Australia's Competition Tribunal (ACT) last week blocked an asset transfer deal between telco firms Telstra Group and TPG Telecom.
The duo confirmed the ACT, which is the country's federal court, upheld the decision by the Australian Competition and Consumer Commission (ACCC) decision not to grant authorization for the proposed regional spectrum authorization arrangements.
Following the decision, TPG shares fell by as much as 11 percent last week.
The deal which was first announced last year, would have seen Telstra buy spectrum and transmission towers from TPG, while TPG would have kept selling 4G and 5G coverage using Telstra infrastructure.
However, regulators in the country moved to block the deal as it was seen to be anti-competitive. The tribunal agreed, and noted that the proposed arrangements would give Telstra substantial benefits and increase its market strength while hurting Optus' incentives to invest in 5G.
The deal would have seen Telstra gain access to 169 TPG sites.
ACCC Commissioner Liza Carver said in December that the agreement would distort competition.
"While there are some benefits, it is our view that the proposed arrangements will likely lead to less competition in the longer term and leave Australian mobile users worse off over time, in terms of price and regional coverage,” said Carver last year.
Optus, a rival operator to Telstra and TPG in Australia has welcomed the verdict.
Telstra and TPG are considering a further appeal, according to reports.
"At the moment, we're limited in the amount of spectrum we can buy at auction and, as today's result shows, limited in the type of commercial arrangements we can put in place to improve services for our customers," Telstra CEO Vicki Brady said.