Singtel shares fell 1.7% on Wednesday after Singapore’s telecommunications regulator fined the group S$1 million over mobile service disruptions in March that affected around 720,000 subscribers.

The Infocomm Media Development Authority said the outages on March 16, 18 and 19 were preventable, citing cooling system failures, inadequate monitoring and technical issues following network traffic rerouting. The regulator ruled out a cyberattack.

Singtel has since strengthened its network monitoring and maintenance procedures. It also provided about S$8 million in goodwill rebates to affected customers.

The penalty adds to scrutiny of network reliability across the group, as its Australian subsidiary Optus has also faced criticism over service disruptions. The latest development may weigh on investor sentiment amid concerns over operational risks and service reliability.