Nearly Half of S&P 500 Stocks Moved Against the Index in Three-Month Measure
About 45% of constituents showed negative three-month beta as mega-cap technology companies and AI infrastructure beneficiaries helped drive benchmark gains.
Nearly half of S&P 500 stocks showed negative three-month beta against the index, revealing a divergence between benchmark gains and broader market participation for U.S. investors.
About 45% of constituents had negative three-month beta, meaning their returns generally moved opposite the S&P 500 during the measurement period. A separate calculation based on weekly returns found nearly 40% had negative three-month beta and 17% had negative one-year beta.
Negative beta describes a statistical relationship over a specified period. It does not mean a stock will consistently rise whenever the index falls.
The divergence reflects the S&P 500’s float-adjusted market-capitalization weighting, which gives larger companies a greater influence on the benchmark. The index’s concentration in mega-cap technology companies and AI infrastructure beneficiaries helped drive gains even as lower-weighted constituents weakened.
The S&P 500 rose 1.5% in one session while 30 constituents reached 52-week lows and seven reached new 52-week highs.
“It only takes a few of those mega caps names to work, and a lot of the smaller weighted stocks don’t need to work,” said Adam Turnquist, chief technical strategist at LPL Financial.
AI infrastructure companies have been among the main drivers of market gains, while the group of stocks with negative beta was tilted toward energy, utilities and consumer staples. AI investment appeared on 67% of S&P 500 earnings calls in the second quarter.
“Beta is a function of correlation and volatility,” said Bradley Krom, director of investing strategy at WisdomTree. Kurt Feuerman, chief investment officer of Select U.S. Equity Portfolios at AllianceBernstein, said, “But a narrow market can also distort the signal investors receive from index returns.”
The differing negative-beta figures reflect separate measurement periods and calculations, so they describe different views of market participation rather than a single unified count.
