A record that flatters the index
The aggregate profit margin for the S&P 500 reached its highest level on record in Q2. On the surface, that looks like broad-based corporate strength. Dig into the components, though, and the picture narrows fast.
One company accounts for a disproportionate share of the margin expansion. Without that single contributor, the index's margin wouldn't look nearly as strong. The record is real, but it's a record carried by one name rather than a wave of profit growth across the board.
That's how a market-cap-weighted index works. The biggest constituents move the aggregate numbers far more than the hundreds of smaller companies in the index. So a record-high margin for the S&P 500 doesn't mean the typical member is enjoying the same tailwind. It means the heaviest weight in the basket is pulling the whole thing up.
