[Form 4] ATN International, Inc. Insider Trading Activity

Rhea-AI Filing Summary

PRIOR MICHAEL T reported acquisition or exercise transactions in this Form 4 filing.

ATN International executive chairman Michael T. Prior received new equity awards in the form of restricted stock units and performance-based RSUs. On March 17, 2026 he was granted 13,524 performance-based RSUs, each representing a contingent right to one share of common stock, and 13,524 shares of common stock via a stock-based award. The time-based restricted stock units will vest in four equal installments on March 17 of 2027, 2028, 2029 and 2030. The performance-based RSUs may deliver between zero and 150% of the 13,524 target shares based on relative total shareholder return versus the Russell 2000 Index over a performance period from March 17, 2026 to March 17, 2029. Following these awards, Prior directly holds 590,051 shares of ATN International common stock.

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

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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^*

PRIOR MICHAEL T

(Last) (First) (Middle)

C/O ATN INTERNATIONAL, INC.

500 CUMMINGS CENTER

(Street)

BEVERLY MASSACHUSETTS 01915

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
ATN International, Inc. [ ATNI ]

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

X	Director		10% Owner
	Officer (give title below)	X	Other (specify below)
			EXECUTIVE CHAIRMAN

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
03/17/2026

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	03/17/2026		A		13,524(1)	A	$0	590,051	D
Common Stock								128,847	I	Trustee of Lauren S. Prior 2013 Trust
Common Stock								8,141	I	Trustee of JP 2018 Trust
Common Stock								7,741	I	Trustee of WP 2015 Trust
Common Stock								8,041	I	Trustee of RP 2014 Trust
Common Stock								7,982	I	Trustee of Prior Family Trust 2019

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
Performance-Based Restricted Stock Units	$0	03/17/2026		A		13,524(2)		(3)	(3)	Common Stock	13,524	$0	13,524	D

Explanation of Responses:

1. The securities described are restricted stock units and will fest in four equal installments on each of March 17, 2027, 2028, 2029 and 2030. Upon vesting Mr. Prior will receive a number of shares of common stock equal to the number of restricted stocks units that have vested.

2. Each performance-based RSU ("PSU") represents a contingent right to receive one share of the Issuer's common stock, subject to the achievement of pre-established relative total shareholder return ("TSR") goals that were set by the Compensation Committee of the Issuer's Board of Directors, based on comparing the Issuer's TSR relative to the TSR of the Russell 2000 Index, using the average closing price of the shares for the 40 days before and including each of the first and last days of the applicable performance period. The aggregate number of shares issued may range from zero (0) shares to 150% of the target number of shares reported in columns 7 and 9 of this report.

3. Between zero (0) and 150% of the PSUs will generally vest, if at all, as of the end of the performance period that begins on March 17, 2026, and ends on March 17, 2029.

	/s/ Michael T. Prior	03/27/2026
	** 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 equity awards did ATNI executive chairman Michael Prior receive?

Michael Prior received 13,524 performance-based RSUs and 13,524 shares of common stock as stock-based awards. These grants are compensation-related, made at no cash cost to him, and increase his direct equity exposure to ATN International.

How do Michael Prior’s performance-based RSUs at ATNI vest?

The performance-based RSUs may deliver between zero and 150% of 13,524 target shares. Vesting depends on ATN International’s total shareholder return versus the Russell 2000 Index over a performance period running from March 17, 2026 through March 17, 2029.

What is the vesting schedule for Michael Prior’s time-based RSUs at ATNI?

The time-based restricted stock units will vest in four equal installments. Vesting dates fall on March 17 of 2027, 2028, 2029 and 2030, after which Michael Prior will receive an equivalent number of ATN International common shares.

Did Michael Prior buy or sell ATNI shares in this Form 4 filing?

The Form 4 shows compensation-related equity awards, not open-market buying or selling. Michael Prior received restricted stock units and common shares at a grant price of zero, with no reported open-market purchases or sales in this filing.

How many ATNI common shares does Michael Prior hold directly after these grants?

After the March 17, 2026 awards, Michael Prior directly holds 590,051 shares of ATN International common stock. This figure reflects his post-transaction direct ownership, separate from additional shares held indirectly through various family trusts.

What performance metric governs Michael Prior’s ATNI performance-based RSUs?

The performance-based RSUs depend on relative total shareholder return versus the Russell 2000 Index. The calculation uses average closing prices over 40 days at the start and end of the March 17, 2026 to March 17, 2029 performance period to determine payout.