# EDGAR Filing Document

**Accession Number:** 0001113232
**File Stem:** 0001990732-26-000006
**Filing Date:** 2026-5
**Character Count:** 9410
**Document Hash:** 400a865ecf8c8dac3d7d3fdf87342999
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001990732-26-000006.hdr.sgml**: 20260519

**ACCESSION NUMBER**: 0001990732-26-000006

**CONFORMED SUBMISSION TYPE**: 4

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20260515

**FILED AS OF DATE**: 20260519

**DATE AS OF CHANGE**: 20260519

**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Tatnall Christopher
- **CENTRAL INDEX KEY:** 0001990732

**ORGANIZATION NAME:**

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 000-30941
- **FILM NUMBER:** 261000121

**MAIL ADDRESS:**
- **STREET 1:** AXCELIS TECHNOLOGIES INC.
- **STREET 2:** 108 CHERRY HILL DRIVE
- **CITY:** BEVERLY
- **STATE:** MA
- **ZIP:** 01915
**ISSUER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** AXCELIS TECHNOLOGIES INC
- **CENTRAL INDEX KEY:** 0001113232
- **STANDARD INDUSTRIAL CLASSIFICATION:** SPECIAL INDUSTRY MACHINERY, NEC [3559]
- **ORGANIZATION NAME:** 06 Technology
- **EIN:** 341818596
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**BUSINESS ADDRESS:**
- **STREET 1:** 108 CHERRY HILL DRIVE
- **CITY:** BEVERLY
- **STATE:** MA
- **ZIP:** 01915
- **BUSINESS PHONE:** 978-787-4000

**MAIL ADDRESS:**
- **STREET 1:** 108 CHERRY HILL DRIVE
- **CITY:** BEVERLY
- **STATE:** MA
- **ZIP:** 01915

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** EATON SEMICONDUCTOR EQUIPMENT INC
- **DATE OF NAME CHANGE:** 20000501

### 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>Tatnall Christopher<br><sub>(Last) (First) (Middle)</sub><br>C/O AXCELIS TECHNOLOGIES, INC.<br>108 CHERRY HILL DRIVE<br><sub>(Street)</sub><br>BEVERLY, MA 01915<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2026-05-15 | **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>_EVP Global Customer Operations_ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>AXCELIS TECHNOLOGIES INC [ ACLS ] | **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 | 2026-05-15 |  | A |  | 3504 | A | 0<sup>(1)</sup> | 26548<sup>(2)</sup> | D |  |
| Common Stock | 2026-05-15 |  | A |  | 3504 | A | 0<sup>(3)</sup> | 30052<sup>(4)</sup> | D |  |
| Common Stock | 2026-05-15 |  | F |  | 744 | D<sup>(5)</sup> | 155.18<sup>(6)</sup> | 29308<sup>(7)</sup> | D |  |
| Common Stock | 2026-05-15 |  | F |  | 345 | D<sup>(8)</sup> | 155.18<sup>(6)</sup> | 28963<sup>(9)</sup> | D |  |
| Common Stock | 2026-05-15 |  | F |  | 170 | D<sup>(10)</sup> | 155.18<sup>(6)</sup> | 28793<sup>(11)</sup> | 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 |
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

---

### Footnotes:

(1) These shares are issuable on vesting of restricted stock units granted under the Company's 2012 Equity Incentive Plan on May 15, 2026. Assuming continuation of employment, these restricted stock units will vest as to one-third of the shares granted on each of May 15, 2027, May 15, 2028, and May 15, 2029.

(2) Of the shares held following this grant on May 15, 2026, 19,967 were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.

(3) These shares are issuable on vesting of restricted stock units granted under the Company's 2012 Equity Incentive Plan on May 15, 2026. In this grant, the executive may earn shares of common stock, ranging from zero to 200% of the granted units. The shares are earned based on the achievement of performance goals based on relative total shareholder return over a performance period of January 1, 2026 to December 31, 2028. Assuming continuation of employment, 100% of the earned shares will vest on measurement of performance in 2029. Unearned restricted stock units will forfeit at such time.

(4) Of the shares held after this grant on May 15, 2026, 23,471 shares were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.

(5) This forfeiture of shares for tax withholding purposes relates to the vesting on May 15, 2026 of service vesting restricted stock units granted to the executive in May 2025. The shares issued to the executive on the vesting were reduced by a number of shares having a value equal to the executive's tax withholding obligation with respect to the vested restricted stock units.

(6) Represents the closing price of the common stock on the date of the tax withholding.

(7) Of the shares held after this vesting event on May 15, 2026, 21,934 were issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture.

(8) This forfeiture of shares for tax withholding purposes relates to the vesting on May 15, 2026 of service vesting restricted stock units granted to the executive in May 2024. The shares issued to the executive on the vesting were reduced by a number of shares having a value equal to the executive's tax withholding obligation with respect to the vested restricted stock units.

(9) Of the shares held after this vesting event on May 15, 2026, 21,221 were issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture.

(10) This forfeiture of shares for tax withholding purposes relates to the vesting on May 15, 2026 of service vesting restricted stock units granted to the executive in May 2023. The shares issued to the executive on the vesting were reduced by a number of shares having a value equal to the executive's tax withholding obligation with respect to the vested restricted stock units.

(11) Of the shares held after this vesting event on May 15, 2026, 20,871 were issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture.

**Signature:** /s/ Eileen J. Evans, Attorney-in-Fact  
**Date:** 2026-05-19

### 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.**