Shares in ASX-listed telecommunications company Tuas plunged on Monday 26 October after it disclosed that its Singapore mobile operator, Simba Telecom, had been served a show cause notice by Singapore’s Infocomm Media Development Authority (IMDA). The Straits Times reported the shares fell more than 33% after the open, trading at A$1.21 at 9.50am against a previous close of A$1.81. ACB News reported the shares ended the day down about 30.5%.
The allegations
According to The Straits Times, the fresh allegations include that Simba deployed dynamic spectrum-sharing at about 133 sites for intermittent periods in 2022 and 2023, using its 2,100 MHz band for both 4G and 5G when it was authorised to use it only for 5G, and that it used the 2,340 MHz to 2,360 MHz band without authorisation at about 92 sites between 2023 and 2026. The regulator alleges these instances were intentional and approved by senior management.
Other allegations include the unauthorised deployment of 5G equipment at two locations in 2023 and a failure to comply with a production order, which the regulator said raised concerns about deficiencies in Simba’s governance and compliance culture. These are allegations only. IMDA said Simba “will have the opportunity to respond to IMDA’s findings” and that the investigation remains ongoing.
What is at stake
Simba must respond by 16 November. The Straits Times reported that possible outcomes include suspension or cancellation of spectrum rights, a fine of up to S$1 million or 10% of Simba’s annual Singapore revenue, whichever is higher, and suspension, cancellation or shortening of its telco licence. Tuas said Simba intends to respond by the deadline.
“As the matter remains under consideration by the regulator and no findings have been made or confirmed, Tuas does not intend to provide further comment on the matters raised in this announcement,” Tuas said in its ASX filing.
The backstory
The investigation became public in May, when IMDA suspended its review of Simba’s S$1.43 billion bid for M1’s telecommunications business over the spectrum issue, and the deal later collapsed. In September, Simba admitted it had used spectrum beyond its permitted limits, attributing the 2,300 MHz usage to a combination of hardware and software issues.
The lesson
For investors, the episode shows how a regulatory problem in a single offshore market can reshape the value of an ASX-listed growth company overnight, particularly when the regulator’s concerns extend from the conduct itself to governance and cooperation with its inquiries.
Sources: The Straits Times (26 October 2026); Tuas ASX announcement (26 October 2026); ACB News (2 November 2026).