South Korea's Ministry of Science and ICT (MSIT) has canceled Stage X's mobile license.
The move to do so is no surprise as it was reported last month that MSIT was preparing to revoke Stage X's license.
MSIT said that Stage X had failed to meet the legal requirements to run its business.
The company is made up of a consortium led by Kakao and includes MVNO Stage Five.
Stage X had been poised to become the country's fourth network operator after it had secured 28GHz of spectrum to operate 5G services in February, and committed to invest KRW430 billion ($311.6m).
It saw off competition for the spectrum from other hopefuls Sejong Telecom and My Mobile Consortium.
It was reported by The Korea Herald last month that Stage X failed to make a payment of KRW205 billion ($149m).
South Korea's mobile market is currently served by SK Telecom, LG U+, and KT Corporation. Stage X was set to launch mobile services from next year.
All three telcos previously lost their access to the 28 GHz license, with SK Telekom losing it last May, while KT Corporation and LG U+ had theirs canceled in 2022.
