Growing uncertainty about when OpenAI will go public is heaping pressure on SoftBank's looming listing of SB Energy, its US data centre developer that has yet to bring a single facility online. The IPO, which could happen in the coming weeks at a target valuation around $50bn, is set to test investor willingness to keep backing founder Masayoshi Son's bet as he tightens his entanglement with the two companies at the heart of AI. Both OpenAI and chipmaker Nvidia will own significant stakes in a listed SB Energy.

OpenAI has delayed its own IPO and is in early talks for a private funding round that could value it at $1.2tn. The moves added uncertainty to SoftBank, which has committed more than $60bn to the ChatGPT maker, as it sought to bankroll Son's desire to spend heavily on new AI ventures next year. SB Energy's aim is to build data centres, connect them to electricity grids and in some cases provide power.

It has a backlog of contracts worth $439bn in future revenue, with the vast majority related to 8.8 gigawatts of data centre capacity. However, SB Energy has no data centres in operation, helping explain why $357bn of the future contracted revenue is only expected to be recognised from 2034 onwards. The group's main development will be a campus in Ohio that is expected to deliver 8GW of new capacity by 2032.

Nvidia has agreed to provide a guarantee of $105bn for the Ohio project's initial phase. OpenAI will be the tenant on the campus, as well as on an SB Energy site in Texas. SB Energy has acknowledged the potential perils of its dependence on its interlinked main backers, particularly its exposure to any shifts in OpenAI's strategy.