Monday’s sell-off is testing whether investors are simply de-risking or beginning to rotate within the S&P 500 as higher Treasury yields and surging oil prices reshape the macro backdrop.

The Nasdaq 100 fell 1.6% intraday Monday as U.S. Treasury yields hit fresh multi-year highs and oil approached $100, highlighted the Kobeissi Letter in a post on X. The S&P 500 had erased nearly $700 billion in market capitalization during the session.

The pressure comes as Brent crude jumped 4% to $108.50 a barrel Monday, taking its September gain to about 20%. Markets were also pricing a 68% chance of another Federal Reserve rate hike in October, according to Reuters.

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SPY Vs. RSP Could Reveal the Real Sell-off

For ETF investors, the key question is whether the weakness is concentrated among the S&P 500’s largest companies or spreading across the broader index.

The SPDR S&P 500 ETF Trust (NYSE:SPY) provides market-cap-weighted exposure, meaning its performance is heavily influenced by mega-cap stocks. The Invesco S&P 500 Equal Weight ETF (NYSE:RSP) gives each constituent roughly equal weight.

That makes the SPY/RSP relationship an important gauge of market breadth. Recent market analysis noted that the equal-weight S&P 500 was down roughly 4% for September, with nine of 11 sectors negative, suggesting the weakness has extended beyond a handful of mega-cap names.

Growth vs. Value, Energy vs. Defensives

The macro shock is also creating divergent sector exposure.

Higher yields can pressure growth-oriented ETFs such as Vanguard Morningstar Growth ETF (NYSE:VUG), while higher crude prices directly benefit energy companies represented by State Street Energy Select Sector SPDR ETF (NYSE:XLE). Value-focused Vanguard Morningstar Value ETF (NYSE:VTV) has greater exposure to sectors such as financials, industrials and energy, offering a different sensitivity to the current environment.

Meanwhile, defensive ETFs such as State Street Utilities Select Sector SPDR ETF (NYSE:XLU) and State Street Consumer Staples Sel Sect SPDR ETF (NYSE:XLP) could become more relevant if investors prioritize sectors perceived as less economically sensitive.

The bigger ETF story, therefore, isn’t simply that stocks are falling. It’s whether $700 billion of lost S&P 500 value marks the beginning of a broader rotation away from the market’s growth-heavy leadership toward value, energy and defensive exposures.

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