Entry into a Material Definitive Agreement The information related to the Amendment (as defined below) set forth under

Completion of Acquisition or Disposition of Assets As previously reported, on September 22, 2026, Willdan Group, Inc. (the “Company”), through its wholly owned subsidiary, Willdan Energy Solutions, Inc. (“Energy Solutions”), entered into that certain Membership Interest Purchase Agreement, among Mantis Intermediate Holdings, LLC (“Mantis”), Mantis NewCo, LLC (“Seller”), Willdan and Energy Solutions (the “Purchase Agreement”) to acquire one hundred percent of the issued and outstanding equity…

Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant On October 30, 2026, the Company entered into an Increase Request and Second Amendment to Amended and Restated Credit Agreement (the “Amendment”) among the Company, certain subsidiaries of the Company party thereto, the Lenders (as defined below) party thereto, and BMO Harris Bank, N.A., as administrative agent (in such capacity, the “Agent”), which amends the Company’s existing A…

Results of Operations and Financial Condition Willdan Group, Inc. (“Willdan”) issued a press release on November 5, 2026. The press release announced Willdan’s financial results for the third quarter ended October 2, 2026. A copy of the press release is attached as Exhibit 99.1 hereto and is hereby incorporated herein by reference in its entirety. The information in this

Entry into a Material Definitive Agreement On September 22, 2026, Willdan Energy Solutions, Inc. (“Energy Solutions”), a wholly owned subsidiary of Willdan Group, Inc. (“Willdan”), entered into a Membership Interest Purchase Agreement (the “Purchase Agreement”) with Mantis NewCo, LLC (“Seller”), pursuant to which Seller agreed to sell one hundred percent of the issued and outstanding equity securities (the “Subject Securities”) of Mantis Intermediate Holdings, LLC (the “Intermediate”) to Ener…

Results of Operations and Financial Condition Willdan Group, Inc. (“Willdan”) issued a press release on August 6, 2026. The press release announced Willdan’s financial results for the second quarter ended July 3, 2026. A copy of the press release is attached as Exhibit 99.1 hereto and is hereby incorporated herein by reference in its entirety. The information in this

The filing pertains to compensatory arrangements and amendments to the performance incentive plan, not a management change.

Results of Operations and Financial Condition Willdan Group, Inc. (“Willdan”) issued a press release on May 7, 2026. The press release announced Willdan’s financial results for the first quarter ended April 3, 2026. A copy of the press release is attached as Exhibit 99.1 hereto and is hereby incorporated herein by reference in its entirety. The information in this

Results of Operations and Financial Condition Willdan Group, Inc. (“Willdan”) issued a press release on February 26, 2026. The press release announced Willdan’s financial results for the fourth quarter and fiscal year ended January 2, 2026. A copy of the press release is attached as Exhibit 99.1 hereto and is hereby incorporated herein by reference in its entirety. The information in this

Results of Operations and Financial Condition Willdan Group, Inc. (“Willdan”) issued a press release on November 6, 2025. The press release announced Willdan’s financial results for the third quarter ended October 3, 2025. A copy of the press release is attached as Exhibit 99.1 hereto and is hereby incorporated herein by reference in its entirety. The information in this

Results of Operations and Financial Condition Willdan Group, Inc. (“Willdan”) issued a press release on August 7, 2025. The press release announced Willdan’s financial results for the second quarter ended July 4, 2025. A copy of the press release is attached as Exhibit 99.1 hereto and is hereby incorporated herein by reference in its entirety. The information in this

The filing pertains to compensatory arrangements and amendments to the performance incentive plan, not a management change.

Results of Operations and Financial Condition Willdan Group, Inc. (“Willdan”) issued a press release on May 8, 2025. The press release announced Willdan’s financial results for the first quarter ended April 4, 2025. A copy of the press release is attached as Exhibit 99.1 hereto and is hereby incorporated herein by reference in its entirety. The information in this

Results of Operations and Financial Condition Willdan Group, Inc. (“Willdan”) issued a press release on March 6, 2025. The press release announced Willdan’s financial results for the fourth quarter and fiscal year ended December 27, 2024. A copy of the press release is attached as Exhibit 99.1 hereto and is hereby incorporated herein by reference in its entirety. The information in this

New employment agreements were signed with senior executives, outlining their compensation and severance benefits.

Results of Operations and Financial Condition Willdan Group, Inc. (“Willdan”) issued a press release on October 31, 2024. The press release announced Willdan’s financial results for the third quarter ended September 27, 2024. A copy of the press release is attached as Exhibit 99.1 hereto and is hereby incorporated herein by reference in its entirety. The information in this

Results of Operations and Financial Condition Willdan Group, Inc. (“Willdan”) issued a press release on August 1, 2024. The press release announced Willdan’s financial results for the second quarter ended June 28, 2024. A copy of the press release is attached as Exhibit 99.1 hereto and is hereby incorporated herein by reference in its entirety. The information in this

The filing pertains to compensatory arrangements and amendments to the performance incentive plan, not a management change.

Results of Operations and Financial Condition Willdan Group, Inc. (“Willdan”) issued a press release on May 2, 2024. The press release announced Willdan’s financial results for the first quarter ended March 29, 2024. A copy of the press release is attached as Exhibit 99.1 hereto and is hereby incorporated herein by reference in its entirety. The information in this

Results of Operations and Financial Condition Willdan Group, Inc. (“Willdan”) issued a press release on March 7, 2024. The press release announced Willdan’s financial results for the fourth quarter and fiscal year ended December 29, 2023. A copy of the press release is attached as Exhibit 99.1 hereto and is hereby incorporated herein by reference in its entirety. The information in this

Director — Keith W. Renken: Mr. Renken retired and resigned from the Board of Directors.

Chief Executive Officer — Thomas D. Brisbin: Dr. Brisbin resigned as CEO and entered into a consulting agreement with the company.

CEO — Thomas D. Brisbin: Dr. Brisbin is retiring from the CEO role but will continue as Chairman of the Board, and Michael A. Bieber has been appointed as the new President and CEO.

Results of Operations and Financial Condition Willdan Group, Inc. (“Willdan”) issued a press release on November 2, 2023. The press release announced Willdan’s financial results for the third quarter ended September 29, 2023. A copy of the press release is attached as Exhibit 99.1 hereto and is hereby incorporated herein by reference in its entirety. The information in this

Material Modification to Rights of Security Holders. As noted above under