The S&P 500 Is Too Big to Falter on Trump’s Tariffs

If you’re looking to a popular stock market tracker like the S&P 500 Index to gauge the effect of President Donald Trump’s proposed tariffs, don’t. It’s likely to be insulated from much of the fallout and therefore fail to reflect the true impact on US businesses.

The S&P 500 is synonymous with the US stock market for many people, but it has never been representative of the broad market. It excludes most of the roughly 4,000 US stocks. It also weights its constituents by market value, giving bigger companies more representation in the index than smaller ones. About 100 companies make up roughly 75% of the index by weighting.

But the S&P 500’s reach is even more limited now than usual. Beyond the handful of technology giants that make up nearly a third of the index, market concentration is rising across industries. The winners are amassing market share — and with it more pricing power, which helps when faced with the prospect of a trade war raising input costs.

Procter & Gamble Co., for example, captured 40% of the revenue generated by public companies in the household and personal products industry during the past 12 months, four times the market share of its next biggest competitor. P&G’s dominance should give it more leverage than its rivals to pass on the cost of tariffs to customers. And because P&G’s weighting in the S&P 500 is nearly twice that of the rest of the industry combined, the index will mostly disregard how the broader group fares.

P&G isn’t alone. Amazon.com Inc. captured 38% of the revenue generated by the consumer discretionary distribution and retail industry last year. Microsoft Corp. grabbed 32% of software and services. Berkshire Hathaway Inc. took 28% of financial services, surprisingly, and 24% of banking went to JPMorgan Chase & Co.

S&P 500