Company: HCKT
Filing Date: 2025-11-04
Form Type: SC TO-C
Source: 0001193125-25-265008
Chunk: 2

Company: HACKETT GROUP, INC.
Filing Date: 2025-11-04
Form: SC TO-C
Chunk 2
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 will be filing with the SEC at the SEC’s website at www.sec.gov or from the Company’s information agent for the tender offer.

| Item 9.01 | Financial Statements and Exhibits. |

(d) Exhibits

| Exhibit 
 Number  
 99.1    |     | Description                                                                                          
 Press Release of The Hackett Group, Inc., dated November 4, 2025                                     |
|:--------|:----|:-----------------------------------------------------------------------------------------------------|
| 104     |     | Cover Page Interactive Data File (the cover page XBRL tags are embedded in the Inline XBRL document) |

SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

| Date: November 4, 2025 |     | THE HACKETT GROUP, INC. 
 By:                     |     | /s/ Robert A. Ramirez                       |
|:-----------------------|:----|:------------------------|:----|:--------------------------------------------|
|                        |     |                         |     | Robert A. Ramirez                           |
|                        |     |                         |     | Executive Vice President, Finance and Chief 
 Financial Officer                           |

| WWW.THEHACKETTGROUP.COM |

Exhibit 99.1 The Hackett Group Announces Third Quarter 2025 Results and Intent to Launch Dutch Tender Offer MIAMI – November 4, 2025 – The Hackett Group, Inc.(NASDAQ: HCKT), a leading generative artificial intelligence (Gen AI) consultancy and executive advisory firm that enables Digital World Class ®performance, today announced its financial results for the third quarter, which ended on September 26, 2025. “We reported operating results that were at the mid-rangeof our adjusted earnings per share guidance. This was achieved while continuing our pivot to Gen AI, including aggressively investing in our highly differentiating AI XPLR platform and growing our Gen AI revenues,” stated Ted A. Fernandez, Chairman and CEO of The Hackett Group, Inc. “What distinguished this quarter was the release of our AI XPLR V4 in September and the overwhelmingly positive response to our new capabilities and described by one of our channel partners as game changing. AI XPLR V4 fully considers the client’s existing automation footprint and data sources at a level of detail to identify and design agentic workflows, which ensures implementation success and value realization with unprecedented speed. More importantly