The S&P 500's drop understated a broad decline

The S&P 500 closed at 7,674.13, down 0.58%, in the first session after the Labor Day weekend. Counted stock by stock, Tuesday was a broad decline that the cap-weighted print only partly showed. No single name produced the move. The only place leadership showed up was a handful of semiconductors inside the Nasdaq-100.

3,638 stocks fell on a 5,843-name board

Of 5,843 U.S. common stocks listed on the NYSE, Nasdaq and NYSE American (ETFs, other funds, foreign listings, and currency and crypto symbols excluded), 1,998 advanced, 3,638 declined, and 207 were unchanged. Advancers were 34% of the board.

That is the opposite split from Friday, when the S&P 500 fund fell and a slight majority of U.S. stocks still rose. Fifteen of the 20 largest names fell, including Nvidia, Apple, Microsoft, Eli Lilly and JPMorgan Chase. Five of those 20 rose.

Equal-weight lost more than the S&P 500

The S&P 500 fund ASPY fell 0.55%. The S&P 500 equal-weight fund BRSP, which holds the same companies at the same size, fell 1.04%, nearly twice as much. Equal-weight lagged cap-weight by 0.49 percentage points. The extra loss sat inside the S&P 500 itself, once every name counted the same.

Small-cap stocks, through the Russell 2000 fund AIWM, fell 0.45%, in line with cap-weighted large-caps. The weak sleeve was not size. It was the typical large-cap.

Health care is 13.1% of the equal-weight fund and 9.3% of ASPY. The health-care sector fund AXLV fell 2.5%. Amgen dropped 10% after Novartis reported disappointing trial results in a cholesterol-drug class both companies work in, and it was the largest hole in the equal-weight fund. Eli Lilly and Johnson & Johnson each fell 2.2%. Energy went the other way. Brent crude traded as high as $99.45 a barrel overnight after attacks on Saudi energy facilities. The energy sector fund AXLE rose 1.1%, and Exxon Mobil gained 0.7%. One strong sector did not offset a session in which most of the index was under pressure.

One day is weather. Over the past month BRSP is down 1.5%, against a 0.9% decline in ASPY. Tuesday extended that stretch.

Intel and AMD held the Nasdaq-100 near unchanged

The Nasdaq-100 fund AQQQ fell 0.08%. Intel rose 9.1% on reports it planned another increase in processor prices and added 0.19 percentage points to AQQQ. AMD rose 5.9% and added 0.20 percentage points. Tesla gained 4.0% and Broadcom 3.0%. Those four more than offset Nvidia's 2.0% decline, which subtracted 0.18 percentage points from the Nasdaq-100 fund and 0.17 from ASPY, the largest single hole in the S&P 500 fund.

In ASPY, though, the eight biggest contributors and detractors together accounted for only about 15% of the fund's decline. The other ~496 names produced the move.

Tomorrow would have to look different on both measures. Advancers would need a majority on the same 5,843-stock board, and BRSP would need to match or beat ASPY. Equal-weight remains ahead for 2026, up 14.1% against 12.9% for the cap-weighted fund.