The S&P 500 fell on chips. The average stock in it rose
Monday, September 14: Invesco's S&P 500 equal-weight fund RSP rose 0.07% as State Street's cap-weighted S&P 500 fund SPY fell 0.45%; 2,592 U.S. stocks advanced and 2,952 declined.
Anthropic chief executive Dario Amodei published a Saturday essay arguing the industry should slow how fast it improves model capabilities. OpenAI's Sam Altman and Elon Musk posted their agreement; Altman, in an interview published the same day, also called a 2026 public listing ill-advised. South Korea's Kospi, heavy with chip suppliers, had already dropped 3.26% in Monday's Asia session before New York opened.
Nvidia then subtracted 0.27 percentage points from SPY at Monday's close, about 60% of the decline. Broadcom, Micron and Advanced Micro Devices brought the four-stock hole to 0.54 percentage points, more than the fund fell, which means the rest of the portfolio was a net plus. Thirteen of 20 mega-caps finished higher.
Micron is now 4.9% of the Nasdaq-100 fund QQQ, large enough that a 5.25% drop subtracted 0.26 percentage points on its own, almost matching Nvidia's 0.28-percentage-point hit.
Nvidia, Broadcom, Micron and AMD
In QQQ's top 11, chips fell and the platforms rose
- +3.2%
- +3.1%
- +2.7%
- +2.0%
- +0.2%
- −1.3%
- −1.8%
- −3.4%
- −4.4%
- −4.8%
- −5.3%
VanEck's semiconductor fund SMH lost 4.75%, extending a one-month decline of 8.1%. Oracle, which is not a chipmaker but sits in the same AI-infrastructure complex, fell 3.70%.
The same split ran through the Nasdaq-100. QQQ fell 0.80% while First Trust's equal-weight Nasdaq-100 fund QQEW rose 0.14%. Software moved the other way: Palo Alto Networks jumped 13.1% and CrowdStrike 13.9%, adding 0.16 and 0.13 percentage points to QQQ. It was not enough.
Among the 20 largest names, Eli Lilly rose 1.98% and Netflix 3.77%; the seven that fell were Nvidia, Amazon, Broadcom, Tesla, JPMorgan Chase, Oracle and Exxon Mobil. The communication services sector fund XLC gained 2.19%, health care XLV 1.45%, and consumer staples XLP 1.25%. The technology sector fund XLK fell 1.81%. Three of the eleven Select Sector funds finished up.
RSP holds 17.3% in technology against 38.7% in SPY. A semiconductor decline of this size shows up in the cap-weighted fund and barely registers, name by name, in equal weight.
2,952 decliners against 2,592 advancers
Across 5,809 U.S. common stocks listed on the NYSE, Nasdaq and NYSE American (ETFs, funds, foreign listings, FX and crypto symbols excluded), decliners led: 2,952 down, 2,592 up, 265 unchanged. Advancers were 44.6% of that list. IWM fell 0.35%.
The average S&P 500 stock rose a fraction. The typical U.S. stock did not.
Equal-weight still trails over a month
Monday inverted a pattern that had been running the other way.
Equal-weight still trails the cap-weighted S&P 500
- −5.1%
- −3.5%
- −3.1%
- −2.2%
RSP is still ahead year to date, up 13.2% against 12.2% for SPY. IWM leads both, up 17.5%. The one-month giveback in equal-weight and small-caps is a pullback inside that 2026 lead, not a new ranking.
Frequently asked
Why did the S&P 500 fall if most of its big names rose?
Nvidia, Broadcom, Micron and AMD together subtracted more than the index fell, so the rest of the portfolio was a net plus.
What set off the chip selling?
Anthropic's chief executive published an essay arguing the industry should slow how fast it improves model capabilities, and OpenAI's Sam Altman and Elon Musk agreed; Korea's chip-heavy Kospi had already dropped before New York opened.
Did anything go up?
Communication services, health care and consumer staples sector funds all gained, and Palo Alto Networks and CrowdStrike each jumped more than 13%.
Does this mean equal weight is now beating cap weight?
Not over the past month: equal weight and small caps both trail the cap-weighted S&P 500 there, though both are still ahead year to date.