S&P 500 Rebounds Nears Record Highs Driven by Western Digital and Seagate Gains

U.S. equity markets finished a surprisingly strong September and Q3 2025—the S&P 500 sat just shy of record highs while the Dow and Nasdaq logged their best September and Q3 showings in years—driven by upbeat earnings, rate-cut hopes and broad market optimism. Mega-cap AI and tech leaders such as Nvidia, Alphabet and Meta powered much of the move, but mid- and small-cap winners also lifted index breadth, with storage names and other outliers standing out. Western Digital surged (87.6% in Q3 and a ~168% YTD gain) and Warner Bros. Discovery jumped about 70% on restructuring hopes, while Seagate, Robinhood and others rank among the year’s top S&P performers, and Pfizer registered a notable intraday pop. Palantir and AppLovin are among the strongest mega-cap performers year-to-date as investors hunt durable leaders and long-term uptrends. Analysts caution that future total returns will depend chiefly on valuations at the time of purchase—advocating conservative Price/Peak Earnings frameworks and multi-year horizons—even as market risks (including potential government-shutdown volatility) and high-growth opportunities (e.g., certain AI/data-center plays such as Gorilla Technology) remain focal points for investors.