News that MTN Group is facing an investigation by a US department of justice grand jury sent its shares tumbling 9% on Monday, overshadowing results showing it made a half-year profit following a loss a year earlier.

The probe is into its conduct and that of its former subsidiary in Afghanistan and an Iranian cellphone carrier it partly owns. This development, and a slight downward revision of its medium-term service revenue outlook for its South African operation, sent its shares tumbling.

Group CEO Ralph Mupita said MTN had been informed by its external US counsel of the DoJ grand jury investigation, adding that it was cooperating and voluntarily responding to requests for information. Mupita declined further comment on the case.

MTN faces other ongoing legal cases in the US filed on behalf of American service members and civilians who were injured or killed in Iraq and Afghanistan between 2005 and 2010 who accuse it of violating the US Anti-Terrorism Act.

“The plaintiffs’ complaints allege that MTN supported anti-American militias in Iraq and Afghanistan through its participation in Irancell,” the company said in a statement. MTN owns 49% of Irancell.

“Jurisdictional discovery in the cases, ordered in July 2023, has now closed and the plaintiffs filed an amended complaint on 6 August 2025,” the company said. “The amended complaint now includes additional claims against MTN, which are similar to those asserted in the three other pending ATA (US Anti-Terrorism Act) cases in which MTN is involved. MTN will file a motion to dismiss the amended complaint.”

Shares fall

MTN shares fell as much as 9% before closing down 8.4%.

“The shares have done very well coming into these results so part of the selloff could also be profit taking by short-term investors given the US investigations could be an overhang,” said Peter Takaendesa, chief investment officer at Mergence Investment Managers.

MTN is also facing challenges in growing service revenue in its home market due to pricing pressures, intense competition and weak consumer spending. Based on assumptions regarding market conditions and outlook in South Africa, it revised its medium-term guidance for service revenue growth in South Africa to low to mid-single digits from mid-single digits.

It reported headline earnings per share of R6.45 in the six months to 30 June, compared to a headline loss of R2.56 a year earlier, as macroeconomic conditions, inflation and foreign exchange rates in Nigeria and Ghana showed improved stability.