6-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATEISSUER

PURSUANT TO RULE 13a-16OR 15d-16 OF THE

SECURITIES EXCHANGE ACTOF 1934

For the month of April, 2025.

Commission File Number: 001-38763

MILLICOM INTERNATIONAL CELLULAR S.A.

(Exact Name of Registrant as Specified in ItsCharter)

8400 NW 36^th^ Street, Suite 530

Doral, FL 33166

United States

(Address of principal executive office)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F:

Form 20-F x Form 40-F ¨

MILLICOM INTERNATIONAL CELLULAR S.A.

INDEX TO FURNISHED MATERIAL

Item

______

Item 1

SEB informs Millicom (Tigo) it has completedthe sale of shares

Luxembourg, April 23, 2025– Millicom International Cellular S.A. (“Millicom”) completed the delisting of its Swedish Depositary Receipts (SDRs) from Nasdaq Stockholm on March 17, 2025, resulting in the Nasdaq Stock Market in the United States being the sole exchange where its common shares are listed.

SEB, the SDR program custodian bank, informed Millicom today that it has completed the sale of approximately 5,110,103 shares underlying the SDRs that had not been withdrawn by the SDR holders prior to the delisting. Net proceeds from the sales are expected to be distributed pro rata to these former SDR holders in early May.

-END-

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About Millicom

Millicom (NASDAQ U.S.: TIGO) is a leading provider of fixed and mobile telecommunications services in Latin America. Through our TIGO^®^ and Tigo Business^®^ brands, we provide a wide range of digital services and products, including TIGO Money for mobile financial services, TIGO Sports for local entertainment, TIGO ONEtv for pay TV, high-speed data, voice, and business-to-business solutions such as cloud and security. As of December 31, 2024, Millicom, including its Honduras Joint Venture, employed approximately 14,000 people and provided mobile and fiber-cable services through its digital highways to more than 46 million customers, with a fiber-cable footprint over 14 million homes passed. Founded in 1990, Millicom International Cellular S.A. is headquartered in Luxembourg, with principal executive offices in Doral, Florida.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

Date: April 25, 2025