S&P 500 HITS RECORD HIGH AS MOST CONSTITUENT STOCKS DECLINE

The S&P 500 climbed to a new all-time high on Tuesday. Market watchers, including Jim Cramer, said the advance has relied on a small number of large stocks rather than broad gains across the index. FactSet figures show about three-quarters of the index's 500 companies were trading lower between 13 August, the date of the previous record, and Monday's close. The S&P 500 Equal Weight Index, which weights all 500 constituents equally rather than by size, has fallen almost 5% over that period. The standard, market capitalisation-weighted index rose by about 1% over the same stretch.

The gap reflects how the index is built: a handful of trillion-dollar companies, including the "Magnificent Seven" group plus AMD and Micron Technology, can move the whole market-value-weighted index regardless of other stocks. Mid-August told a different story, when both the standard index and the Equal Weight Index closed at records on the same day. Those figures show the Equal Weight Index gained 16% from the start of the year to that point, ahead of the standard index's 14% rise. The Equal Weight Index has not beaten the standard S&P 500 over a full year since 2022, a period market commentators link to the start of the generative artificial intelligence boom.

Market participation broadened in the sessions just before Tuesday's record, which commentators said was worth watching for signs it continues. Separate reporting said government bonds rallied and oil prices fell, easing concerns about inflation. Other reports said OpenAI was in talks with BlackRock and investment funds from the United Arab Emirates over a $30 billion financing round. Reports linked the financing talks to the same day's wider market news.