Firmus to invest $300m in SubCo's upcoming Australia-US subsea cable

Australian AI cloud firm Firmus will invest US$300 million to secure up to 150Tbps of dedicated capacity over 25 years on SubCo's upcoming APX East submarine cable system, the companies announced this week. The deal makes Firmus a cornerstone customer on the cable, which is being developed by SubCo, the company founded and co-led by Bevan Slattery.

APX East is a 16-fiber-pair system set to connect Australia to the United States, running from the north of Sydney in New South Wales to San Diego, California. The cable's Australian landing station will be at NextDC's S1/S2 site in Sydney. APX East is expected to be Ready for Service in Q4 2028, with a Hawaii branch to follow in Q4 2029 and a Fiji branch also planned. SubCo has previously said the system will be the first between Australia and the United States not requiring optical regeneration, instead capable of being single-end powered across the entire system, making it the longest such system in the world.

Firmus co-CEO and co-founder Tim Rosenfield framed the investment as a 25-year commitment to Australia's AI infrastructure. "AI is fast becoming one of Australia's next major export industries, but that opportunity will only be realized if we invest in the infrastructure that underpins it," he said. Firmus, founded in 2019 and backed by Nvidia, describes itself as a pure 'AI factory' builder and is targeting some 1.6GW of infrastructure by 2028. The dedicated capacity is intended to connect Australian AI infrastructure directly with the United States, supporting the company's network of AI Factories across Australia.

The announcement does not specify the total cost of the APX East system, the ownership structure beyond Firmus's capacity commitment, or how the investment will be financed. It also remains unclear whether the Q4 2028 Ready for Service date is contingent on additional anchor customers or regulatory approvals. The source, Data Center Dynamics, is a secondary trade publication, and the details have not yet been corroborated by primary filings or independent reporting.