Investing.com -- The S&P 500 IT sector fell 5.5% on Monday, marking the largest single-day decline in that index since 2020.
The drop was primarily concentrated in companies that had been expected to play a crucial role in facilitating AI, including semiconductor and utilities firms behind data centers. But the broader S&P 500 index only dipped by 1.5%, which was not the most substantial drop this month, and around 70% of the firms within the index actually saw their shares rise.
“We think it's too soon to say whether this is the start of a slump for those large US firms which have benefited most from Al hype until now - but if it was, what would it mean for the S&P 500?” James Reilly, Senior Markets Economist at Capital Economics asked.
“Our sense is that the index would slip this year, but that the average stock in that index could hold up well,” he added.
Reilly suggests that there may be a shift in investor focus from these 'enablers' to the 'users' of AI technology, mirroring a similar rotation within the IT sector during the dot-com bubble around 1999/2000. This rotation did not hinder the overall performance of the S&P 500 at the time.
“After all, the latest developments haven't called into question Al's status as a transformative technology; rather, they have primarily sparked debate over who stands to benefit most from enabling the Al revolution,” Reilly said.
In this scenario, the S&P 500 could continue to rally despite waning sentiment toward these former favorites.
Capital Economics also drew parallels to the dot-com bubble's burst in 2000, where the average stock in the S&P 500, represented by an equal-weighted index, remained relatively stable until the onset of a US recession.
This historical perspective indicates that the average firm in the S&P 500 could continue to perform well if the economic backdrop remains positive, despite potential unwinding in the valuations and earnings expectations of 'big-tech' firms heavily involved in AI.
The recent market rally has been particularly concentrated among the largest firms within the S&P 500. The top 100 firms have a similar weight as they did in 2000, but the top 10 firms now have a larger share than ever.
“That might mean that the losses as these gains unwound would be similarly concentrated, affording plenty of scope for the average firm in the S&P 500 to do well if the economic backdrop stayed positive, as we expect,” Reilly explained.
In other words, the economist argues that if the AI rally were to end, it could drag down the market-cap weighted S&P 500, similar to the events of 2000. However, this may not necessarily topple the average firm within the index.