Let the wild rumpus start: is the US facing a stock market ‘super-bubble’?

The tech sector led US stock markets on a pandemic boom last year. Now markets are whipsawing on fears that the Federal Reserve will end the era of easy money, all while a potential war in Ukraine looms. Some warn of a bigger correction to come on a scale not seen since the dotcom collapse of the late 1990s.

On Monday, US stock markets crashed then rallied. The Dow Jones at one point lost more than 1,000 points before ending up just over 100. Tuesday was more of the same with the Dow losing 800 points only to gain most of it back. Analysts expect more volatile days ahead. The Fed on Wednesday issued its latest update on its plans to raise rates in order to curb inflation, and the world's largest tech firms are preparing to issue their latest results to investors, who appear to have grown more skeptical about their prospects.

Jeremy Grantham, the British co-founder of Boston-based investment manager GMO, believes the US is now in a "super-bubble" comparable to the dotcom era, the Wall Street crash of 1929, and the housing market madness of 2006. It is not just tech that has blown up, but housing prices, commodities and bond prices.

The "wild rumpus" has begun, according to Grantham. It is unlikely to end soon.

The latest test of investor resolve came on Tuesday when Microsoft released its quarterly results. The Seattle-based tech giant announced sales topping half a billion a day and a profit of more than $18bn. Huge numbers, and better than expected. Its shares initially fell 5% in after-hours trading.

Microsoft will be followed by Apple, Tesla, Intel and Samsung this week, with more to come from Alphabet, Amazon and Meta next month - a litmus test for a newly acid view on a sector that now dominates the stock markets and much of daily life.

Already one of the pandemic's winners has shown how much the mood has changed. Netflix, which boomed during the pandemic lockdowns, saw its share price collapse after a disappointing earnings result last week that predicted a slowdown in subscribers.

For Brian Wieser, president of business intelligence at GroupM Global, Netflix's woes may have been the catalyst that changed investor confidence in the sector. "Investors generally need a catalyst for an action," he said. The rising cost of capital has worried investors that the days of heady growth are over.

But this isn't a repeat of the dotcom bubble, he said. Today's tech titans are sitting on huge piles of cash and are still making big profits. "Netflix is still going to spend $20bn on content this year," he said. Apple has more than $195bn in cash, and Microsoft has another $130bn.

The vertiginous swings markets are experiencing are partly down to today's "hyper-connected" world, according to Michael Antonelli, managing director at Robert W Baird. "Markets, data, sentiment, trading, podcasts, blogs: everybody knows everything instantly and they can act on any emotion with the push of a button."

Today's losses are somebody's future gains, he noted in a blogpost. But added: "Humans are irrational creatures; they aren't going to take the time to think about their actions when they can push a button and quiet the pain receptor in their brain."