SCHEDULE 13D

CUSIP No.

L6388F110

1

Name of reporting person

Atlas Investissement SAS

2

Check the appropriate box if a member of a Group (See Instructions)

(a)

(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

Checkbox not checked

6

Citizenship or place of organization

FRANCE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 70,470,018.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 70,470,018.00

11

Aggregate amount beneficially owned by each reporting person

70,470,018.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

13

Percent of class represented by amount in Row (11)

42.2 %

14

Type of Reporting Person (See Instructions)

CO

Comment for Type of Reporting Person:

(1) Reflects 70,470,018 common shares, par value $1.50 per share ("Common Shares") of Millicom International Cellular S.A., a Luxembourg company (the "Issuer"), beneficially owned by Atlas Investissement SAS, a company incorporated under French law as a societe par actions simplifiee ("Atlas Investissement"). Iliad Holding SAS ("Iliad Holding"), as the controlling shareholder of Atlas Investissement, may be deemed to have shared beneficial ownership over the Common Shares beneficially owned by Atlas Investissement. Maya SAS ("Maya"), as the controlling shareholder of Iliad Holding, may be deemed to have shared beneficial ownership over the Common Shares beneficially owned by Iliad Holding and Atlas Investissement. Xavier Niel, the President of Maya, Jules Niel, John Niel, Elisa Niel and Joseph Niel (together, the "Niel Family") may be deemed to have shared beneficial ownership over the Common Shares beneficially owned by Atlas Investissement, Iliad Holding and Maya. (2) The percentage reflected in row 13 in the table above is calculated on the basis of 167,083,756 Common Shares outstanding as of July 31, 2025 (169,000,000 Common Shares outstanding, less 1,916,244 Common Shares held in treasury), as set forth in the last relevant update available on the date hereof on the Issuer's website.

SCHEDULE 13D

CUSIP No.

L6388F110

1

Name of reporting person

Iliad Holding SAS

2

Check the appropriate box if a member of a Group (See Instructions)

(a)

(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

Checkbox not checked

6

Citizenship or place of organization

FRANCE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 70,470,018.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 70,470,018.00

11

Aggregate amount beneficially owned by each reporting person

70,470,018.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

13

Percent of class represented by amount in Row (11)

42.2 %

14

Type of Reporting Person (See Instructions)

CO

Comment for Type of Reporting Person:

(1) Reflects 70,470,018 Common Shares beneficially owned by Atlas Investissement. Iliad Holding, as the controlling shareholder of Atlas Investissement, may be deemed to have shared beneficial ownership over the Common Shares beneficially owned by Atlas Investissement. Maya, as the controlling shareholder of Iliad Holding, may be deemed to have shared beneficial ownership over the Common Shares beneficially owned by Iliad Holding and Atlas Investissement. The Niel Family may be deemed to have shared beneficial ownership over the Common Shares beneficially owned by Atlas Investissement, Iliad Holding and Maya. (2) The percentage reflected in row 13 in the table above is calculated on the basis of 167,083,756 Common Shares outstanding as of July 31, 2025 (169,000,000 Common Shares outstanding, less 1,916,244 Common Shares held in treasury), as set forth in the last relevant update available on the date hereof on the Issuer's website.

SCHEDULE 13D

CUSIP No.

L6388F110

1

Name of reporting person

Maya SAS

2

Check the appropriate box if a member of a Group (See Instructions)

(a)

(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

Checkbox not checked

6

Citizenship or place of organization

FRANCE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 70,470,018.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 70,470,018.00

11

Aggregate amount beneficially owned by each reporting person

70,470,018.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

13

Percent of class represented by amount in Row (11)

42.2 %

14

Type of Reporting Person (See Instructions)

CO

Comment for Type of Reporting Person:

(1) Reflects 70,470,018 Common Shares beneficially owned by Atlas Investissement. Iliad Holding, as the controlling shareholder of Atlas Investissement, may be deemed to have shared beneficial ownership over the Common Shares beneficially owned by Atlas Investissement. Maya, as the controlling shareholder of Iliad Holding, may be deemed to have shared beneficial ownership over the Common Shares beneficially owned by Iliad Holding and Atlas Investissement. The Niel Family may be deemed to have shared beneficial ownership over the Common Shares beneficially owned by Atlas Investissement, Iliad Holding and Maya. (2) The percentage reflected in row 13 in the table above is calculated on the basis of 167,083,756 Common Shares outstanding as of July 31, 2025 (169,000,000 Common Shares outstanding, less 1,916,244 Common Shares held in treasury), as set forth in the last relevant update available on the date hereof on the Issuer's website.

SCHEDULE 13D

CUSIP No.

L6388F110

1

Name of reporting person

Xavier Niel

2

Check the appropriate box if a member of a Group (See Instructions)

(a)

(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

Checkbox not checked

6

Citizenship or place of organization

FRANCE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 70,470,018.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 70,470,018.00

11

Aggregate amount beneficially owned by each reporting person

70,470,018.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

13

Percent of class represented by amount in Row (11)

42.2 %

14

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person:

(1) Reflects 70,470,018 Common Shares beneficially owned by Atlas Investissement. Iliad Holding, as the controlling shareholder of Atlas Investissement, may be deemed to have shared beneficial ownership over the Common Shares beneficially owned by Atlas Investissement. Maya, as the controlling shareholder of Iliad Holding, may be deemed to have shared beneficial ownership over the Common Shares beneficially owned by Iliad Holding and Atlas Investissement. The Niel Family may be deemed to have shared beneficial ownership over the Common Shares beneficially owned by Atlas Investissement, Iliad Holding and Maya. (2) The percentage reflected in row 13 in the table above is calculated on the basis of 167,083,756 Common Shares outstanding as of July 31, 2025 (169,000,000 Common Shares outstanding, less 1,916,244 Common Shares held in treasury), as set forth in the last relevant update available on the date hereof on the Issuer's website.

SCHEDULE 13D

CUSIP No.

L6388F110

1

Name of reporting person

Jules Niel

2

Check the appropriate box if a member of a Group (See Instructions)

(a)

(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

Checkbox not checked

6

Citizenship or place of organization

FRANCE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 70,470,018.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 70,470,018.00

11

Aggregate amount beneficially owned by each reporting person

70,470,018.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

13

Percent of class represented by amount in Row (11)

42.2 %

14

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person:

(1) Reflects 70,470,018 Common Shares beneficially owned by Atlas Investissement. Iliad Holding, as the controlling shareholder of Atlas Investissement, may be deemed to have shared beneficial ownership over the Common Shares beneficially owned by Atlas Investissement. Maya, as the controlling shareholder of Iliad Holding, may be deemed to have shared beneficial ownership over the Common Shares beneficially owned by Iliad Holding and Atlas Investissement. The Niel Family may be deemed to have shared beneficial ownership over the Common Shares beneficially owned by Atlas Investissement, Iliad Holding and Maya. (2) The percentage reflected in row 13 in the table above is calculated on the basis of 167,083,756 Common Shares outstanding as of July 31, 2025 (169,000,000 Common Shares outstanding, less 1,916,244 Common Shares held in treasury), as set forth in the last relevant update available on the date hereof on the Issuer's website.

SCHEDULE 13D

CUSIP No.

L6388F110

1

Name of reporting person

John Niel

2

Check the appropriate box if a member of a Group (See Instructions)

(a)

(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

Checkbox not checked

6

Citizenship or place of organization

FRANCE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 70,470,018.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 70,470,018.00

11

Aggregate amount beneficially owned by each reporting person

70,470,018.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

13

Percent of class represented by amount in Row (11)

42.2 %

14

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person:

(1) Reflects 70,470,018 Common Shares beneficially owned by Atlas Investissement. Iliad Holding, as the controlling shareholder of Atlas Investissement, may be deemed to have shared beneficial ownership over the Common Shares beneficially owned by Atlas Investissement. Maya, as the controlling shareholder of Iliad Holding, may be deemed to have shared beneficial ownership over the Common Shares beneficially owned by Iliad Holding and Atlas Investissement. The Niel Family may be deemed to have shared beneficial ownership over the Common Shares beneficially owned by Atlas Investissement, Iliad Holding and Maya. (2) The percentage reflected in row 13 in the table above is calculated on the basis of 167,083,756 Common Shares outstanding as of July 31, 2025 (169,000,000 Common Shares outstanding, less 1,916,244 Common Shares held in treasury), as set forth in the last relevant update available on the date hereof on the Issuer's website.

SCHEDULE 13D

CUSIP No.

L6388F110

1

Name of reporting person

Elisa Niel

2

Check the appropriate box if a member of a Group (See Instructions)

(a)

(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

Checkbox not checked

6

Citizenship or place of organization

FRANCE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 70,470,018.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 70,470,018.00

11

Aggregate amount beneficially owned by each reporting person

70,470,018.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

13

Percent of class represented by amount in Row (11)

42.2 %

14

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person:

(1) Reflects 70,470,018 Common Shares beneficially owned by Atlas Investissement. Iliad Holding, as the controlling shareholder of Atlas Investissement, may be deemed to have shared beneficial ownership over the Common Shares beneficially owned by Atlas Investissement. Maya, as the controlling shareholder of Iliad Holding, may be deemed to have shared beneficial ownership over the Common Shares beneficially owned by Iliad Holding and Atlas Investissement. The Niel Family may be deemed to have shared beneficial ownership over the Common Shares beneficially owned by Atlas Investissement, Iliad Holding and Maya. (2) The percentage reflected in row 13 in the table above is calculated on the basis of 167,083,756 Common Shares outstanding as of July 31, 2025 (169,000,000 Common Shares outstanding, less 1,916,244 Common Shares held in treasury), as set forth in the last relevant update available on the date hereof on the Issuer's website.

SCHEDULE 13D

CUSIP No.

L6388F110

1

Name of reporting person

Joseph Niel

2

Check the appropriate box if a member of a Group (See Instructions)

(a)

(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

Checkbox not checked

6

Citizenship or place of organization

FRANCE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 70,470,018.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 70,470,018.00

11

Aggregate amount beneficially owned by each reporting person

70,470,018.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

13

Percent of class represented by amount in Row (11)

42.2 %

14

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person:

(1) Reflects 70,470,018 Common Shares beneficially owned by Atlas Investissement. Iliad Holding, as the controlling shareholder of Atlas Investissement, may be deemed to have shared beneficial ownership over the Common Shares beneficially owned by Atlas Investissement. Maya, as the controlling shareholder of Iliad Holding, may be deemed to have shared beneficial ownership over the Common Shares beneficially owned by Iliad Holding and Atlas Investissement. The Niel Family may be deemed to have shared beneficial ownership over the Common Shares beneficially owned by Atlas Investissement, Iliad Holding and Maya. (2) The percentage reflected in row 13 in the table above is calculated on the basis of 167,083,756 Common Shares outstanding as of July 31, 2025 (169,000,000 Common Shares outstanding, less 1,916,244 Common Shares held in treasury), as set forth in the last relevant update available on the date hereof on the Issuer's website.

SCHEDULE 13D

Item 1.

Security and Issuer

(a)

Title of Class of Securities:

Common Shares

(b)

Name of Issuer:

MILLICOM INTERNATIONAL CELLULAR SA

(c)

Address of Issuer's Principal Executive Offices:

148-150, BOULEVARD DE LA PETRUSSE, LUXEMBOURG, LUXEMBOURG , L-2330.

Item 1 Comment:

This Amendment No. 21 ("Amendment No. 21") to Schedule 13D relates to the Common Shares, par value $1.50 per share (the "Common Shares"), of Millicom International Cellular S.A., a Luxembourg company ("Issuer"), and amends and supplements the initial statement on Schedule 13D filed on February 24, 2023, as amended by Amendment No. 1 to the Schedule 13D filed on March 28, 2023, Amendment No. 2 to the Schedule 13D filed on April 26, 2023, Amendment No. 3 to the Schedule 13D filed on May 12, 2023, Amendment No. 4 to the Schedule 13D filed on May 25, 2023, Amendment No. 5 to the Schedule 13D filed on June 2, 2023, Amendment No. 6 to the Schedule 13D filed on July 24, 2023, Amendment No. 7 to the Schedule 13D filed on August 24, 2023, Amendment No. 8 to the Schedule 13D filed on October 2, 2023, Amendment No. 9 to the Schedule 13D filed on November 8, 2023, Amendment No. 10 to the Schedule 13D filed on January 17, 2024, Amendment No. 11 to the Schedule 13D filed on May 23, 2024, Amendment No. 12 to the Schedule 13D filed on July 3, 2024, Amendment No 13. to the Schedule 13D filed on July 22, 2024, Amendment No. 14 to the Schedule 13D filed on August 2, 2024, Amendment No. 15 to the Schedule 13D filed on August 26, 2024, Amendment No. 16 to the Schedule 13D filed on September 9, 2024, Amendment No. 17 to the Schedule 13D filed on October 11, 2024, Amendment No. 18 to the Schedule 13D filed on March 12, 2025, Amendment No. 19 to the Schedule 13D filed on March 17, 2025, and Amendment No. 20 to the Schedule 13D filed on August 13, 2025 (as so amended, the "Schedule 13D"). Capitalized terms used but not defined in this Amendment No. 21 shall have the same meanings ascribed to them in the Schedule 13D.

Item 4.

Purpose of Transaction

Item 4 of the Schedule 13D is hereby amended and supplemented by adding the following: On August 20, 2025, Atlas Investissement entered into European-style call spread option transactions (the "Transactions") with unaffiliated third party financial institutions. The Transactions provide Atlas Investissement with economic exposure to the Common Shares between the lower strike prices and upper strike prices for each respective call thereunder, each in respect of up to 1,111,111 Common Shares, with a premium, strike price and cap price based on pre-determined formulas, which take into account each financial institution's hedging activity (such strike and cap prices, as well as other variables of the Transactions, also subject to adjustments in certain circumstances). The Transactions are exercisable in 40 separate tranches of approximately equal size, with staggered expiration dates on successive trading days (subject to market disruption). The Transactions can be settled in Common Shares or cash subject to certain conditions. The foregoing description of the Transactions is qualified in its entirety by reference to the Letter Agreements on Share Option Transaction, each of which is filed as Exhibit 25, 26 and 27, respectively, to the Schedule 13D and incorporated herein by reference.

Item 5.

Interest in Securities of the Issuer

(a)

See Items 11 and 13 of each of the cover pages.

(b)

See Items 7 through 10 of each of the cover pages.

(c)

Except as described in Item 4 above and in Item 4 of Amendment No. 20 to the Schedule 13D filed on August 13, 2025, the Reporting Persons have not effected any transactions in Shares during the past sixty days.

Item 6.

Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer

Item 6 of the Schedule 13D is hereby amended and supplemented as follows: The information set forth in Item 4 of this Amendment No. 21 is incorporated herein by reference.

Item 7.

Material to be Filed as Exhibits.

Item 7 of the Schedule 13D is hereby amended by adding the following exhibits: 25. Letter Agreement on Share Option Transaction, dated August 20, 2025, by and between Atlas Investissement SAS and Credit Agricole Corporate and Investment Bank. 26. Letter Agreement on Share Option Transaction, dated August 20, 2025, by and between Atlas Investissement SAS and Natixis. 27. Letter Agreement on Share Option Transaction, dated August 20, 2025, by and between Atlas Investissement SAS and Societe Generale.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Atlas Investissement SAS

Signature:	/s/ Anthony Maarek
Name/Title:	Anthony Maarek, Managing Director
Date:	08/22/2025

Iliad Holding SAS

Signature:	/s/ Xavier Niel
Name/Title:	Xavier Niel, President of Maya SAS, itself President of Iliad
Date:	08/22/2025

Maya SAS

Signature:	/s/ Xavier Niel
Name/Title:	Xavier Niel, President
Date:	08/22/2025

Xavier Niel

Signature:	/s/ Xavier Niel
Name/Title:	Xavier Niel
Date:	08/22/2025

Jules Niel

Signature:	/s/ Jules Niel
Name/Title:	Jules Niel
Date:	08/22/2025

John Niel

Signature:	/s/ John Niel
Name/Title:	John Niel
Date:	08/22/2025

Elisa Niel

Signature:	/s/ Xavier Niel
Name/Title:	Xavier Niel, Attorney-in-Fact, for and on behalf of as Parent/Guardian of Elisa Niel
Date:	08/22/2025

Joseph Niel

Signature:	/s/ Xavier Niel
Name/Title:	Xavier Niel, Attorney-in-Fact, for and on behalf of as Parent/Guardian of Joseph Niel
Date:	08/22/2025