WLDN

SEC source: 0001270606-26-000006 · form4-03122026_090314.xml · nonDerivative · entry 1

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

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 242,692

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, 2026, resulting in the immediate vesting of the restricted stock units as to 18,810 shares of Common Stock.

F2 · balance_after: 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) 19,250 shares of restricted stock units that vest in three substantially equal installments on each of March 17, 2026, March 17, 2027 and March 17, 2028, and (iii) 11,667 shares of restricted stock units that vest in two substantially equal installments on each of March 20, 2026 and March 20, 2027, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001733678-26-000006 · form4-03122026_090319.xml · nonDerivative · entry 2

CHEN MICAH · CIK 0001733678 · EXECUTIVE VP & GENERAL COUNSEL

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 46,889

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) 4,500 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) 4,620 shares of restricted stock units that vest in three substantially equal installments on each of March 17, 2026, March 17, 2027 and March 17, 2028, and (iii) 2,800 shares of restricted stock units that vest in two substantially equal installments on each of March 20, 2026 and March 20, 2027, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001733678-26-000006 · form4-03122026_090319.xml · nonDerivative · entry 1

CHEN MICAH · CIK 0001733678 · EXECUTIVE VP & GENERAL COUNSEL

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 48,627

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, 2026, resulting in the immediate vesting of the restricted stock units as to 3,960 shares of Common Stock.

F2 · balance_after: Includes (i) 4,500 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) 4,620 shares of restricted stock units that vest in three substantially equal installments on each of March 17, 2026, March 17, 2027 and March 17, 2028, and (iii) 2,800 shares of restricted stock units that vest in two substantially equal installments on each of March 20, 2026 and March 20, 2027, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001395188-26-000002 · form4-03122026_090355.xml · nonDerivative · entry 1

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 95,446

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, 2026, resulting in the immediate vesting of the restricted stock units as to 24,750 shares of Common Stock.

F2 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026, and (ii) 1,124 shares of restricted stock that vest on June 12, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0000904702-26-000005 · form4-03112026_110301.xml · nonDerivative · entry 1

EARLY CREIGHTON K · CIK 0000904702 · EXECUTIVE VP AND CFO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 75,175

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, 2026, which restricted stock was granted on March 7, 2023.

F2 · balance_after: Includes (i) 5,625 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) 4,620 shares of restricted stock units that vest in three substantially equal installments on each of March 17, 2026, March 17, 2027 and March 17, 2028, and (iii) 2,800 shares of restricted stock units that vest in two substantially equal installments on each of March 20, 2026 and March 20, 2027, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001270606-26-000004 · form4-03112026_110353.xml · nonDerivative · entry 1

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

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 223,882

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, 2026, which restricted stock was granted on March 7, 2023.

F2 · balance_after: 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) 19,250 shares of restricted stock units that vest in three substantially equal installments on each of March 17, 2026, March 17, 2027 and March 17, 2028, and (iii) 11,667 shares of restricted stock units that vest in two substantially equal installments on each of March 20, 2026 and March 20, 2027, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001733678-26-000004 · form4-03112026_110338.xml · nonDerivative · entry 1

CHEN MICAH · CIK 0001733678 · EXECUTIVE VP & GENERAL COUNSEL

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 44,667

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, 2026, which restricted stock was granted on March 7, 2023.

F2 · balance_after: Includes (i) 4,500 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) 4,620 shares of restricted stock units that vest in three substantially equal installments on each of March 17, 2026, March 17, 2027 and March 17, 2028, and (iii) 2,800 shares of restricted stock units that vest in two substantially equal installments on each of March 20, 2026 and March 20, 2027, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001640413-26-000002 · form4-03102026_090348.xml · nonDerivative · entry 1

Cohen Steven A · CIK 0001640413 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 20,849

F1 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $81.80 to $81.94, 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.

F2 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026 and (ii) 1,124 shares of restricted stock that vest on June 12, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0000904702-26-000002 · form4-03052026_110321.xml · nonDerivative · entry 1

EARLY CREIGHTON K · CIK 0000904702 · EXECUTIVE VP AND CFO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 79,482

F1 · shares: Represents shares of restricted stock units awarded to the Reporting Person by the Issuer on March 3, 2026, which vest in three substantially equal installments on each of March 3, 2027, March 3, 2028 and March 3, 2029, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

F2 · balance_after: Includes (i) 5,625 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) 4,620 shares of restricted stock units that vest in three substantially equal installments on each of March 17, 2026, March 17, 2027 and March 17, 2028, (iii) 2,800 shares of restricted stock units that vest in two substantially equal installments on each of March 20, 2026 and March 20, 2027 and (iv) 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.

F3 · balance_after: Includes 176 shares of Common Stock purchased under the Amended and Restated Willdan Group, Inc. 2006 Employee Stock Purchase Plan on December 31, 2025.

SEC source: 0001270606-26-000002 · form4-03052026_100346.xml · nonDerivative · entry 1

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

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 225,696

F1 · shares: Represents shares of restricted stock units awarded to the Reporting Person by the Issuer on March 3, 2026, which vest in three substantially equal installments on each of March 3, 2027, March 3, 2028 and March 3, 2029, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

F2 · balance_after: 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) 19,250 shares of restricted stock units that vest in three substantially equal installments on each of March 17, 2026, March 17, 2027 and March 17, 2028, (iii) 11,667 shares of restricted stock units that vest in two substantially equal installments on each of March 20, 2026 and March 20, 2027 and (iv) 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.

F3 · balance_after: Includes 154 shares of Common Stock purchased under the Amended and Restated Willdan Group, Inc. 2006 Employee Stock Purchase Plan on December 31, 2025.

SEC source: 0001733678-26-000002 · form4-03052026_110356.xml · nonDerivative · entry 1

CHEN MICAH · CIK 0001733678 · EXECUTIVE VP & GENERAL COUNSEL

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 45,077

F1 · shares: Represents shares of restricted stock units awarded to the Reporting Person by the Issuer on March 3, 2026, which vest in three substantially equal installments on each of March 3, 2027, March 3, 2028 and March 3, 2029, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

F2 · balance_after: Includes (i) 4,500 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) 4,620 shares of restricted stock units that vest in three substantially equal installments on each of March 17, 2026, March 17, 2027 and March 17, 2028, (iii) 2,800 shares of restricted stock units that vest in two substantially equal installments on each of March 20, 2026 and March 20, 2027 and (iv) 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.

F3 · balance_after: Includes 154 shares of Common Stock purchased under the Amended and Restated Willdan Group, Inc. 2006 Employee Stock Purchase Plan on December 31, 2025.

SEC source: 0001733678-25-000006 · form4-09222025_090906.xml · derivative · entry 3

CHEN MICAH · CIK 0001733678 · EXECUTIVE VP & GENERAL COUNSEL

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 40,000

Underlying: Common Stock · 10,000 shares

Expires 2027-07-17

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.

F2 · 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 July 17, 2018, July 17, 2019, and July 17, 2020.

SEC source: 0001733678-25-000006 · form4-09222025_090906.xml · nonDerivative · entry 2

CHEN MICAH · CIK 0001733678 · EXECUTIVE VP & GENERAL COUNSEL

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 40,423

F1 · balance_after: Includes (i) 4,620 shares of restricted stock units that vest in three substantially equal installments on each of March 17, 2026, March 17, 2027 and March 17, 2028, (ii) 2,800 shares of restricted stock units that vest in two substantially equal installments on each of March 20, 2026 and March 20, 2027 and (iii) 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: 0001733678-25-000006 · form4-09222025_090906.xml · nonDerivative · entry 1

CHEN MICAH · CIK 0001733678 · EXECUTIVE VP & GENERAL COUNSEL

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 50,423

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) 4,620 shares of restricted stock units that vest in three substantially equal installments on each of March 17, 2026, March 17, 2027 and March 17, 2028, (ii) 2,800 shares of restricted stock units that vest in two substantially equal installments on each of March 20, 2026 and March 20, 2027 and (iii) 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: 0001701806-25-000005 · form4-09222025_090957.xml · nonDerivative · entry 1

McGinn Dennis V · CIK 0001701806 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 11,330

F1 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $106.00 to $106.87, inclusive. The Reporting Person undertakes 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 the ranges set forth in this footnote (1).

F2 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026 and (ii) 1,124 shares of restricted stock that vest on June 12, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001415889-25-023045 · form4-08262025_090821.xml · derivative · entry 3

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 89,736

Underlying: Common Stock · 5,182 shares

Expires 2026-11-03

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 November 3, 2017, November 3, 2018 and November 3, 2019.

SEC source: 0001415889-25-023045 · form4-08262025_090821.xml · nonDerivative · entry 2

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 70,696

F2 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $118.07 to $118.38, inclusive. The Reporting Person undertakes 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 the ranges set forth in this footnote (2).

F1 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026, (ii) 1,124 shares of restricted stock that vest on June 12, 2026, and (iii) 5,834 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: 0001415889-25-023045 · form4-08262025_090821.xml · nonDerivative · entry 1

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 75,878

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) 1,781 shares of restricted stock that vest on June 11, 2026, (ii) 1,124 shares of restricted stock that vest on June 12, 2026, and (iii) 5,834 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: 0001415889-25-023043 · form4-08262025_090801.xml · nonDerivative · entry 7

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 70,696

F8 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $110.18 to $111.16, inclusive.

F2 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026, (ii) 1,124 shares of restricted stock that vest on June 12, 2026, and (iii) 5,834 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: 0001415889-25-023043 · form4-08262025_090801.xml · nonDerivative · entry 6

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 98,188

F7 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $109.16 to $110.13, inclusive.

F2 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026, (ii) 1,124 shares of restricted stock that vest on June 12, 2026, and (iii) 5,834 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: 0001415889-25-023043 · form4-08262025_090801.xml · nonDerivative · entry 5

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 131,284

F6 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $108.16 to $109.15, inclusive.

F2 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026, (ii) 1,124 shares of restricted stock that vest on June 12, 2026, and (iii) 5,834 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: 0001415889-25-023043 · form4-08262025_090801.xml · nonDerivative · entry 4

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 156,272

F5 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $107.16 to $108.13, inclusive.

F2 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026, (ii) 1,124 shares of restricted stock that vest on June 12, 2026, and (iii) 5,834 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: 0001415889-25-023043 · form4-08262025_090801.xml · nonDerivative · entry 3

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 165,246

F4 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $106.12 to $107.04, inclusive.

F2 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026, (ii) 1,124 shares of restricted stock that vest on June 12, 2026, and (iii) 5,834 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: 0001415889-25-023043 · form4-08262025_090801.xml · nonDerivative · entry 2

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 172,766

F3 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $105.1 to $106.01, inclusive.

F2 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026, (ii) 1,124 shares of restricted stock that vest on June 12, 2026, and (iii) 5,834 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: 0001415889-25-023043 · form4-08262025_090801.xml · nonDerivative · entry 1

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 177,676

F1 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $104.06 to $105.01, inclusive. The Reporting Person undertakes 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 the ranges set forth in this footnote (1), footnote (3), footnote (4), footnote (5), footnote (6), footnote (7) and footnote (8).

F2 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026, (ii) 1,124 shares of restricted stock that vest on June 12, 2026, and (iii) 5,834 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: 0001415889-25-022939 · form4-08252025_090850.xml · nonDerivative · entry 6

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 188,291

F7 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at $106.34.

F2 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026, (ii) 1,124 shares of restricted stock that vest on June 12, 2026, and (iii) 5,834 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: 0001415889-25-022939 · form4-08252025_090850.xml · nonDerivative · entry 5

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 188,391

F6 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $105.34 to $106.28, inclusive.

F2 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026, (ii) 1,124 shares of restricted stock that vest on June 12, 2026, and (iii) 5,834 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: 0001415889-25-022939 · form4-08252025_090850.xml · nonDerivative · entry 4

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 221,771

F5 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $104.29 to $105.28, inclusive.

F2 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026, (ii) 1,124 shares of restricted stock that vest on June 12, 2026, and (iii) 5,834 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: 0001415889-25-022939 · form4-08252025_090850.xml · nonDerivative · entry 3

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 255,721

F4 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $103.29 to $104.28, inclusive.

F2 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026, (ii) 1,124 shares of restricted stock that vest on June 12, 2026, and (iii) 5,834 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: 0001415889-25-022939 · form4-08252025_090850.xml · nonDerivative · entry 2

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 289,185

F3 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $102.29 to $103.28, inclusive.

F2 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026, (ii) 1,124 shares of restricted stock that vest on June 12, 2026, and (iii) 5,834 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: 0001415889-25-022939 · form4-08252025_090850.xml · nonDerivative · entry 1

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 306,291

F1 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $101.24 to $102.22, inclusive. The Reporting Person undertakes 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 the ranges set forth in this footnote (1), footnote (3), footnote (4), footnote (5), footnote (6), and footnote (7).

F2 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026, (ii) 1,124 shares of restricted stock that vest on June 12, 2026, and (iii) 5,834 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: 0001415889-25-022636 · form4-08212025_090817.xml · nonDerivative · entry 1

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 313,291

F1 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $104.00 to $104.51, inclusive. The Reporting Person undertakes 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 the ranges set forth in this footnote.

F2 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026, (ii) 1,124 shares of restricted stock that vest on June 12, 2026, and (iii) 5,834 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: 0001415889-25-022509 · form4-08202025_090847.xml · nonDerivative · entry 2

EARLY CREIGHTON K · CIK 0000904702 · EXECUTIVE VP AND CFO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 73,681

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) 4,620 shares of restricted stock units that vest in three substantially equal installments on each of March 17, 2026, March 17, 2027 and March 17, 2028, (ii) 2,800 shares of restricted stock units that vest in two substantially equal installments on each of March 20, 2026 and March 20, 2027 and (iii) 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.

F3 · balance_after: Includes 348 shares of Common Stock purchased under the Amended and Restated Willdan Group, Inc. 2006 Employee Stock Purchase Plan on June 30, 2025.

SEC source: 0001415889-25-022509 · form4-08202025_090847.xml · nonDerivative · entry 1

EARLY CREIGHTON K · CIK 0000904702 · EXECUTIVE VP AND CFO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 75,151

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 effective on August 18, 2025, resulting in the immediate vesting of the restricted stock units as to 2,732 shares of Common Stock.

F2 · balance_after: Includes (i) 4,620 shares of restricted stock units that vest in three substantially equal installments on each of March 17, 2026, March 17, 2027 and March 17, 2028, (ii) 2,800 shares of restricted stock units that vest in two substantially equal installments on each of March 20, 2026 and March 20, 2027 and (iii) 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.

F3 · balance_after: Includes 348 shares of Common Stock purchased under the Amended and Restated Willdan Group, Inc. 2006 Employee Stock Purchase Plan on June 30, 2025.

SEC source: 0001415889-25-022508 · form4-08202025_090843.xml · nonDerivative · entry 2

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

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 207,542

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) 19,250 shares of restricted stock units that vest in three substantially equal installments on each of March 17, 2026, March 17, 2027 and March 17, 2028, (ii) 11,667 shares of restricted stock units that vest in two substantially equal installments on each of March 20, 2026 and March 20, 2027 and (iii) 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.

F3 · balance_after: Includes 386 shares of Common Stock purchased under the Amended and Restated Willdan Group, Inc. 2006 Employee Stock Purchase Plan on June 30, 2025.

SEC source: 0001415889-25-022508 · form4-08202025_090843.xml · nonDerivative · entry 1

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

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 214,330

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 effective on August 18, 2025, resulting in the immediate vesting of the restricted stock units as to 12,963 shares of Common Stock.

F2 · balance_after: Includes (i) 19,250 shares of restricted stock units that vest in three substantially equal installments on each of March 17, 2026, March 17, 2027 and March 17, 2028, (ii) 11,667 shares of restricted stock units that vest in two substantially equal installments on each of March 20, 2026 and March 20, 2027 and (iii) 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.

F3 · balance_after: Includes 386 shares of Common Stock purchased under the Amended and Restated Willdan Group, Inc. 2006 Employee Stock Purchase Plan on June 30, 2025.

SEC source: 0001415889-25-022507 · form4-08202025_090812.xml · nonDerivative · entry 2

CHEN MICAH · CIK 0001733678 · EXECUTIVE VP & GENERAL COUNSEL

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 40,423

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) 4,620 shares of restricted stock units that vest in three substantially equal installments on each of March 17, 2026, March 17, 2027 and March 17, 2028, (ii) 2,800 shares of restricted stock units that vest in two substantially equal installments on each of March 20, 2026 and March 20, 2027 and (iii) 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.

F3 · balance_after: Includes 386 shares of Common Stock purchased under the Amended and Restated Willdan Group, Inc. 2006 Employee Stock Purchase Plan on June 30, 2025.

SEC source: 0001415889-25-022507 · form4-08202025_090812.xml · nonDerivative · entry 1

CHEN MICAH · CIK 0001733678 · EXECUTIVE VP & GENERAL COUNSEL

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 41,620

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 effective on August 18, 2025, resulting in the immediate vesting of the restricted stock units as to 2,732 shares of Common Stock.

F2 · balance_after: Includes (i) 4,620 shares of restricted stock units that vest in three substantially equal installments on each of March 17, 2026, March 17, 2027 and March 17, 2028, (ii) 2,800 shares of restricted stock units that vest in two substantially equal installments on each of March 20, 2026 and March 20, 2027 and (iii) 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.

F3 · balance_after: Includes 386 shares of Common Stock purchased under the Amended and Restated Willdan Group, Inc. 2006 Employee Stock Purchase Plan on June 30, 2025.

SEC source: 0001415889-25-022512 · form4-08202025_090805.xml · derivative · entry 9

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 94,918

Underlying: Common Stock · 5,082 shares

Expires 2026-11-03

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.

F9 · 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 November 3, 2017, November 3, 2018 and November 3, 2019.

SEC source: 0001415889-25-022512 · form4-08202025_090805.xml · nonDerivative · entry 8

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 320,696

F8 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $111.00 to $111.44, inclusive.

F2 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026, (ii) 1,124 shares of restricted stock that vest on June 12, 2026, and (iii) 5,834 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: 0001415889-25-022512 · form4-08202025_090805.xml · nonDerivative · entry 7

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 327,902

F7 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $110.00 to $110.99, inclusive.

F2 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026, (ii) 1,124 shares of restricted stock that vest on June 12, 2026, and (iii) 5,834 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: 0001415889-25-022512 · form4-08202025_090805.xml · nonDerivative · entry 6

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 354,160

F6 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $109.00 to $109.99, inclusive.

F2 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026, (ii) 1,124 shares of restricted stock that vest on June 12, 2026, and (iii) 5,834 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: 0001415889-25-022512 · form4-08202025_090805.xml · nonDerivative · entry 5

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 412,463

F5 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $108.00 to $108.99, inclusive.

F2 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026, (ii) 1,124 shares of restricted stock that vest on June 12, 2026, and (iii) 5,834 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: 0001415889-25-022512 · form4-08202025_090805.xml · nonDerivative · entry 4

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 445,696

F4 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at $113.01.

F2 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026, (ii) 1,124 shares of restricted stock that vest on June 12, 2026, and (iii) 5,834 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: 0001415889-25-022512 · form4-08202025_090805.xml · nonDerivative · entry 3

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 445,996

F3 · price: The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $112.00 to $112.73, inclusive. The Reporting Person undertakes 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 the ranges set forth in this footnote (3), footnote (4), footnote (5), footnote (6), footnote (7) and footnote (8).

F2 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026, (ii) 1,124 shares of restricted stock that vest on June 12, 2026, and (iii) 5,834 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: 0001415889-25-022512 · form4-08202025_090805.xml · nonDerivative · entry 2

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 450,778

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.

F2 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026, (ii) 1,124 shares of restricted stock that vest on June 12, 2026, and (iii) 5,834 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: 0001415889-25-022512 · form4-08202025_090805.xml · nonDerivative · entry 1

Brisbin Thomas Donald · CIK 0001395188 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 445,696

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 effective on August 18, 2025, resulting in the immediate vesting of the restricted stock units as to 21,461 shares of Common Stock.

F2 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026, (ii) 1,124 shares of restricted stock that vest on June 12, 2026, and (iii) 5,834 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: 0001415889-25-022198 · form4-08182025_090848.xml · nonDerivative · entry 1

Downes Cynthia · CIK 0001518288 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 8,909

F1 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026 and (ii) 1,124 shares of restricted stock that vest on June 12, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001415889-25-022196 · form4-08182025_090852.xml · nonDerivative · entry 1

REDER WANDA KAY · CIK 0001895686 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 10,676

F1 · balance_after: Includes (i) 1,781 shares of restricted stock that vest on June 11, 2026 and (ii) 1,124 shares of restricted stock that vest on June 12, 2026, subject to the Reporting Person's continued service to the Issuer through the applicable vesting date.

SEC source: 0001415889-25-022106 · form4-08152025_090857.xml · derivative · entry 3

EARLY CREIGHTON K · CIK 0000904702 · EXECUTIVE VP AND CFO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 7,764 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.

F2 · 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.