The US has mounted a global campaign to rid telecoms networks of equipment made by Huawei, which it accuses of spying. Now, it is tempering its hostility, tweaking rules to let US companies work with the Chinese group in setting standards for 5G networks. The move is belated and any benefits to investors would be limited.

The rapprochement lifted quoted shares in suppliers to privately held Huawei, including NeoPhotonics, Shennan Circuits and Sunny Optical, more than 6 per cent. The stocks of China's three largest telecom operators rose too. But neither these companies nor US telecoms businesses have much to gain.

The US banned Huawei from its domestic market last May. US companies need special licences to deal with the Chinese group. In theory, this should exclude Huawei from technology-related discussions as well as blocking its US revenues.