The rally in US chip stocks that has seen Nvidia and AMD more than double in value over the past year is under pressure after warnings that the artificial intelligence boom is masking a broader slump in semiconductor demand.

The Philadelphia Stock Exchange Semiconductor Index, which tracks the 30 top US chip companies, has risen by more than 50 per cent in 12 months as investors bet on continued soaring demand for the AI processors that power OpenAI’s ChatGPT and similar apps.

But only a handful of companies have benefited significantly from the insatiable demand for AI chips among Big Tech companies and start-ups such as OpenAI and Anthropic over the past year. Nvidia and its suppliers, including TSMC and Supermicro, have enjoyed disproportionate gains, while most other chipmakers grapple with stockpiled inventories and damp customer demand across a range of industries.