August 2, 2022. The performance conditions applicable to the award were determined to have been satisfied by the Issuer's Compensation Committee on July 30, 2024, resulting in the immediate vesting of the restricted stock units as to 8,246 shares of Common Stock.

F2 · balance_after: Includes (i) 17,500 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 8,867 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001415889-24-021840 · form4-08212024_090853.xml · nonDerivative · entry 2

CHEN MICAH · CIK 0001733678 · EXECUTIVE VP & GENERAL COUNSEL

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 31,157

F4 · shares: Represents shares of the Issuer's Common Stock withheld to satisfy tax withholding obligations in connection with the vesting of the performance-based restricted stock units referenced in footnote (1).

F2 · balance_after: Includes (i) 4,200 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 1,867 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

F3 · balance_after: Includes 683 shares of Common Stock purchased under the Amended and Restated Willdan Group, Inc. 2006 Employee Stock Purchase Plan on June 30, 2024.

SEC source: 0001415889-24-021840 · form4-08212024_090853.xml · nonDerivative · entry 1

CHEN MICAH · CIK 0001733678 · EXECUTIVE VP & GENERAL COUNSEL

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 31,917

F1 · shares: Represents performance-based restricted stock units previously granted to the Reporting Person by the Issuer on August 2, 2022. The performance conditions applicable to the award were determined to have been satisfied by the Issuer's Compensation Committee on July 30, 2024, resulting in the immediate vesting of the restricted stock units as to 1,736 shares of Common Stock.

F2 · balance_after: Includes (i) 4,200 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 1,867 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

F3 · balance_after: Includes 683 shares of Common Stock purchased under the Amended and Restated Willdan Group, Inc. 2006 Employee Stock Purchase Plan on June 30, 2024.

SEC source: 0001415889-24-021838 · form4-08212024_090816.xml · nonDerivative · entry 1

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 429,804

F1 · shares: Represents performance-based restricted stock units previously granted to the Reporting Person by the Issuer on August 2, 2022. The performance conditions applicable to the award were determined to have been satisfied by the Issuer's Compensation Committee on July 30, 2024, resulting in the immediate vesting of the restricted stock units as to 13,648 shares of Common Stock.

F2 · balance_after: Includes (i) 2,248 shares of restricted stock that vest in two substantially equal installments on each of June 12, 2025 and June 12, 2026, (ii) 11,667 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026 and (iii) 6,250 shares of restricted stock that vest on March 9, 2025.

SEC source: 0001415889-24-021319 · form4-08142024_100833.xml · derivative · entry 3

BIEBER MICHAEL A · CIK 0001270606 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 12,672

Underlying: Common Stock · 750 shares

Expires 2024-12-31

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · derivative.exercise_date: Stock options granted under the Willdan Group, Inc. Amended and Restated 2008 Performance Incentive Plan, which vested in three equal installments on each of December 31, 2015, December 31, 2016 and December 31, 2017.

SEC source: 0001415889-24-021319 · form4-08142024_100833.xml · nonDerivative · entry 2

BIEBER MICHAEL A · CIK 0001270606 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 169,726

F2 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $36.41 to $36.49, 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.

F1 · balance_after: Includes (i) 17,500 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 8,867 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001415889-24-021319 · form4-08142024_100833.xml · nonDerivative · entry 1

BIEBER MICHAEL A · CIK 0001270606 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 170,476

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · balance_after: Includes (i) 17,500 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 8,867 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001415889-24-021105 · form4-08122024_090804.xml · derivative · entry 6

BIEBER MICHAEL A · CIK 0001270606 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 13,422

Underlying: Common Stock · 9,209 shares

Expires 2024-12-31

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F4 · derivative.exercise_date: Stock options granted under the Willdan Group, Inc. Amended and Restated 2008 Performance Incentive Plan, which vested in three equal installments on each of December 31, 2015, December 31, 2016 and December 31, 2017.

SEC source: 0001415889-24-021105 · form4-08122024_090804.xml · nonDerivative · entry 4

BIEBER MICHAEL A · CIK 0001270606 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 169,726

F3 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $36.35 to $36.39, 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.

F1 · balance_after: Includes (i) 17,500 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 8,867 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001415889-24-021105 · form4-08122024_090804.xml · nonDerivative · entry 3

BIEBER MICHAEL A · CIK 0001270606 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 178,935

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · balance_after: Includes (i) 17,500 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 8,867 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001415889-24-021105 · form4-08122024_090804.xml · derivative · entry 5

BIEBER MICHAEL A · CIK 0001270606 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 22,631

Underlying: Common Stock · 10,273 shares

Expires 2024-12-31

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F4 · derivative.exercise_date: Stock options granted under the Willdan Group, Inc. Amended and Restated 2008 Performance Incentive Plan, which vested in three equal installments on each of December 31, 2015, December 31, 2016 and December 31, 2017.

SEC source: 0001415889-24-021105 · form4-08122024_090804.xml · nonDerivative · entry 2

BIEBER MICHAEL A · CIK 0001270606 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 169,726

F2 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $36.35 to $36.67, 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.

F1 · balance_after: Includes (i) 17,500 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 8,867 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001415889-24-021105 · form4-08122024_090804.xml · nonDerivative · entry 1

BIEBER MICHAEL A · CIK 0001270606 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 179,999

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · balance_after: Includes (i) 17,500 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 8,867 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001415889-24-020999 · form4-08082024_090849.xml · derivative · entry 4

EARLY CREIGHTON K · CIK 0000904702 · EXECUTIVE VP AND CFO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 6,039

Underlying: Common Stock · 10,000 shares

Expires 2025-12-07

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F5 · derivative.exercise_date: Stock options granted under the Willdan Group, Inc. Amended and Restated 2008 Performance Incentive Plan, which vested in three equal installments on each of December 7, 2016, December 7, 2017 and December 7, 2018.

SEC source: 0001415889-24-020999 · form4-08082024_090849.xml · nonDerivative · entry 3

EARLY CREIGHTON K · CIK 0000904702 · EXECUTIVE VP AND CFO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 68,342

F4 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $37.00 to $37.30, 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.

F1 · balance_after: Includes (i) 4,200 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 15,200 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

F2 · balance_after: Includes 659 shares of Common Stock purchased under the Amended and Restated Willdan Group, Inc. 2006 Employee Stock Purchase Plan on June 30, 2024.

SEC source: 0001415889-24-020999 · form4-08082024_090849.xml · nonDerivative · entry 2

EARLY CREIGHTON K · CIK 0000904702 · EXECUTIVE VP AND CFO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 68,538

F3 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $36.00 to $36.97, 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.

F1 · balance_after: Includes (i) 4,200 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 15,200 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

F2 · balance_after: Includes 659 shares of Common Stock purchased under the Amended and Restated Willdan Group, Inc. 2006 Employee Stock Purchase Plan on June 30, 2024.

SEC source: 0001415889-24-020999 · form4-08082024_090849.xml · nonDerivative · entry 1

EARLY CREIGHTON K · CIK 0000904702 · EXECUTIVE VP AND CFO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 78,342

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · balance_after: Includes (i) 4,200 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 15,200 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

F2 · balance_after: Includes 659 shares of Common Stock purchased under the Amended and Restated Willdan Group, Inc. 2006 Employee Stock Purchase Plan on June 30, 2024.

SEC source: 0001415889-24-020997 · form4-08082024_090803.xml · derivative · entry 6

BIEBER MICHAEL A · CIK 0001270606 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 32,904

Underlying: Common Stock · 10,346 shares

Expires 2024-12-31

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F5 · derivative.exercise_date: Stock options granted under the Willdan Group, Inc. Amended and Restated 2008 Performance Incentive Plan, which vested in three equal installments on each of December 31, 2015, December 31, 2016 and December 31, 2017.

SEC source: 0001415889-24-020997 · form4-08082024_090803.xml · nonDerivative · entry 4

BIEBER MICHAEL A · CIK 0001270606 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 169,726

F4 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $36.45 to $37.40, 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.

F1 · balance_after: Includes (i) 17,500 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 8,867 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

F2 · balance_after: Includes 683 shares of Common Stock purchased under the Amended and Restated Willdan Group, Inc. 2006 Employee Stock Purchase Plan on June 30, 2024.

SEC source: 0001415889-24-020997 · form4-08082024_090803.xml · nonDerivative · entry 3

BIEBER MICHAEL A · CIK 0001270606 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 180,072

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · balance_after: Includes (i) 17,500 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 8,867 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

F2 · balance_after: Includes 683 shares of Common Stock purchased under the Amended and Restated Willdan Group, Inc. 2006 Employee Stock Purchase Plan on June 30, 2024.

SEC source: 0001415889-24-020997 · form4-08082024_090803.xml · derivative · entry 5

BIEBER MICHAEL A · CIK 0001270606 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 43,250

Underlying: Common Stock · 12,000 shares

Expires 2024-12-31

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F5 · derivative.exercise_date: Stock options granted under the Willdan Group, Inc. Amended and Restated 2008 Performance Incentive Plan, which vested in three equal installments on each of December 31, 2015, December 31, 2016 and December 31, 2017.

SEC source: 0001415889-24-020997 · form4-08082024_090803.xml · nonDerivative · entry 2

BIEBER MICHAEL A · CIK 0001270606 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 169,726

F3 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $36.45 to $36.84, 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.

F1 · balance_after: Includes (i) 17,500 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 8,867 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

F2 · balance_after: Includes 683 shares of Common Stock purchased under the Amended and Restated Willdan Group, Inc. 2006 Employee Stock Purchase Plan on June 30, 2024.

SEC source: 0001415889-24-020997 · form4-08082024_090803.xml · nonDerivative · entry 1

BIEBER MICHAEL A · CIK 0001270606 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 181,726

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · balance_after: Includes (i) 17,500 shares of restricted stock units that vest in three substantially equal installments on each of March 20, 2025, March 20, 2026 and March 20, 2027 and (ii) 8,867 shares of restricted stock that vest in two substantially equal installments on each of March 7, 2025 and March 7, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

F2 · balance_after: Includes 683 shares of Common Stock purchased under the Amended and Restated Willdan Group, Inc. 2006 Employee Stock Purchase Plan on June 30, 2024.

SEC source: 0001654954-24-008824 · section16.xml · nonDerivative · entry 1

Forager Fund, L.P. · CIK 0001539281 · 10% owner

Kissel Edward Urban · CIK 0001877495 · 10% owner

MacArthur Robert Symmes · CIK 0001877496 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,255,765

F1 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $29.90 to $30.06 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within this range.

F2 · ownership.direct: The shares reported are directly held by Forager Fund, L.P. (the "Fund"). Each of Messrs. Kissel and MacArthur is a principal of Forager Capital Management, LLC, the general partner of the Fund (the "GP"), and has shared authority to vote (or direct the vote of), and to dispose (or direct the disposal) of, these shares on behalf of the GP. Each of the Reporting Persons disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein, if any.

SEC source: 0001654954-24-008109 · section16.xml · nonDerivative · entry 1

Forager Fund, L.P. · CIK 0001539281 · 10% owner

Kissel Edward Urban · CIK 0001877495 · 10% owner

MacArthur Robert Symmes · CIK 0001877496 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 144,995

F1 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $29.26 to $29.29 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within this range.

F2 · ownership.direct: The shares reported are directly held by Forager Fund, L.P. (the "Fund"). Each of Messrs. Kissel and MacArthur is a principal of Forager Capital Management, LLC, the general partner of the Fund (the "GP"), and has shared authority to vote (or direct the vote of), and to dispose (or direct the disposal) of, these shares on behalf of the GP. Each of the Reporting Persons disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein, if any.

SEC source: 0001654954-24-008174 · section16.xml · nonDerivative · entry 1

Forager Fund, L.P. · CIK 0001539281 · 10% owner

Kissel Edward Urban · CIK 0001877495 · 10% owner

MacArthur Robert Symmes · CIK 0001877496 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,443,995

F1 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $29.26 to $29.29 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within this range.

F2 · balance_after: The original Form 4, filed on June 24, 2024, is being amended by this Form 4 amendment to correct an error in the number of shares reported in Column 5.

F3 · ownership.direct: The shares reported are directly held by Forager Fund, L.P. (the "Fund"). Each of Messrs. Kissel and MacArthur is a principal of Forager Capital Management, LLC, the general partner of the Fund (the "GP"), and has shared authority to vote (or direct the vote of), and to dispose (or direct the disposal) of, these shares on behalf of the GP. Each of the Reporting Persons disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein, if any.