The US stock market's bull run is approaching its fourth anniversary, underpinned by strong corporate earnings and unusually low volatility. Yet as benchmark indices continue to climb, investor unease is growing over a persistent disparity between the performance of the indexes and that of individual stocks — a narrowing of market leadership that is increasingly viewed as a risk, according to an Economic Times Markets report published on October 9, 2026.

The current bull market traces its origins to October 2022, when the S&P 500 bottomed after the Federal Reserve's most aggressive interest-rate-hiking cycle in decades pushed the index into a bear market that erased roughly a quarter of its value. The benchmark notched its closing low on October 12, 2022, and has since delivered consecutive years of substantial gains, rising more than 20% in both 2023 and 2024 — its first back-to-back annual advances of that magnitude since the late 1990s.

Since that low, the recovery has been propelled disproportionately by a small group of mega-capitalization technology companies whose fortunes are closely tied to artificial intelligence, including NVIDIA, Microsoft, Alphabet, Amazon and Meta Platforms — a cluster widely known on Wall Street as the "Magnificent Seven," a label that in its fullest definition also encompasses Apple and Tesla. The concentration of gains in so few names has become a defining and frequently debated feature of the rally. The mega-cap group accounts for a historically high share of the S&P 500's total market value, and narrow market breadth — the degree to which gains are shared across the full range of listed companies rather than a handful of leaders — has long been associated with choppier trading conditions, as index-level strength can mask weakness across the broader universe of listed companies.

The report notes that this reliance on artificial intelligence as the market's principal growth engine makes stocks susceptible to volatility should sentiment toward the technology shift. Much of the market's advance has been premised on continued heavy investment in AI infrastructure, and any reassessment of that spending could reverberate beyond the technology sector.

Near-term catalysts could test the market's resilience. Third-quarter earnings season, which traditionally begins in mid-October with results from major US banks, will provide a fresh reading on corporate health, while the upcoming US midterm elections in November 2026 could introduce additional uncertainties for investors.

For now, strong earnings and subdued volatility have kept the bull market intact as it nears the four-year mark. Whether market breadth broadens — and whether gains extend beyond AI-driven leadership — stands out as a key question for investors heading into earnings season and the elections.

Source: Economic Times Markets