# EDGAR Filing Document

**Accession Number:** 0001018963
**File Stem:** 0001193125-26-006554
**Filing Date:** 2026-1
**Character Count:** 8765
**Document Hash:** 47065e58373d3f53b2f73a5246462c03
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-26-006554.hdr.sgml**: 20260107

**ACCESSION NUMBER**: 0001193125-26-006554

**CONFORMED SUBMISSION TYPE**: 4

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20260105

**FILED AS OF DATE**: 20260107

**DATE AS OF CHANGE**: 20260107

**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Harris Timothy J
- **CENTRAL INDEX KEY:** 0001776844

**ORGANIZATION NAME:**

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-12001
- **FILM NUMBER:** 26516606

**MAIL ADDRESS:**
- **STREET 1:** C/O ATI INC.
- **STREET 2:** 2021 MCKINNEY AVENUE
- **CITY:** DALLAS
- **STATE:** TX
- **ZIP:** 75201
**ISSUER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** ATI INC
- **CENTRAL INDEX KEY:** 0001018963
- **STANDARD INDUSTRIAL CLASSIFICATION:** STEEL PIPE & TUBES [3317]
- **ORGANIZATION NAME:** 04 Manufacturing
- **EIN:** 251792394
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1228

**BUSINESS ADDRESS:**
- **STREET 1:** 2021 MCKINNEY AVENUE
- **CITY:** DALLAS
- **STATE:** TX
- **ZIP:** 75201
- **BUSINESS PHONE:** 4123942800

**MAIL ADDRESS:**
- **STREET 1:** 2021 MCKINNEY AVENUE
- **CITY:** DALLAS
- **STATE:** TX
- **ZIP:** 75201

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** ALLEGHENY TECHNOLOGIES INC
- **DATE OF NAME CHANGE:** 19991213

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** ALLEGHENY TELEDYNE INC
- **DATE OF NAME CHANGE:** 19960716

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## FORM 4

### STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

[ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

[ ] Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>Harris Timothy J<br><sub>(Last) (First) (Middle)</sub><br>C/O ATI INC.<br>2021 MCKINNEY AVE., SUITE 1100<br><sub>(Street)</sub><br>DALLAS, TX 75201<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2026-01-05 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director [ ] 10% Owner<br>[X] Officer (give title below) [ ] Other (specify below)<br>_Senior VP and CDIO_ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>ATI INC [ ATI ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[X] Form filed by One Reporting Person<br>[ ] Form filed by More than One Reporting Person |

---

## Table I - Non-Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | 3. Transaction Code (V) | 3. Transaction Code (V) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | Code | V | Amount | (A) or (D) | Price | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| Common Stock, par value $0.10 per share | 2026-01-05 |  | A |  | 2677<sup>(1)</sup> | A | 0<sup>(2)</sup> | 100987 | D |  |
| Common Stock, par value $0.10 per share | 2026-01-05 |  | M |  | 70442 | A | 0.00<sup>(3)</sup> | 171429 | D |  |
| Common Stock, par value $0.10 per share | 2026-01-05 |  | F |  | 30918<sup>(4)</sup> | D | 121.08<sup>(5)</sup> | 140511 | D |  |
| Common Stock, par value $0.10 per share | 2026-01-05 |  | A |  | 46318<sup>(6)</sup> | A | 0.00<sup>(2)</sup> | 186829 | D |  |
| Common Stock, par value $0.10 per share | 2026-01-05 |  | F |  | 20283<sup>(7)</sup> | D | 121.08<sup>(5)</sup> | 166546 | D |  |
| Common Stock, par value $0.10 per share | 2026-01-05 |  | F |  | 3359<sup>(8)</sup> | D | 121.08<sup>(5)</sup> | 163187 | D |  |

---

## Table II - Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | 4. Transaction Code (V) | 4. Transaction Code (V) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 6. Date Exercisable and Expiration Date | 6. Date Exercisable and Expiration Date | 7. Title and Amount of Underlying Securities | 7. Title and Amount of Underlying Securities | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | Code | V | (A) | (D) | Date Exercisable | Expiration Date | Title | Amount or Number of Shares | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
| Performance Stock Unit | 0.00<sup>(3)</sup> | 2026-01-05 |  | M |  |  | 25641 | 2026-12-31<sup>(3)</sup> | 2026-12-31<sup>(3)</sup> | Common Stock, par value $0.10 per share | 70442 | 0.00<sup>(3)</sup> | 25641 | D |  |

---

### Footnotes:

(1) Award of restricted stock units, which are settled in shares of stock upon vesting.  The award vests in three equal annual installments on each of the first three anniversaries of the grant date.

(2) Awarded under the Issuer's 2022 Incentive Plan.

(3) Settlement of one-half of certain Performance Stock Units awarded in 2022 ("2022 Breakout Performance Units"), each of which represented a contingent right to receive shares of the Issuer's Common Stock if the Issuer's Common Stock achieved specified target market prices (based on a 20-trading day average) on the New York Stock Exchange ("NYSE") for at least 20 consecutive trading days (the "20-day Average Market Price") prior to December 31, 2025, up to a maximum of three shares per Unit. The shares underlying one-half of the 2022 Breakout Performance Units became payable as of January 5, 2026 following certification of the Issuer's achievement of the relevant performance criteria by the Compensation and Leadership Development Committee of the Company's Board of Directors (the "CLDC").  The remaining half of the 2022 Breakout Performance Units are scheduled by their terms to become payable in early 2027.

(4) Shares withheld for the payment of taxes in connection with the settlement of 2022 Breakout Performance Units.

(5) Represents the average of the high and low trading prices for one share of the Issuer's Common Stock on the NYSE on January 5, 2026.

(6) Settlement of performance-vested restricted stock units that were granted in 2023, the vesting of which was contingent on the Issuer's total shareholder return relative to a specified peer group during the period from January 1, 2023 through December 31, 2025 (the "2023-2025 PSUs").  The shares underlying the 2023-2025 PSUs became payable as of January 5, 2026 following certification of the Issuer's achievement of the relevant performance criteria by the CLDC.

(7) Shares withheld for the payment of taxes in connection with the settlement of the 2023-2025 PSUs.

(8) Shares withheld for payment of taxes on restricted stock units awarded in 2023, 2024 and 2025.  One third of each such award vested by the terms thereof on January 5, 2026.

**Signature:** /s/ Amanda J. Skov, Attorney-in-Fact for Timothy J. Harris  
**Date:** 2026-01-07

### Remarks:

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.

**Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.**