Axcelis (ACLS) CEO uses 711 shares for RSU tax withholding, holds 154,900

Rhea-AI Filing Summary

Axcelis Technologies President and CEO Russell Low reported a routine tax-related share disposition. On May 18, 2026, 711 shares of common stock were withheld at $146.24 per share to satisfy tax obligations from the vesting of restricted stock units granted in May 2022.

After this event, Low directly held 154,900 shares. Footnotes state that 106,691 of the shares held after the May 16, 2026 vesting date are issuable upon future vesting of restricted stock units under the 2012 Equity Incentive Plan and remain subject to forfeiture.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider Low Russell

Role PRESIDENT AND CEO

Type	Security	Shares	Price	Value
Tax Withholding	Common Stock	711	$146.24	$104K

Holdings After Transaction: Common Stock — 154,900 shares (Direct, null)

Footnotes (1)

1. This forfeiture of shares for tax withholding purposes relates to the vesting on May 16, 2026 of service vesting restricted stock units granted to the executive in May 2022. 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. Represents the closing price of the common stock on the date of the tax withholding. Of the shares held after this vesting event on May 16, 2026, 106,691 were issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture.

Key Figures

Tax-withholding shares: 711 shares Price per share: $146.24 per share Shares held after transaction: 154,900 shares +1 more

4 metrics

Tax-withholding shares 711 shares Shares forfeited for tax withholding on May 18, 2026

Price per share $146.24 per share Closing price on tax-withholding date

Shares held after transaction 154,900 shares Direct holdings after tax-withholding disposition

Unvested RSU-linked shares 106,691 shares Issuable upon future vesting under 2012 Equity Incentive Plan

Key Terms

restricted stock units, tax withholding, closing price, 2012 Equity Incentive Plan

4 terms

restricted stock units financial

"service vesting restricted stock units granted to the executive in May 2022"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

tax withholding financial

"forfeiture of shares for tax withholding purposes relates to the vesting"

Tax withholding is the practice of taking a portion of a payment—such as wages, dividends, or sale proceeds—before it reaches the recipient and sending that portion to the tax authority as an advance on the recipient’s eventual tax bill. For investors it matters because withholding reduces immediate cash received and affects after‑tax returns, estimated tax payments, and whether you may owe more or receive a refund when taxes are finally calculated, like having a small automatic savings set aside for your tax bill.

closing price financial

"Represents the closing price of the common stock on the date of the tax withholding"

2012 Equity Incentive Plan financial

"granted to the reporting person under the 2012 Equity Incentive Plan"

Form 4 Insider Transactions: What Each Field Means →

SEC Form 4

FORM 4

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

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

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^*

Low Russell

(Last) (First) (Middle)

C/O AXCELIS TECHNOLOGIES, INC.

108 CHERRY HILL DRIVE

(Street)

BEVERLY MASSACHUSETTS 01915

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
AXCELIS TECHNOLOGIES INC [ ACLS ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	PRESIDENT AND CEO

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
05/18/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	05/18/2026		F		711	D(1)	$146.24(2)	154,900(3)	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. This forfeiture of shares for tax withholding purposes relates to the vesting on May 16, 2026 of service vesting restricted stock units granted to the executive in May 2022. 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.

2. Represents the closing price of the common stock on the date of the tax withholding.

3. Of the shares held after this vesting event on May 16, 2026, 106,691 were issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture.

	/s/ Eileen J. Evans, Attorney-in-Fact	05/20/2026
	** Signature of Reporting Person	Date
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.
* Form 4: SEC 1474 (03-26)

FAQ

What insider transaction did Axcelis Technologies (ACLS) report for CEO Russell Low?

Axcelis CEO Russell Low reported a tax-related share disposition. 711 common shares were withheld to cover tax on vested restricted stock units, a non-market event that did not involve an open-market purchase or sale of shares.

How many Axcelis (ACLS) shares were used for Russell Low’s tax withholding?

The filing shows 711 Axcelis common shares were withheld for tax obligations. The disposition relates to restricted stock units vesting in May 2026, using shares instead of cash to satisfy the executive’s tax liability on that vesting.

At what price were the withheld Axcelis (ACLS) shares valued in the Form 4?

The withheld shares were valued at $146.24 per share, representing the closing price on the tax withholding date. This price is used solely for reporting the value of shares applied to satisfy the executive’s tax obligation.

How many Axcelis (ACLS) shares does Russell Low hold after this transaction?

After the tax-withholding disposition, Russell Low directly held 154,900 Axcelis common shares. This figure reflects his post-transaction position, showing that the number of shares withheld for taxes was small relative to his remaining direct holdings.

What restricted stock units does Russell Low still have at Axcelis (ACLS)?

Footnotes state that 106,691 shares were issuable after May 16, 2026 upon vesting of restricted stock units under the 2012 Equity Incentive Plan. These units have not fully vested and remain subject to forfeiture until service conditions are met.

Was Russell Low’s Axcelis (ACLS) Form 4 transaction an open-market sale?

No, the Form 4 describes a tax-withholding disposition, not an open-market sale. Shares were forfeited back to satisfy tax obligations on vested restricted stock units, a common administrative mechanism rather than a discretionary sale into the market.