Amazon has announced plans to invest $200bn (£147.7bn) in artificial intelligence (AI) and infrastructure, becoming the latest US tech giant to set out a sharp rise in spending.

It dwarfs the $125bn Amazon spent on AI last year, and appeared to rattle investors. Shares were down nearly 9% in morning trade on Friday, after the company revealed its plans.

This week Big Tech's major players - Amazon, Meta, Google, and Microsoft - collectively announced they will this year plough $650bn into AI and related projects

However, some high profile names in finance and technology have warned that AI is at risk of becoming a bubble which could burst.

As Amazon,which was founded by Jeff Bezos in 1994, set out its full-year results on Thursday, it said it will invest in "AI, chips, robotics and low earth orbit satellites".

Amazon's chief executive, Andy Jassy, was clear on a call with financial analysts that the bulk of its spending will go towards AI. "It's an unusual opportunity," Jassy said of AI, suggesting it will become profitable in the future.

"I passionately believe every customer experience we have today will be reinvented by AI. We're going to invest aggressively," Jassy added.

However, investors are concerned about the scale of spending on AI and when companies will start to see a return.

Like Amazon, the likes of Meta and Microsoft also saw their share prices fall this week, dragging down the wider market.

Mary Therese Barton, chief investment officer at Pictet Asset Management, told the BBC there were "certainly jitters".

She said: "It has definitely been a bit of a rupture and a bit of a wake up call as well, in terms of 'are these investments in AI going to come good?'."

Late last year, the Bank of England warned that major tech firms could face a "sharp correction" in their valuations, saying share prices in the US are reminiscent of those before the dotcom bubble burst in the early 2000s.

The boss of US tech giant Cisco told the BBC that the transition to AI will create winners, but warned there will be "carnage along the way".

Chuck Robbins said the technology will be "bigger than the internet", but the current market is probably a bubble and some companies "won't make it".

And Jamie Dimon, boss of one of America's biggest banks, JPMorgan Chase, said some of the money invested in AI would "probably be lost".

Brian Olsavsky, Amazon's chief financial officer, noted that the company was looking at cost reductions elsewhere as it ramps up spending.

Last week, Amazon laid off another 16,000 workers after cutting 14,000 roles in October.

Leaders of other companies joining the AI rush have struck a similar tone.

Meta boss Mark Zuckerberg said in January the company will spend up to $135bn this year, nearly double last year's amount.

The Facebook, Instagram and WhatsApp owner is working on training its AI models, building out data centres and buying the computer chips that are required to operate AI tools.

But Zuckerberg also pointed to the use of AI by technical workers, saying that fewer people are now needed on big projects.

He predicted "2026 to be the year that AI dramatically changes the way we work."

Google chief executive Sundar Pichai said his firm will invest even more than Meta on AI, more than doubling its capital expenditure to $185bn this year. The company is expanding its technical infrastructure related to AI, including servers and data centres.

While Microsoft did not say exactly how much it will spend over the year, it has so far spent over $72bn on recruiting talent and infrastructure related to AI, while executives have made no mention of pulling back spending.

The S&P 500 stock index, which hit an all-time high at the end of January, fell by more than 1% on Thursday, its third day in a row of losses. The index was up almost 1% in morning trade on Friday.