A planned $600 billion artificial intelligence spending splurge by big tech firms in 2026 is adding to investor unease as they assess the implications for profitability as well as a potential existential threat to software firms.

Amazon, which said its capital expenditure could double from a year ago, fell sharply in pre-market trading on Friday, while shares in other big tech companies rose and Wall Street stock futures firmed.

Meanwhile, shares in data analytics firms continued to come under selling pressure on concerns that they face an existential threat from powerful new AI models.

London-listed RELX’s shares were down 4.8% and set for a 17% tumble in their worst week since 2020, while the S&P 500 software and services index has fallen almost 10% this week and India’s IT index has shed around 7%.

Alphabet and Amazon, members of the so-called Magnificent 7 group of the largest US companies, revealed plans this week to spend much more than anticipated on AI infrastructure.

Although analysts said the stock market selloff has been overdone, investors remain cautious.

Carlota Estragues Lopez, equity strategist at St James’s Place in London said, “It’s not just return on investment that worries investors, but also the risk of narrow market leadership that struggles to broaden beyond a handful of mega-cap names.”

A selloff in software and data and analytics firms was triggered by a new plug-in from Anthropic’s Claude.

Shares in London Stock Exchange Group clawed back some ground on Friday, but the price was still down almost 6% for the week in a second straight week of sharp losses. This week’s drawdown in AI-exposed shares has weighed on broader equity markets. Global shares are on track for the worst week since November, down 1.6%.

The broad S&P 500 index is off 2%, while US software and data services companies have seen around $1 trillion in market value evaporate since January 28.

Investor nerves over potential AI?driven disruption are coinciding with a growing tendency to punish big tech firms for signalling even heavier spending on the technology.