Stock soar after NVIDIA's earnings defy fears of an AI bubble.

Live from the UK, this is the Marketplace Morning Report from the BBC World Service.

I'm William Lee Adams. Good morning.

Global shares received a boost today, cheered by better than expected results from U.S. chip giant

NVIDIA. But despite the optimism, the artificial intelligence boom continues to spark fears of a market bubble.

A growing number of the world's leading figures in finance have suggested that AI stocks are

unrealistically inflated in value.

The BBC's Ed Butler's been looking at the issue.

History tells us this sentiment can turn on the dime. That's Kristallina

George Ava, head of the IMF, one of the biggest figures in international finance. Even leading Silicon

Valley investors like Jerry Kaplan are now weighing in. We're in the middle of an enormous economic bubble.

What we're seeing is this process of this thing feeding on itself,

and when it collapses, it's going to be very bad.

As everyone in Silicon Valley remembers, we have been here before.

The internet appliance provider got hammered today, losing over 10 points

after Bear Stearns issued some cautious comments on the stock.

Technology stocks got trounced on the day of...

Some of the new economy.coms are sinking as fast as the level of the tide on the Thames.

This was March 2000, when many of the first generation of heavily backed internet firms were swamped in an avalanche of red as investors lost faith.

Five trillion dollars were wiped off the US Tech Index over two years as shares crumbled.

Professor of Finance, John Danielson at the London School of Economics,

has made a career out of studying economic bubbles.

...