China’s AI-stock boom loses $480bn as the STAR50 falls 40%

China’s technology-heavy STAR50 index has fallen about 40% in less than four months, wiping roughly US$480 billion from its market value. The sell-off is a sharp reversal in an AI investment boom, even as Chinese chipmakers are becoming more serious competitors to Nvidia.

Watch Desk analysis

What happened

Coinpaper reports that Reuters traced the downturn to questions about AI demand, corporate profitability and the high valuations of Chinese semiconductor and robotics companies. The broader CSI 300 has also fallen about 20% from its June peak, putting it in bear-market territory.

At the boom’s height, AI-related shares made up about 42% of Chinese equity-market capitalisation and 57% of trading turnover, according to Goldman Sachs data cited by Reuters. Coinpaper also says Reuters reported Nvidia’s share of China’s data-centre AI accelerator market fell to 34% in the first half of 2026, with shipments down 44% year on year. Export controls and Beijing’s support for domestic alternatives are part of that competitive picture.

Why it matters

This is a bruising market reset, not evidence that AI infrastructure spending has stopped or that China’s AI ambitions have evaporated. A market-value loss is not the same as US$480 billion in cash disappearing from companies. But weaker valuations can make it harder for firms to raise money for costly chip development and computing expansion.

There is an awkward split-screen here: investors are marking down Chinese AI companies while domestic suppliers are gaining ground in a strategically important market. A retreat in share prices and a stronger competitive challenge to Nvidia can happen at the same time.

Our read

The fall is a useful warning against treating soaring AI valuations as proof of durable commercial returns. It is not, on its own, a verdict on the technology or the competitive prospects of Chinese firms. The more revealing numbers now will be sales, deployments and funding, not another dramatic chart with a large red arrow.

What to watch

• Whether China’s AI and semiconductor valuations keep falling, or find a floor.
• How domestic suppliers’ accelerator shipments and market share develop.
• Whether tighter valuations affect companies’ ability to fund new chips and computing capacity.

Discussion spark: If Chinese AI firms gain ground against Nvidia while their shares plunge, should we read that as a market correction or a warning that the industry’s growth story is overstated?

Watch Desk is operated by WittyWires as an independent cross-cutting AI news tracker. It does not speak for the organisations or people it covers.